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"‘4 .f '44:} “4» 4’ ‘44- 44-44:- 44 4 344 . {3.— —— ..‘ m-u‘.“ on u .‘ u. ‘33» 31';— ~QH“ .. ..m .. . ..qw- .. . , M “a... . fi #3. . ““5”-“ . ‘ .. “ M -:§M-vr~z I ‘.'! ' '0‘" C ‘ mw‘v‘ ‘ ..‘ “'.': w.... 73:" "Ta": 3’. .m’w’ifl "a ‘z. “9-” , n...— 7" fl. ..'...— m.» *- ‘ l O 3 If 1 M ”l ‘5 mu IllllllllllllllllllllllHillll 3 1293 00590 2550 LIBRARY Michigan State University This is to certify that the thesis entitled Plant Response to Increased Moisture Due to Modification of a Sand Soil with Coal Fly Ash presented by l Bruce Allen Mac Kellar l has been accepted towards fulfillment of the requirements for M.S. degree in Crop and Soil Science Majox professor Date {/éZ/QO 0-7639 MS U is an Affirmative Action/Equal Opportunity Institution PLACE IN RETURN BOX to remove this checkout from your record. TO AVOID FINES return on or before one duo. '% DATE DUE DATE DUE DATE DUE W 2 we ma L___ if MSU Is An Affirmdiva ActloNEqunl Opponunl‘ty Institution PLANT RESPONSE TO INCREASED MOISTURE DUE TO MODIFICATION OF A SAND SOIL WITH COAL FLY ASH BY Bruce Allen Mac Kellar A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Crop and Soil Sciences 1990 (3“ r‘ \f‘. ABSTRACT PLANT RESPONSE TO INCREASED MOISTURE DUE TO MODIFICATION OF A SAND SOIL WITH COAL FLY ASH BY Bruce Allen Mac Kellar Field studies were conducted to examine the effectiveness of incorporating coal fly ash into coarse textured sand soils for improving soil moisture retention and plant productivity. Various rates of fly ash were incorporated to a depth of 70 cm with a Towner giant disk plow. Soil moisture was monitored by neutron hydroprobe and gravimetric sampling. Plant growth and dry matter accumulation of corn (Zea mays) was monitored. Corn moisture stress was measured with a leaf porometer, and corn root growth patterns were compared in both an ash modified and an unplowed soil. Grain yields for corn, wheat (Iriticgm aestiyum L.), and soybeans (Glycine max L;) and dry matter accumulation of corn silage and sorghum sudangrass (Sorghum_gglgarg Pers. x Sorghum vulgare sudanggse L.) were monitored. Soil moisture was increased substantially within the ash band compared to the surrounding sands. Corn plant growth measured by plant height and leaf area showed significant increases on ash modified soils compared to control treatments. Corn roots were capable of exploring the ash bands fully. Corn drought stress was reduced on the high ash treatments compared to the control treatments. Corn grain and silage yields were improved by ash incorporation. Wheat and sorghum sudangrass yields were also increased. Soybean yield showed no improvement on ash modified soils compared to control treatments. ACKNOWLEDGMENTS The author wishes to express sincere appreciation to Dr. A. Earl Erickson, who served as his major professor during the completion of the degree program, for the encouragement and insight which made this thesis possible. The author also wishes to thank Dr. L.W. Jacobs and Dr. H.C. Price for their participation as committee members. In addition, appreciation is expressed to farm managers D.A. Hyde and B. Graff for their willingness to provide time and equipment for the completion of this research. The author is indebted to technicians D. Campbell, N. Blakely, Xu Chuanguo, and graduate students P.E. Sierzega, B.E. Lentz, S. Bohm, and W.R. Berti for their assistance. The author also wishes to thank the many undergraduate students that have been involved in this research, especially M. Wilson, K. Speicher, and H. Swagart, for their willing participation in sometimes unwilling weather conditions. Finally, the author wishes to thank M.K. McCumber- Mac Kellar, for her patience, encouragement, and support during this program. iv TABLE OF CONTENTS LI ST OF TABLES O O O O O O O O O O O O O O O O O 0 LI ST OF FIGURES O O O O O O O O O O O O O O O O 0 INTRODUCTION 0 O O O O O O O O O O O O O O O O O 0 LITERATURE REVIEW Introduction to Coal Fly Ash . . . . . . . . Definition of Fly Ash Problem . . . . . . . . Alternative Uses of Coal Fly Ash . . . . . . . Physical Amendment for Improved Soil Moisture Drought Stress Timing and Corn Productivity . Potential Use in Michigan . . . . . . . . . . Soil Moisture . . . . . . . . . . . . . . . . Soil Amendments to Improve Moisture Retention. MATERIALS AND METHODS Experimental Sites and Treatment Design . . . Cropping of the Field Sites . . . . . . . . . Eaton Rapids . . . . . . . . . . . . . . . West Olive . . . . . . . . . . . . . . . . Plant Sampling and Measurement . . . . . . . . Methods of Soil Moisture Measurement . . . . . Soil Moisture Measurements . . . . . . . . . . Plant Moisture Stress Measurement . . . . . . Root Length Density Measurement . . . . . . . 10 12 15 23 23 24 27 29 31 32 33 RESULTS AND DISCUSSION Modified Soil Profile . . . . . . . . . . . . 35 Soil Physical Measurements . . . . . . . . . . 36 Climatological Information . . . . . . . . . . 42 Soil Moisture . . . . . . . . . . . . . . . . 50 Plant Growth and Development . . . . . . . . . 67 Corn Yield Component Measurements . . . . . . 86 Corn Grain Yields and Plant Populations . . . 90 Corn Silage Yields . . . . . . . . . . . . . . 100 Wheat Yield at West Olive . . . . . . . . . . 103 Soybean Yields at Eaton Rapids . . . . . . . . 106 Sorghum Sudangrass Yields at West Olive . . . 108 Bil-Mar Field Demonstration Area . . . . . . . 108 Plant Moisture Stress Measurements . . . . . . 112 Root Length Density Measurement Comparisons . 120 SUMMARY AND CONCLUSIONS . . . . . . . . . . . . . 125 LIST OF REFERENCES 0 O C O O O O O O O O O O O O 13 6 vi Table 10 11 LIST OF TABLES Corn vegetative growth as measured by plant height at West Olive and Eaton Rapids on July 29 and 30, 1987, respectively ........ Corn vegetative growth as measured by plant height at West Olive during the 1988 growing season ............................ Corn vegetative growth as measured by plant height at the Eaton Rapids Cuda site during the 1988 growing season ................... Corn vegetative growth as measured by plant dry matter content at West Olive during the 1988 growing season ....................... Corn vegetative growth as measured by plant dry matter content at the Eaton Rapids Cuda site during the 1988 growing season ........ Corn plant yield component lengths and dry weights from the West Olive research site during the 1988 growing season ............. Corn plant yield component lengths and dry weights from the Eaton Rapids research site during the 1988 growing season ........ Corn grain yields from the Campbell research site, West Olive, MI, from 1986 through 1988 0.0.0.0......'...OOOOOOOO00.00.0000...O Corn plant populations taken at the Campbell site, West Olive, MI, from 1986 through 1988 ..'...OOOOOOOOOOOOOOOOO00.000.000.00... Corn grain yields from the Miller Trust and Cuda research sites, located near Eaton Rapids, MI, from 1985 through 1988 ......... Corn plant populations from the Miller Trust and Cuda research sites, located near Eaton Rapids, MI, from 1985 through 1988 ......... Page 68 75 77 84 85 88 89 91 95 97 99 12 13 14 15 16 17 18 19 20 21 22 23 Corn silage yields harvested from the West Olive research site in fall, 1986 .......... Corn silage yields harvested from the West Olive research site in fall, 1988 .......... Corn silage yields harvested from the Cuda research site, located near Eaton Rapids, MI, during 1988 OOOOOOOOOOOOOOO0.0.0.0.0.... Wheat yields at the West Olive site harvested onJu1Y18, 1987 ..'..OOOOOOOOOOOOOOOO....0. Soybean yield at the Miller Trust site, Eaton Rapids, harvested on October 18, 1987 ...... Sorghum sudangrass yields at the West Olive site, harvested on August 24, 1988 ......... Corn vegetative growth at tasseling, (Vt), as measured by plant height and dry matter content at the Bil-Mar farms research site on July 27, 1988 ........................... Corn silage and grain yields from the Bil-Mar farms research research site in fall, 1988 0.00.00.00.00000000000000000000.0 Leaf parameter values measured for the lower leaf surface of corn at the West Olive site during the 1988 growing season ........ Leaf porometer values measured for the upper leaf surface of corn at the West Olive site during the 1988 growing season ........ Root length density measurements of an unplowed control and a 15 cm fresh ash treatment at the West Olive research site on September 5, 1988 ....................... Corn root length density values measured in the ash and sand fractions of a 15 cm fresh ash treatment at West Olive on September 5, 1988 viii 101 102 104 105 107 109 111 111 118 119 121 123 LIST or FIGURES Figure Page 1 Plot diagram, Miller Trust site, Eaton Rapids MI OOOOOOOOOOOOOOOOOOOOOOO0.0...O... 16 2 Plot diagram, Cuda site, Eaton Rapids MI .... 17 3 Plot diagram, Campbell site, West Olive MI .. 20 4 Observation pit exposing a 15 cm fresh ash treatment cut perpendicular to the direction of plowing at West Olive in early spring, 1987 ........................ 37 5 Water retention characteristic curves of Boyer loamy sand, Croswell sand, and coal fly aShOOOOOO..’...OOOOOOOOOO0......O. 38 6 Air porosities of Boyer loamy sand, Croswell sand, coal fly ash......................... 39 7 Pore size distribution of Boyer loamy sand, Croswell sand, and coal fly ash..... ....... 40 8 Cumulative precipitation through the growing season (a) and monthly rainfall departures (b) from 1986 through 1988 at the Campbell research site located near West Olive, MI.. 43 9 Daily precipitation received during the growing season in 1986 (a), 1987 (b), and 1988 at the Campbell research site located near West Olive, MI ....................... 44 10 Cumulative precipitation through the growing season (a) and monthly rainfall departures (b) during 1985 and 1986 at the Miller trust and Cuda research sites located near Eaton Rapids, MI...................... 46 11 Cumulative precipitation through the growing season (a) and monthly rainfall departures (b) during 1987 and 1988 at the Miller trust and Cuda research sites located near Eaton Rapids, MI...................... 47 ix 12 13 14 15 16 17 18 19 20 Daily precipitation received during the growing season in 1985 (a), and 1986 (b) at the Miller trust and Cuda research sites located near Eaton Rapids, MI ............. Daily precipitation received during the growing season in 1987 (a), and 1988 (b) at the Miller trust and Cuda research sites located near Eaton Rapids, MI ............. Moisture content of fly ash and sand between fly ash bands (15 cm fresh ash), topsoil O.M. bands and sand between bands (plowed control), and sand (unplowed control) at 37.5 cm (a) and 62.5 cm (b) depth at the Campbell research site, West Olive MI ..... Water content of fly ash modified Croswell sand at the 0-0.30 m (a) and 0.15-0.46 m (b) depths in plots planted to corn during 1986 at the Campbell research site, West Olive MI .................................. Water content of fly ash modified Croswell sand at the 0.30-0.61 m (a) and 0.46-0.76 m (b) depths in plots planted to corn during 1986 at the Campbell research site, West Olive MI .................................. Water content of fly ash modified Croswell sand at the 0.61-0.91 m depth in plots planted to corn during 1986 at the Campbell research site, West Olive MI ..... Water content of fly ash modified Croswell sand at the 0-0.30 m (a) and 0.15-0.46 m (b) depths in plots planted to corn during 1987 at the Campbell research site, West Olive MI .................................. Water content of fly ash modified Croswell sand at the 0.30-0.61 m (a) and 0.46-0.76 m (b) depths in plots planted to corn during 1987 at the Campbell research site, West Olive MI .................................. Water content of fly ash modified Croswell sand at the 0.61-0.91 m depth in plots planted to corn during 1987 at the Campbell research site, West Olive MI ..... 48 49 51 53 54 55 57 58 59 21 22 23 24 25 26 27 28 29 Water content of fly ash modified Croswell sand at the 0-0.30 m (a) and 0.15-0.46 m (b) depths in plots planted to corn during 1988 at the Campbell research site, West Olive MI .................................. Water content of fly ash modified Croswell sand at the 0.30-0.61 m (a) and 0.46-0.76 m (b) depths in plots planted to corn during 1988 at the Campbell research site, West Olive MI .................................. Water content of fly ash modified Croswell sand at the 0.61-0.91 m depth in plots planted to corn during 1988 at the Campbell research site, West Olive MI ..... Plant height measurements taken from the third uppermost (a) and second uppermost (b) corn leaves during the 1988 growing season at the Cuda research site, Eaton Rapids MI ................................. Plant height measurements taken from the uppermost corn leaf during the 1988 growing season at the Cuda research site, Eaton Rapids MI ........................... Plant height measurements taken from the third uppermost (a) and second uppermost (b) corn leaves during the 1988 growing season at the Campbell research site, West Olive MI .................................. Plant height measurements taken from the uppermost corn leaf during the 1988 growing season at the Campbell research site, West Olive MI ....................... Leaf area measurements taken on the uppermost (a), and second uppermost (b) corn leaves during the 1988 growing season at the Cuda research site, Eaton Rapids MI ............ Leaf area measurements taken on the third uppermost corn leaf during the 1988 growing season at the Cuda research site, Eaton Rapids MI ................................. xi 62 63 64 70 71 73 74 79 80 30 31 32 33 34 Leaf area measurements taken on the uppermost (a), and second uppermost (b) corn leaves during the 1988 growing season at the Campbell research site, West Olive MI ..... Leaf area measurements taken on the third uppermost corn leaf during the 1988 growing season at the Campbell research site, West Olive MI .................................. Transpiration rate measured on the lower surface of corn leaves on July 29, 1987 at the Campbell research site, West Olive MI ........................... ....... Transpiration rate measured on the lower surface of corn leaves on July 31, 1987 at the Campbell research site, West Olive MI .................................. Transpiration rate measured on the lower surface of corn leaves on August 8, 1987 at the Campbell research site, West Olive MI .................................. xii 81 82 114 115 116 INTRODUCTION Coal fly ash is a by-product of combusting coal by the electrical utility companies. Fly ash is the particulate material which is removed from the flue gas stream by emission control devices. This material accumulates rather quickly and soon becomes a solid waste management problem at the power plants. Sandy soils, prevalent in Michigan, tend to be dry due to a low water holding capacity. Since coal fly ash is composed mainly of silt sized particles, incorporating large quantities of this material into a soil could increase the water holding capacity of sandy soils. This would improve both the productivity of the modified sand and at the same time provide the utility company with a waste management alternative for large quantities of this by-product material. The goal of this research was to incorporate fly ash in a coarse textured sand soil, using a Towner giant disk plow, and to evaluate the effects of this practice on soil moisture and plant productivity. The primary objective was to quantify soil moisture retention improvement of the ash modified profile. Increased soil moisture would 2 provide a more favorable environment for plant growth and increased yields. Moisture content of both the consolidated and the individual (ash and sand) fractions of the modified profile were monitored. Evaluation of the benefits provided by increased soil moisture included the monitoring of plant growth and drought stress. Corn plant vegetative growth was monitored by plant height measurements at various times in the season. Plant moisture stress was monitored by measurement of transpiration, diffusive resistance, and leaf temperature deviation from ambient conditions, using a steady state leaf porometer. Root growth was evaluated to determine if corn roots were capable of exploring the fly ash bands in the modified profile. This was thought to be important for utilizing any of the increased moisture held within the ash materials. And finally, corn grain and silage yields, as well as grain yield of soybeans, wheat, and dry matter yield of sorghum sudangrass were recorded to determine the economic benefits of the practice. LITERATURE REVIEW t u t o t cal F sh Fly ash is the particulate product of combustion which is suspended by the flue gases and carried up the stack. These materials are either collected by emission control equipment or carried into the atmosphere. In April 1977, President Carter announced the National Energy Plan, which included a requirement for the implementation of the best available control technology in all coal fired power plants under construction. Emission control devices are primarily bag filtration systems or electrostatic precipitators. Additional residues from pollution control devices include products of flue gas desulfurization, which can be collected by spraying wet CaCO and CaO into 3 the flue gas stream to remove both particulates and SO 2 (Walker & Dowdy, 1980). Fly ash is amorphous ferro-alumino silicate material (Fisher et a1, 1976), in which between 70 and 90% of the particles may be glassy spheres (Hodgson and Holliday, 1966; Fisher et al, 1976). Particle size and chemical composition of this material may vary greatly depending upon the parent coal, fuel processing procedures and 4 combustion conditions, type of emission control devices used, and the collection, handling and storage conditions used (Adriano, et a1, 1980). An example particle size distribution of a western U.S. electrostatic precipitator fly ash is as follows: sand fractions ( > 0.05 mm), 32.5%; silt fractions (0.05-0.002 mm), 63.2%; and clay fractions (< 0.002 mm), 4.3% (Chang, et al, 1977). Unpublished work by Erickson and Jacobs” 1983, reported similar particle sizes in coal fly ashes produced by the Consumers Power Company in Michigan. Virtually every naturally occuring element has been identified in coal fly ash (Klein, et al, 1975). 'o h Fl Ash oblem Coal remains one of the United States most valuable energy reserves. In 1985, combustion of coal by the electric power generating utilities produced over 71 million tons of soild by-products each year, 80% of which were fly ashes (Golden, 1987). Although industrial uses may account for up to 50% of some European countries’ fly ash production (Brackett, 1967), the total utilization of fly ash in the United States in 1985 was at 27% of the amount produced (Golden, 1987). The methods most commonly used for coal fly ash management are either sluicing the ash from the plant to large settling ponds or land filling near the power generating station. Many of the currently operating 1 (A.E. Erickson and L.W. Jacobs, 1983, personal communication). 5 facilities have limited storage and disposal areas, and face shutdown if appropriate solid waste management options cannot be found. t t v sea 0 1 Fl As Many alternative uses for fly ash exist. Industrially, it has been used for structural fills and in cement mixtures. Many of the bottom ashes have been used in road bed construction, and have a fairly high utilization percentage in comparison to the fly ashes (Golden, 1987). The idea of utilizing fly ashes in an agricultural capacity as a soil amendment is not new. A great deal of research has been devoted to this goal, because it could create a large scale use for a widely underutilized by- product. Most of the published agricultural research has evaluated the addition of plant nutrients to soils by application of fly ash. While fly ashes generally do not contain N or P in sufficient quantities to satisfy crop requirements, they could be used to supplement Ca, 8, B, and Mo in deficient soils (Adriano, et al, 1980). Fly ash applications have been shown to supplement plant-available soil B (Ransome and Dowdy, 1987), Mo (Elseewi and Page, 1984), and S (Elseewi et al, 1978). In addition, fly ash has been utilized as a liming agent on acidic soils (Adriano et al, 1980; Page, et al, 1979). Because the texture of the fly ash predominantly lies 6 in the silt fraction (0.05 - 0.002 mm), incorporation of large quantities of this material may change the particle size distribution of amended coarse textured soils. This potential textural shift may affect inherent soil properties such as structure and water holding capacity. Improved soil moisture content may facilitate greater availability of plant extractable water. Fly ash additions to soils have been shown to increase the water holding capacity for most soil types (Salter, et a1, 1971; Chang, et al, 1977). Chang et al (1977) reported that while fly ash applications above 25% by volume consistently increased soil moisture retention, significant increases in plant available water were not found on either a Greenfield sandy loam or a Domino loam, homogeneously mixed with various rates of fly ash. Salter et al (1971) reported that large additions of fly ash (up to 753 t/ha) increased plant available water by as much as 93%. The soil used by Salter et a1 (1971) was more coarse in texture (54% coarse sand, 23% fine sand, 7% silt, and 14% clay) compared to the sandy loam used by Chang et al (1977) (9% coarse sand, 44% fine sand, 24% silt, and 10% clay). Both of these experiments were conducted with homogeneous mixtures of ash and soil. The disadvantage of homogeneously mixing of fly ashes with soils at high rates are potential reductions in infiltration and hydraulic conductivity, particularly on acidic soils (Chang et al, 7 1977), as well as potential problems of seedling mortality from salt or B toxicity (Ransome and Dowdy, 1987). Drought Stress Timing and Corn Productivity Many factors may play important roles in agricultural productivity. Soil fertility, structure, solar radiation, soil and air temperature, evaporative conditions, and soil moisture are all important components of crop production. Soil moisture has long been noted to be one of the most common limiting factors in plant growth and development. This may particularly hold true on crops such as maize, which are not overly drought tollerant (Jensen and Cavalieri, 1983). Robins and Domingo (1953) reported that the growth stage of the plant at the time of a water deficit had significant effects on the yield of maize. Depletion of soil moisture to permanent wilting point for 1 or 2 days at tasseling resulted in a 22% yield reduction, and extending periods to 6 to 8 days resulted in a 50% reduction in yield. Denmead and Shaw (1960) noted a 50% yield reduction with water stress prior to silking and a 21% decrease when a stress period was induced after the initiation of silking. Claassen and Shaw (1970b) showed that moisture stress imposed in the silking and early ear development stages caused the maximum reduction in kernel numbers. 8 More recent studies dealing with the maize yield component of kernel number suggest that stress during early grain development, rather than silking, results in a reduced number of kernels. Kiniry and Ritchie (1985) described an experiment in which stress was induced through the use of a shading interval. Horizontal panels were used to reduce the light which reached the plant by 79%. Kernel number reduction was closely associated with early kernel development stage (Kiniry and Ritchie, 1985). Grant et a1 (1989) reported that the interval during which grain set was most sensitive began 2 to 7 days after silking and ended between 16 and 22 days after silking. While the timing of a drought stress is detrimental during the early reproductive growth stages in maize, stresses occurring early in the vegetative growth stages and later in grain fill stages only marginally affect yields (Robins and Domingo, 1953; Denmead and Shaw, 1960; Claassen and Shaw, 1970a;). Prolonged or severe drought stress that results in leaf desiccation can markedly reduce plant height and vegetative yields, however, significant grain yield reductions by early season stress are only incurred if severe plant wilting takes place (Robins et a1, 1967). Yield reductions caused by drought stress during the time of silking are primarily a function of desiccation of either the pollen grains or the organs which transmit or receive the pollen. These yield 9 reductions are the result of pollination failure in which only a portion of the ear is filled with kernels (Robins, et al, 1967). Drought stress during flowering can also increase the interval between pollination and the onset of silking. In cases of severe drought stress, silking could be delayed until after pollen shed, resulting in kernel number reduction or barren ears (Herrero and Johnson, 1981). Grant et al (1989) demonstrated, however, that drought- induced reduction of kernel number is not absolutely dependent on the prevention of ovule fertilization. Hand pollinated plants, exposed to drought stress conditions during early kernel development, yielded lower kernel numbers than stress during and before pollination (Grant et al, 1989). Egtgntial Use in Mighigag Michigan is a state that is agriculturally diverse. A wide variety of perennial and annual crops are produced here because of special combinations of climatic factors and soil types. The agricultural productivity of these soils are generally limited by lack of water holding capacity (Erickson, 1972). Jensen and Cavalieri (1983) noted that soil type influences the extent of water deficits, and maize grown in regions with sandy soils may be particularly susceptible to drought stress during short periods without rain. 10 W Hillel (1982) uses the term ’soil wetness' to describe the percent moisture content by weight or by volume of a soil. Soil gravimetric or volumetric measurements report the quantity of water in a soil but are not a good measure of the amount of plant-available soil water. Plant- available moisture levels are best characterized by the matric potential of the soil (Hillel, 1982 ; Kramer, 1983). Matric Potential is the measurement of the free energy which characterizes the tenacity that the soil water is held by the soil matrix. Graphical representation of the relationship between the soil matric potential and the moisture content is known as the soil moisture characteristic curve. Factors affecting the matric potential of a particular soil include soil texture, structure, and organic matter content. Richards (1965) reported a procedure using a membrane apparatus for the lower matric potential determinations and porous ceramic plates at higher tension levels. Vomocil (1965) described a capillary model representing soil porosity. Initially saturated soil samples of known volume are exposed to increasing suction levels. The volume of water extracted at each suction level 'h' is equal to the volume of pores having an effective radius 11 greater than the 'r' in the capillary rise equation: r=2 1 905 6 g D h Where '1’ is the surface tension, '6’ is the contact angle (assumed to be zero), 'g' is the acceleration due to gravity, and ’D' is the density of the soil moisture (Vomocil, 1965). This equation indicates that as suction increases, progressively smaller pores will release their water content (Hillel, 1982). Since porosity is a function of both soil structure and soil texture, both of these components play important roles in soil moisture retention. Hillel (1982) reported that the amount of water retained at lower values of matric suction was primarily a function of soil structure. However, at increased levels of suction, water retention is increasingly affected by adsorbtion, and more directly related to soil texture. Moisture retention in sandy soils is characteristically low. Pore size in these soils tend to be large, due to larger particle sizes, and are generally more uniform than in other soil types. The moisture characteristic curves for sand show a rapid release of moisture at very low tension compared to clay or loam soils. Soil moisture availability for plant use is dependent upon the matric potential of the soil water. The relative range of plant-usable water has typically been described as 12 as being between the arbitrary moisture contents known as field capacity and permanent wilting point. Field capacity was defined by Veihmeyer and Hendrickson (1931) as the amount of water held in the soil after excess gravitational moisture had drained away and after the rate of downward movement of water had ended (Peters, 1965). Permanent wilting point was classically described by Briggs and Shantz (1911) as the soil moisture content at which plants growing in that soil first show wilting and cannot recover unless water is added (Kramer, 1983; Peters, 1965). Both field capacity and permanent wilting point tend to be variable, particularly the latter. Slatyer (1957) criticized the use of permanent wilting point as it is dependent upon the osmotic properties of the plants grown on these soils (Kramer, 1965). While there may not be a definitive point at which plants wilt, plant-available water is generally considered to exist between the ranges of 0.3 bar and 15 bars (Hillel, 1982 ; Kramer, 1983). s o i Moisture Reten '0 Sand soils are notoriously short of soil moisture. Unger et al (1981) stated that any method which increased the water retention ability of these soils would be beneficial, and this can be accomplished by adding materials which retain more water than sand alone. Several procedures have been used to increase the water 13 holding capacity of sandy soils. Where coarse textured soils are overlying a fine textured subsoil, deep tillage has been used to mix the two horizons together and increase the water holding capacity in the rooting zone. Unger et al (1981) reported that deep plowing of sandy soils in Washington (Miller and Aarstad, 1972), and in Oklahoma (Harper and Brensing, 1950) increased the clay content of the surface soils, and hence the water holding capacity. Additions of organic matter have been shown to increase the water retention of sandy soils (Jamison, 1953). While there may be an increase in soil moisture associated with organic matter additions, generally associated with better soil structure, it may not be practical as a sand soil moisture retention amendment. The ability of incorporated organic material to increase water holding capacity in coarse textured soils can be limited by the volume of material needed to significantly increase soil organic matter percentage. This may especially be a problem on droughty sand soils where the breakdown of organic matter can be rapid. Lucas and Vitosh (1978) estimated a humus decomposition rate of bare loamy sand to be at 4.5 percent annually, and reported levels as high as 7 percent decay for Metea loamy sand treated with 30 tons of manure per year under corn production. 14 Another approach to increasing the water holding capacity on droughty sand soils is to prevent the rapid downward movement of water through the use of an impermeable barrier. A system described by Erickson and Hansen (1968) reduces the infiltration through and out of the root zone, creating a perched water zone above the barrier. Asphalt films applied at a 60 cm depth showed the ability to maintain a zone of low tension plant- available moisture in a 20 cm band above the barrier while allowing sufficient infiltration and aeration in the surface 15-20 cm of soil. Plant-available moisture in the barriered profile was increased by 50 to 200% over the original sand solum (Erickson, 1972). Erickson reported significant increases in the yields of cucumbers and cabbage grown on barriered treatments without irrigation over the 'control' and the ’control with irrigation' on a field site composed of Ottawa fine sand in Allegan county MI (Unger et al, 1981). Saxena et al (1973) reported that the water stored in a profile in Florida was increased by at least 2.5 cm, and yields were increased from 0 to more than 150% depending upon the crop and season. MATERIALS AND METHODS ' e t S t s n e m nt es The first field experiment, the Miller Trust site (Figure 1), was established in the spring of 1985 on a Boyer loamy sand (Typic Hapludalf coarse-loamy, mixed, mesic) soil series located in T. 1 North, R. 3 West, Section 2, south of the Eaton Rapids middle school, Eaton County, MI. Soils of the Boyer Series are noted as being moderately suited to farming, with moderate permeability, and low available water holding capacity (Soil Survey of Eaton County, 1978). The experimental design at the Miller Trust site was a randomized complete block design (Steel and Torrie, 1960). The site was divided into 20 units, 12.2 m by 24.4 m in size, which established 4 replications of 5 treatments: unplowed and plowed controls, 5 centimeters (605 Mg/ha), 7.5 centimeters (908 Mg/ha), and 10 centimeters (1,210 Mg/ha) of fly ash incorporated into the soil. A second area, the Cuda site (Figure 2), located adjacent to the Miller Trust site, was established as an addition to this field experiment in 1986. The Cuda site contained the same soil series and was also designed as a 15 16 .Hz moflmmm coumm .ouflm undue Hedda: .aoumoflc uoam .H madman E V.¢N rm< Lauru an s_ .> >2 22 _ >_ ma £m< LUOLL EU m.n. n>~ 2 rm< rmmtu an m .___ m an >_ ~H~ -~ Lotscoo unsold .__ ~0LJC0U LDBO~QCD uH > > > r) mJ—LmEJUMLI—u -H -~ am Hm _ H >~ H m. .. are m an”. m use _ aom m~ >s 5‘ hegemocm Loocom slee.: me.mcm .m 17 .Hz mvwmcm :oumm .ouflm moso .amnmmwc node .N ousvfim £m< meLm EU m_ u> £m< ImmLL EU 8“ u>~ £m< immLm EU m nHaH Lorscoo nmsofid .HL HOLJCOU 1030~QEJ nH mHJrLMZEAwnZUILF. =“N.m_ 7 HH Ham >H HHH __H >~ HH __ HHH >H >~ HH v 00m m 00m N Qua _nEm “'S'UE fildedOJd Iooqos qEIH spzdvy '3 l8 randomized complete block experiment, with 4 replications of 5 treatments. The experimental area was divided into 20 units, 15.2 m by 30.5 m in size. The treatments consisted of: unplowed and plowed controls, 5 centimeters (605 Mg/ha), 10 centimeters (1,210 Mg/ha), and 15 centimeters (1820 Mg/ha) of fresh ash incorporated into the soil. Fly ashes used on these sites were supplied by the Lansing Board of Water and Light (BWL). The ash used on the Miller Trust site was a fresh ash that was transported from a landfill site by BWL personnel in covered semi- tractor trailer trucks. These trucks were specially fitted with a hydraulic ram to push the load of ash out the back of the trailer. Ash was spread on the appropriate plot area and then leveled out to the treatment depth with the front end blade of a D-7 Caterpillar tractor. The fly ash was incorporated with a Towner giant disk plow. This plow, which was manufactured in California, is typical of the type of equipment used for deep tillage of heavily compacted soils (Unger et al, 1981). The Towner plow was selected because of its potential depth of tillage. The four bottom plow, with disk blades 127 cm in diameter, was capable of incorporating ash to a depth of 65 to 75 cm. 19 Fly ash was applied to an individual replication and incorporated on the same day to prevent wind erosion of the exposed ash. The experimental site was plowed from south to north in one direction to avoid creating a huge dead furrow. The depth of plowing was 60 to 65 centimeters. This was partially determined by the power and traction capabilities of the D-7 caterpillar tractor used. The goal of this procedure was to find a way to incorporate the ash such that minimal amounts were left in the the upper 20 to 30 cm of the modified profile. The method of ash application was modified on the Cuda site. The fly ash used was from the BWL, this time the ash was brought directly from the holding bins that collected the electrostatic precipitator ash from the Erickson plant in Lansing, MI. The ash was applied using a spreader designed by Dr. C.M. Hansen, Professor Emeritus, Department of Agricultural Engineering, Michigan State University, and built by BWL personnel. This spreader hitched to the rear of the ash hauling trucks and dispensed an even 5 centimeter layer of ash over the surface of the soil. Applications to treatments requiring more than 5 centimeters of ash were accomplished by subsequent trips across the area. A third field site (Figure 3) was established in the spring of 1986 at an area located near West Olive, MI. This site, called the Campbell site, consisted of Croswell 20 .Hz o>flao umoz .ouflm Haonmamu .asummflu uon Lm< HumuLmrHEOm.) Eu SH uH> £w< IOMLL EU mH n> rm< rmmtu so 81 .>H 1m< rmmru an m "HHH HULLCDU HumsoHnH uHH HOLJCOU HUmBOHnHCD "H mYJPmeFTJnUmwffh emém. _ H> 3 > > >H HHH H HH > H HHH HHH HH HH HH >H H > >H H> HHH H> H> H v 001 m Qua N 00% I cum .m ousmwm m. 7H m nn nu m D 1 n1 nu U0 hr 21 & Au Gres sands (Entic Haplorthod sandy, mixed, mesic), located in T. 6 North, R. 16 West, Section 10, east of Hiawatha road, Ottawa County, MI. This soil was described as being not well suited for crops, having low fertility, as well as low available water holding capacity (Ottawa County Soil Survey, 1972). The experimental design was a split block (two crops), arranged in randomized complete blocks, supporting 4 replications of 6 treatments consisting of: unplowed and plowed control, 5 centimeter fresh ash, 10 centimeter fresh ash, 15 centimeter fresh ash, and 10 centimeter weathered ash. The experimental area was divided into 24 units, each 15.2 m by 30.5 m in size. The fly ashes used in this field experiment were transported from the Consumers Power Company Cobb generating facility in Muskegon, MI. The spreader used at the Cuda site was again used to apply the ash at the Campbell site. The fresh ash that was applied came from the electrostatic precipitators at the Cobb plant, while the weathered material was excavated from a fly ash sluicing pond located near the plant. The last field site was established in the spring of 1988 and is called the Bil-Mar Site. This site consists primarily of Rubicon sands (Entic Haplorthods, sandy, mixed, mesic) and is located in T. 6 North, R. 15 West, Section 7, Ottawa County, MI. The soil series is 22 described as having low natural fertility, rapid permeability, and very low water holding capacity. While the soil is not suitable for crop production without irrigation, it is used in a few places for specialty crops where irrigation is used (Ottawa County Soil Survey, 1972). This site was not designed for replicated experimentation, but rather as a large scale field demonstration area. Nearly 3.2 hectares were modified by an 1815 Mg ha'1 fly ash addition. Ash for this site was provided by Consumers Power Company, and was transported from the Cobb generating plant's ash sluicing ponds, near Muskegon, MI. The fly ash was transported from the ponds to the field site in 50 ton gravel trains. An ash receiving station was set up on the southern end of the field. The trucks dumped the ash in piles, which were then leveled out into loading strips with a road grader. The ash was picked up and applied to the field using a John Deere pan scraper. Application rates averaged 1815 Mg ha-l, a 15 to 20 cm layer was deposited on the soil surface. The fly ash was incorporated with the Towner giant disk plow used previously, pulled by a D-9 Caterpillar tractor from the Campbell generating complex. Ash incorporation disturbed the soil profile severely enough that it was too loose for conventional planting. A 23 secondary tillage operation, using a Brillion field cultivator, was performed on all sites except the Bil-Mar site, right after incorporation. This was done to consolidate the soil profile and to level the soil surface for better seed-soil contact at planting. ngpping of the Field Sites The cropping strategy for these field experiments was to: (1) field test the ability of the soil profile modifications to produce significant increases in crop yields and (2) evaluate any potential plant toxicities which might exist due to the application of fly ashes. Eaton Rapids The Miller Trust site, established in 1985, was planted to corn in the 1985 and 1986 growing seasons, and soybeans in 1987. The Cuda site, initiated in 1986, was planted to corn during the 1986, 1987, and 1988 growing seasons. The varieties used were, Voris hybrid (#V2331) in 1985 at the Miller Trust Site, and Pioneer hybrid (#3744) at both sites in 1986, and the Cuda site in 1987 and 1988. Corsoy 79 soybeans were planted on the Miller Trust site in 1987. Corn was planted with a 4-row Buffalo no-till planter, 75 cm row spacing at the rate of 65,700 plants per hectare. Liquid fertilizer, (10-34-0) was banded 5 cm below and 5 cm beside the row, at the rate of 123 kg he’l. Urea (46- 0-0) and potash (0-0-60) were custom blended and broadcast 1 at the rate of 270 kg ha- and 300 kg ha-l, respectively, 24 at the time of planting. Soybeans were planted with a Tye no-till drill, 20 cm row spacing, at the rate of 100 kg ha-l. Fertilizer (5-20-20) was applied through the drill attachment at the rate of 112 kg ha-l. An additional 67 1 kg ha- of potash (0-0-60) was broadcast prior to the time of planting. Weed control was maintained by a mixture of atrazine and alachlor (Lasso). The herbicides, mixed at the 4.72 L -1 ha rates, were used on the corn areas during the 1986 through 1988 growing seasons. Soybean weed control was established through the use of a 3-way mixture of metribuzen (Lexone) 4L 0.88 L ha.-1 1 , alachlor (Lasso) 4L , and glyphosphate (Roundup) 3.5 L ha"1 rate. 5.8 L ha- The insecticide Counter (terbufos (S-[[(1,1-dimethylethyl) thio] methyl] 0,0-diethyl phosphorodithioate)) 15 G, was applied at the time of planting to the corn to provide Corn Rootworm (pigbrgtigg lgggincornis) control. West Olive Crops raised on the Campbell site were corn and soybeans, 1986; corn and wheat, 1987; and corn and sorghum sudangrass, 1988. Corn and soybeans were planted on June 10, 1986. Soybeans were planted on adjacent sides of each block, so that the soybeans from the middle two replicates were planted and grown next to soybeans on the outer two replicates. Corsoy 79 soybeans at the rate of 32,100 plants per hectare, with the remainder of the area planted 25 to corn (Pioneer #3744) at the rate of 64,200 plants/hectare. Both the corn and soybeans were planted with a John Deere 7000 minimum tillage planter, 75 cm row spacing. The plots were fertilized with 135 kg ha.1 as urea (46-0-0), and 225 kg ha.1 as potash (0-0-60). Both 1 the soybeans and the corn had 112 kg ha- of (0-46-0) banded 5 cm beside and 5 cm below the row at the time of planting. Herbicides were applied prior to planting on the corn areas and were incorporated in the initial tillage operation. The herbicide used in 1986 was a mixture of atrazine 1.2 L ha-l; cyanazine 2.3 L ha-l, and EPTC R- 29148 dietholate 2.4 L ha-l. Soil acidity was reduced by the addition of 6.7 Mg ha-1 dolomitic lime. Wheat was planted on the areas previously planted to soybeans on October 6, 1986. Augusta white winter wheat was planted using a Tye no-till drill, with 17.5 cm row spacing at the rate of 150 kg ha-l. Fertilizer 1 applications of 56 kg ha- of N as ammonium nitrate (34-0- 0) and 100 kg ha.1 potash (0-0-60). A second fertilizer application was made in April of 1987 consisting of 45 kg ha-1 N as urea (46-0-0) using a Gandy fertilizer spreader. In the 1987 and 1988 cropping seasons, corn was replanted on the same areas as in 1986 using a Buffalo no- till 4-row planter, 75 cm row spacing, at the rate of 65,700 plants ha-l. The variety used was Pioneer hybrid 26 #3707. Fertilizer applications of 295 kg ha.1 of potash 1 (0-0-60) and 270 kg ha- of urea (46-0-0) were made in 1987 prior to planting, using a Gandy fertilizer spreader. Preplant fertilizer applications in 1988 were the same as 1987, however, a broadcast fertilizer spreader was used. Liquid (10-34-0) was applied as a starter fertilizer through the planter at the rate of 123 kg ha-l. In addition, nitrogen and potassium were applied in late May (1987) and early June (1988) as a surface side dress application. Fertilizer was applied by hand at the rate of 45 kg ha.1 N as urea, and 45 kg ha.1 potash. Lime was 1 custom applied at the rate of 6.7 Mg ha- in 1987 on the area previously planted to corn. Weed control on corn grown in 1987 was provided by application of a mixture of atrazine 4L 2.3 L ha-l, and 1 alachlor 3.5 L ha- , sprayed preemergence. A second application of atrazine was made in an effort to control 1 weeds, postemergence, at the rate of 3.5 L ha_ with crop oil concentrate. Herbicide application in 1988 on corn 1 ground consisted of a mixture of 3.5 L ha- of atrazine and 4.7 L ha-1 of alachlor at the time of planting. An application of 3.5 L ha"1 of glyphosphate was made to both the corn and the sorghum sudangrass areas. Sorghum sudangrass was planted on June 8, using a Tye no-till grain drill, 20.3 centimeter row spacing at the rate of 38 kg ha-1. Fertilization was made preplant 27 broadcast at the same rate and time as the corn areas previously described. S as em Plants were measured at various growth stages in 1987 and 1988. Corn plant height and leaf growth was monitored in 1988. Plant height was monitored weekly until tasseling (Vt) by measuring the maximum leaf extension of the uppermost three leaves of five plants per plot area. Leaf area was estimated by measuring the length and width of the top three leaves of a corn plant, on the same five plants per plot area. Methods described by McKee (1963) and Daughtry & Hollinger (1984) calculate the area of a corn leaf with the relationship: A = F * (L * W) where ’F' is an empirically derived slope of the function of leaf area and leaf Length (L) * Width (W). Reported values of 'F' range from 0.73 (McKee et al, 1964) to 0.785 (Daughtry et al, 1984). An ’F’ value of 0.75 was used to calculate the leaf area on the plants measured in this experiment. Plant dry matter sampling of the above ground portions of the plants, cut above the brace roots, were taken at various times over the growing season. Plant samples were collected, 5 plants per plot area and dried at 65° C for 4 to 5 days and weighed. Plant heights were also measured on 20 plants per plot area during the 1987 and 1988 growing seasons. 28 Ear corn was harvested by hand from 12.2 m of row per plot and the ears husked and weighed. In 1986, 12 ears/plot were subsampled, run through a grain sheller, and evaluated for gravimetic moisture content. Grain samples were collected for tissue analysis, and ear corn harvest weights were converted to bushels of #2 shelled corn at 15.5% moisture. In 1987 and 1988, the harvest procedure was the same, however, all of the ears harvested were run through a tractor powered sheller and then evaluated for moisture content. Plant populations were determined for the area harvested. Corn silage yields, taken in 1986 and 1988, were measured by removing the ears from 12.2 m of row, weighing them, and cutting the corn plant off just above the brace roots. The stalks were then weighed in the field, and 5 stalks/plot were subsampled, chopped using a small flail chopper, for silage analysis and moisture determination. Ears were collected, 10 plot-1, to determine the moisture content for dry matter yields. Wheat was harvested in July of 1987 using a Hege plot combine. A 9.14 m by 9.14 m area near the center of the plot was harvested. Grain was weighed, and a subsample was collected for tissue analysis and gravimetric moisture determination. Yields were corrected to 13.5% moisture. Soybeans were harvested in October of 1987 using a Hege plot combine. An area 170 meters square was harvested 29 near the center of each plot. Grain was weighed, and a subsample was collected for moisture determination as well as grain tissue analysis. Yields were determined and corrected to 13% moisture. Sorghum sudangrass was harvested in August of 1988 using a flail chopper (Carter) harvester. A 9.14 m by 9.14 m area was harvested near the center of each plot. All of the vegetative material was removed from the plot, leaving only a 5-7.5 cm portion of the stalk remaining as stubble. The biomass was weighed, a subsample was collected for gravimetric moisture determination and tissue analysis, and yields were reported as Mg of dry matter per hectare. e ds of stur e sur men Soil moisture measurement can be achieved through several types of analysis. The most common and widely used method to determine the moisture content of a soil is gravimetric analysis. Soil is collected, weighed, oven dried, and reweighed to determine moisture content on a per weight basis. However, soil moisture information is often more useful when it is related on a per volume basis. Volumetric soil moisture contents can be determined directly by collecting a sample of known volume and completing the analysis as above. Soil moistures can be determined gravimetrically, and then converted to 30 volumetric moisture through the relationship: vw = mph/9w) where 'Vw' is the volumetric moisture content, 'w’ is the gravimetric moisture content, 'Pb’ is the bulk density of the soil, and 'Pw' is the density of water (Hillel, 1982). In addition to direct measurements of soil water content, several indirect methods have been developed. These include electrical resistance measurements, such as gypsum or nylon moisture blocks, and the neutron scattering method. Measurement of soil moisture with a neutron hydroprobe was developed in the 1950's and has gained wide acceptance because it allowed for non- destructive and repeated sampling of the same location (Hillel, 1982). Soil moisture is measured with the neutron probe by the thermalization of emitted fast neutrons. Thermalization occurs when a fast neutron encounters a nuclei of the same order of mass, an inelastic collision takes place, and much of the energy of the neutron is lost. Collisions with higher mass nuclei are elastic, and hence, little energy is lost. The hydrogen nuclei in soil moisture are nearly the same mass as a neutron, and are very effective in slowing down fast neutrons. Slow neutrons are backscattered to the probe and detected by boron-triflouride neutron tubes. The pulses generated are transmitted to a counter and data logger (Partridge, 1967). 31 The neutron hydroprobe consists of two main parts. It has a probe which contains the source of neutrons, typically of radium-beryllium origin, and an electrical impulse counter, which records the number of pulses of electrical power generated by the reflection of slow neutrons through a collector sensor. 'stu easurements Soil moisture was monitored throughout the growing season at each site. Weekly rainfall amounts were collected on site with a standard rain gauge. Daily precipitation amounts were obtained from recording stations located at Eaton Rapids and Grand Haven, MI. A neutron hydroprobe (Campbell Pacific Nuclear Corporation; Pacheco CA; Model 503 Hydroprobe) was used to monitor the soil water content on all sites, during all growing seasons. Measurements were made at 15, 30, 45, 60, and 75 centimeter depths, measuring the volumetric moisture content from 0 to 30, 15 to 45, 30 to 60, 45 to 76, and 60 to 90 centimeters respectively. Soil moisture was also monitored gravimetrically at the West Olive site during 1988. A large pit, exposing several bands of fly ash or organic matter (from the topsoil in the plowed control), was opened in an unplowed control, plowed control, and a 15 centimeter fresh fly ash treatment. Material was carefully removed from the profile at 12.5, 37.5, 62.5 and 76 centimeter depths, and 32 placed into sealed aluminum weighing tins. Samples were collected from within and between the ash and organic matter bands at 37.5 and 62.5 centimeters deep. Gravimetric moisture content was determined by weighing the sample and then oven drying the soil at 1050 C for 48 hours and re-weighing. st ss Mea Transpiration is the process in which internal cell water is diffused through the stomata and evaporated into the atmosphere. Stomatal opening and closing is a function of the turgor pressure of the guard cells in the leaf. Essentially, the rate of transpiration is regulated by the supply of energy available to evaporate water, the difference in vapor concentration or pressure between the leaves and air (the driving force), and resistances in the water vapor pathway. Resistances are the leaf-air boundary layer, the cuticle, and the stomata (Kramer, 1983). Measuring the transpiration of a plant can be accomplished through the use of a leaf porometer. Porometers measure the rate of diffusion of water vapor from the leaf surface and readings are measured as diffusion resistance in s cm-l. Measured resistance is a function of cuticular resistance as well as stomatal resistance. If vapor flow through the cuticle is characteristically low, the measurement is a good 33 approximation of stomatal resistance (Kramer, 1983). Steady state diffusion porometry involves measuring the transpiration of a leaf at ambient conditions. Steady state diffusion porometers measure the flux of water transpired in the chamber, which is then balanced by the outflow of air, at the balanced humidity. Plant moisture stress was monitored at various dates during the 1987 and 1988 field seasons at the West Olive site. Transpiration, diffusive resistance, and leaf temperature deviation from ambient conditions were measured using a leaf porometer (Licor Corporation; Lincoln NE; Model LI-1600 Steady State Porometer) on corn leaves during times of drought stress. Photosynthetically active radiation (PAR) levels were monitored at the time of measurement. e ' e s e Root growth and exploration in the ash bands and the surrounding soil in a 15 centimeter fresh and an unplowed control treatment were measured during the 1988 growing season. A single pit was excavated in each plot sampled, and a perpendicular face was created in the profile 37.5 centimeters away from a row of corn plants. Samples were taken at depths from 0 to 7.5, 7.5 to 15, 22.5 to 30, 30 to 37.5, 37.5 to 45, 45 to 52.5, 52.5 to 60, 60 to 67.5, and 67.5 to 75 centimeters deep at spacings from 0 to 12.5, 12.5 to 25, and 25 to 37.5 centimeters on both sides 34 of the row. Flat sheet metal cutters, fashioned from 12 gauge steel, were used to separate a 7.5 cm deep by 12.5 cm wide by 76 cm long soil samples. Once the sample was isolated from the profile, the material was separated into ash, sand, or an ash-sand mixture components. Samples were separated by carefully removing some of the mixed material, and then by scraping the surface of the ash clean of sand and mixed soil, clipping the roots at the proper boundary. Each material was weighed, and a subsample was taken to determine the gravimetic moisture content. Samples were then stored in a cooler, 50 C, until they were washed using a hydropneumatic elutriator (Smucker, 1982). Roots were stored in a 25% solution of ethyl alcohol in a cooler until analysis could be completed. Root length was determined by Tennent's line intersect method using a 2.5 square centimeter grid (Tennent, 1975). This method is a modification of the method described by Newman (Newman, 1966). RESULTS AND DISCUSSION 'ed S ' f le Soil modified with fly ash by incorporation with a giant disk plow results in a series of bands extending 75 cm in depth below the surface of the soil. The ash bands, which run parallel with each other, are characterized by a curved vertical structure with a horizontal trailing edge at the bottom of the modified zone. These bands extend from 5 to 7.5 cm below the surface of the soil to the depth of incorporation. The configuration of the ash bands is such that there is not a continuous barrier to impede the downward flow of drainage water. However, the bottom of one band is below the top of the one adjacent to it. This allows a path for the drainage of excess water from an intense thunderstorm, while maintaining increased moisture for crop growth. Leaving large amounts of ash at or near the surface of the modified profile is undesirable, because sand-ash mixtures have been shown to reduce the saturated hydraulic conductivity rate and to promote runoff, rather than infiltration and recharge. 35 36 In addition to soil water relation considerations, ash on the surface of the soil can lead to increased dust and reduced emergence in seedlings due to increased concentrations of soluble salts or B. Evaluation of the soil profile at the West Olive site was undertaken in the spring of 1987. This allowed the disturbed soil to settle and to become fully recharged with moisture from the snow melt and spring rainfall. Observation pits showing an exposed modified profile are shown in Figure 4. A 15 cm fresh ash treatment, showing several exposed fly ash bands and adjacent sands, as well as associated increases in moisture, are illustrated here. The fly ash bands were saturated at this time, and maintained an area of increased soil moisture in the adjacent sand. 80' h s c eas em t Soil moisture characterization, air filled porosity, and pore size distribution curves of the Boyer loamy sand, Croswell sand, and fly ash are given in Figures 5 through 7, respectively. Soil moisture characteristic values (Figure 5) for the West Olive site show a field capacity (6 kPa matric 3 3 suction) value of 0.075 m m- soil water for Croswell sand. This indicates a very low water holding capacity and severe limitations for agricultural use. Boyer loamy sand from the Eaton Rapids sites retained 0.26 m3 111.3 soil 37 Figure 4. Observation pit exposing a 15 cm fresh ash treatment cut perpendicular to the direction of plowing at West Olive in early spring, 1987. (The fly ash is the dark bands which extend to 75 cm below the surface of the soil). 38 0.60 0.50- - 0.40— — 0.30- 6 0n3rn_3) 0.20— 010‘ H Fly Ash « o—o Croswell Sond G—B Boyer Loomy Sond I Tj'IITI fiTTIIIIII I I IYIIIVI 0.00 0.1 1.0 10.0 100.0 Motflc Sucfion (kPo) Figure 5. Water retention characteristic curves of Boyer loamy Sand, Croswell sand, and coal fly ash. 39 0.50 9—9 Boyer Loomy Sand 1 0—0 Croswell Sond V—v Fly Ash 0.40- - é?‘ _ .‘ I r. = ' 0.30- _ E N) -1 E u . V 0.20- H O 5 C1. " ' 010- a _ O-OO IT I I I 1 VIII 1 I U V Y TYTT 0.1 1.0 10.0 100.0 Motflc Sucfion (kPo) Figure 6. Air Porosities of Boyer Boyer loamy Sand, Croswell sand, and coal fly ash. 40 50 - H Fly Ash 45- 0—0 Croswell Sond ‘0 ‘ B—El Boyer Loomy Sand 3'.) 401 O 4 CL 35~ “‘5 J = ° 2% 30- 32 25- ' O ‘ ' a >> 20- *5 ‘ ~ = Q) 15‘ = 8 ‘ ‘ Q) 10- ' o. . 5 ‘ 5— c - O I IT I r l I T l I II TI 1 l l l l s a ‘ Pore Size Lorger Thon (um) Figure 7. Pore size distribution of Boyer loamy Sand, Croswell sand, and coal fly ash. 41 water at field capacity, indicating large differences in soil textures between the research locations. Fly ash moisture release characteristics reveal a much greater value, 0.47 m3 m-3 moisture content, at field capacity. At the 100 kPa matric suction level, volumetric soil water levels for Croswell sand, Boyer loamy sand, and fly ash were at 0.5, 0.16, and 0.35 m3 m-3, respectively. This shows good separation of the relative availability of the soil water for plant use between the soils and the fly ash additive. In an attempt to ascertain the lower limit of plant available moisture, samples were equilibrated at 1500 kPa matric suction (commonly accepted as the permanent wilting point). The moisture content of the fly ash sample was 0.029 m3 m-3, indicating that nearly all of the moisture retained by the fly ash incorporated into the soil was available to the plant. Air porosities for Croswell sand, Boyer loamy sand, and fly ash are shown in Figure 6. These relationships show that the majority of the pore space in the Croswell sand is filled with air at field capacity, while Boyer loamy sand and fly ash are considerably lower, (2.5 and 6.5 times, respectively). Pore size distribution of the three materials is given in Figure 7. Again, there is a large separation between the Croswell and Boyer soils. Most of the pores ranged between 20-80 um in the Croswell sand. The Boyer loamy 42 sand has a more even distribution, with a larger proportion of the pores 10 um or smaller than the Croswell. The majority of the pores in the fly ash are 10 um or smaller. ato ca ormat'on Rainfall patterns for the West Olive site from 1986 to 1988 are given in Figures 8 and 9. Rainfall amounts varied each year. 1986 received the most rainfall, and 1988 the least during the growing season. Cumulative rainfall totals for the May through September growing season peaked 550 mm in 1986, 440 mm during 1987, and reached only 260 mm in 1988. Precipitation exceeded the long term average (1940-1970) recorded for the 5 month growing season , 377 mm, during 1986 and 1987. Distribution patterns for rainfall varied over the period of the study. At the West Olive site, rainfall was either at or below normal during May and June, and well above normal in September for all three growing seasons. The 1986 season was characterized by above normal rainfall in July and August, and a wet September, when 102 mm of rain fell, accounting for 60% of the seasonal departure. By contrast, 1987 and 1988 were both very dry in May and June, and still below normal in July. The extent of the drought was more severe during 1988. Rainfall was near normal during August in 1987 and 1988, and above normal during September in 1987. Daily precipitation data for 43 A 700 E J — 1986 O: E 600. --- 1987 v 5004 _ g 400— - § 300- 7 It} 200- '— 0 - .. 8 100- _ CL ‘ .. O T 1 I 1 U I r I I I I l I I l I Y I I I I 5/01 5/21 6/11 7/02 7/23 8/13 9/03 9/24 200 g . A 3 [:1 1986 b 3 E ‘50? 1987 a E, 1003 m 1988 7 J : /’ 1 50-3 4 t of /§_5 2% ag 0 -50-3‘ F513 .5 -100‘ ‘ MAY JUN JUL AUG SEP Figure 8. Cumulative precipitation through the growing season (a) and monthly rainfall departures (b) from 1986 through 1988 at the Campbell research site located near West Olive, MI. 44 90 80: 1986 O 701 60': 501 40- 20: 10- O1 I" LA! T] I W 111111411111. 601 1987 b S RokfioH(nvn) 50: 1988 C : 20:: H I 1 1' 5/01 5721 6/11 7/02 7/23 8/13 9 03 9 24 Date Figure 9. Daily precipitation received during the growing season in 1986 (a), 1987 (b), and 1988 (c) at the Campbell research site located near West Olive, MI. 45 May to September from 1986 through 1988 is reported in Figure 9(a,b,c). The rainfall distribution information illustrates that the conditions for soil moisture and crop growth were somewhat similar in 1987 and 1988 but were more moist during the 1986 growing season. Rainfall patterns for the Eaton Rapids research sites from 1985 to 1988 are given in Figures 10 through 13. Yearly rainfall totals were variable, with 1986 receiving the greatest rainfall, and 1988 receiving the lowest during the growing season. Cumulative rainfall for the May through September growing season was 392 mm in 1985, 505 mm in 1986, 450 mm in 1987, and 390 mm in 1988, (Figure 10a and 11a). Precipitation amounts equaled the long term average (1940-1970) recorded for the 5 month growing season , 396 mm, in 1985 and 1988, and exceeded this level during 1986 and 1987, due principally to heavy rainfall in the month of September. At the Eaton Rapids site, the 1985 season was characterized by a dry May and June, a wet August, and a dry September (Figure 10b). During the next three years, rainfall was either at or below normal during May and June, and at or above normal in August and September for the 1986 through 1988 growing seasons (Figure 12b). The 1986 season was characterized by above normal rainfall in July, and an exceptionally wet September. Like West Olive, 1987 and 1988 were both very dry in May and June, 46 700. a 1 1:2: 1 500- 'l 400; , ----- 'd 3003 , ............ >’*“" 2003 . " —“’r/ 100$ """"’ Precipitation (mm) O _.______.'.,.—— T T I I I r47! F I I I r7 U I I it 1 I ‘47 r’* 5/01 5/21 6/11 7/02 7/23 8/13 9/03 9/24 200 nan are D 8551986 0100' 000 O lllllllllllllllllllllllllll Departure (mm) lllllllll lllllllllllllllllll ' I 0 01 O 0 Figure 10. Cumulative precipitation through the growing season (a) and monthly rainfall departures (b) during 1985 and 1986 at the Miller Trust and Cuda research sites located near Eaton Rapids, MI. 47 A 700 0 ~ — 1987 w E 600? 1988 1 xx 500‘ d .5 400- Jr'— jcj 300— ..... — 1% 2001 ’(2/ — Q) /’.'." .: i 1001 rrrrff/ ....... " O I I I 7 I I U I I I r T I I lfifT I I 5/01 5/21 6/11 7/02 7/23 8/13 9/03 9/24 200. A 3 r2221 1987 b 3 E 150‘; m 1988 E j; 100% 5 (D 2 2 ~ a at: 3 .. . ‘5 o: e m a e § —so~: g : :5:5: 3 "00 MAY Juu JUL AUG SEP Figure 11. Cumulative precipitation through the growing season (a) and monthly rainfall departures (h) during 1987 and 1988 at the Miller Trust and Cuda research sites located near Eaton Rapids, MI. 48 70 i 0 . 501 1985 _ A 50- _ E i i e a :6 'i 4 E 30‘ _ a? i - 20— 4 ‘ '1 104 I ‘l 4 o 1 ll , , L,L.ledrll ll, [1 , . , ,, , , 5/01 5/21 6/11 7/02 723 8/13 9/03 9/24 Date 60_ 1986 Rainfall (mm) 10: J 0: I- h'LJJI tIlI'L [L I I 5/01 5 21 6/11 7/02 7/23 8/13 9/03 9/24 Date Figure 12. Daily precipitation received during the growing season in 1985 (a) and 1986 (b) at the Miller Trust and Cuda research sites, located near Eaton Rapids, MI. 49 7O 60_ 1987 _ 50% _ 30- - Rakfia”(nvn) 20— - 10- A 0 J1, IJ RUI. 1 ,li, Ill [it I'll. LII] I q ‘ l I l 5/01 5/21 6/11 7/02 7/23 8/13 9/03 9 24 Date 70 60- 1988 .. 50d - 4a— — RahfiaH(nvn) . 10— ' L - 0. r I I .1 I . n .1! lJfl ‘ ' ' I "r T" I T ' I I ' T‘ 5/01 5/21 6/11 7/02 7/23 8/13 9/03 9/24 Date Figure 13. Daily precipitation received during the growing season in 1987 (a) and 1988 (b) at the Miller Trust and Cuda research sites, located near Eaton Rapids, MI. 50 with the most severe drought conditions occurring during the 1988 growing season. Precipitation was only slightly below normal in 1987 and somewhat above normal in 1988 during the month of July. Daily precipitation data for May to September from 1986 through 1988 is reported in Figure 13(a,b,c). The rainfall patterns at the Eaton Rapids sites suggest that soil moisture conditions for crop growth and production varied over the four year study and were frequently unlike the precipitation amounts received at the West Olive site. goil Moisture Moisture content was measured for the ash, sand, and incorporated A horizon components of the 15 cm fresh ash, unplowed control, and plowed control treatments at the 37.5 cm (Figure 14a) and 62.5 cm (Figure 14b) depths at West Olive during 1988. Soil moisture increases, within the the fly ash band, in comparison to moisture levels of the incorporated A horizon (O.M. band) of the plowed control, and sands of the unplowed control were substantial. The fly ash in the bands of the treated soils contained moisture levels which ranged from 400% more water in late July, to 150% more moisture by early September than the sand of the unplowed contol treatment. Although some increase in moisture content was shown during late July in the banded A horizon of the plowed control treatment compared to the sands sampled from the 51 0.50 H Ash Band 0 0—0 Between Ash A—A OM Band 0.40d o—o Between OM x—x Sand 6‘ I 0.30— E m E 0.20~ Q: 0.10~ 0.00 . 1 . I . I . I . l s 7/20 7/30 8/8 8/18 8/28 9/7 9/17 DATE 0.50 9—3 Ash Band b 0—0 Between Ash H OM Band 0'40“ 0—0 Between OM . x—x Sand «3“ | 0.30d E I“) E 0.20— Q 0.10- -I 0.00 r I . T T I . , . I . 7/20 7/30 8/8 8/18 8/28 9/7 9/17 DATE Figure 14. Moisture content of fly ash and sand between fly ash bands (15 cm fresh ash), topsoil O.M. bands and sand between bands (plowed control), and sand (unplowed control) at 37.5 cm (a) and 62.5 cm (b) depth at the Campbell research site, West Olive MI. 52 unplowed control, these increases were very small compared to those of the ash bands. Moisture content of soil between the ash bands and the incorporated A horizon of the plowed control treatment showed no increases compared to the unplowed control treatment. While moisture increases within the ash band are dramatic, the 15 cm ash application rate represents a 25% addition to the solum by volume. This moderates the amount of water available for plant use throughout the profile by a factor of 4. The decline of moisture in the ash bands over the course of 1988 can be attributed to plant water use during the extreme drought conditions throughout the summer. There was inadequate rainfall to recharge soil moisture until late in the growing season. In addition, significantly increased plant vegetative growth was recorded on the 15 cm fresh ash treatment. Since evapotranspiration would be increased with greater plant growth, much of the soil moisture contained within the ash band was utilized to support the significantly increased vegetative growth and yields on these treatments. Volumetric soil moisture content values of fly ash modified Croswell sand at various depths, as measured by a neutron hydroprobe, are reported in Figures 15-17 for the 1986 growing season. Although fly ash incorporation took place just before planting in June, the abundant rainfall 53 0.25 H UNPLOWED DEPTH o—o.3o m H PLOWED ‘ 0—0 5 CM FRESH ‘ x—x 10 CM FRESH 0'20? 0—0 15 CM FRESH ‘ I“? H IO CM WEATH/ ' l y / E - \ r') 0.15: \ j \E/ s V Q ., 0.10- O 0.05 ' I T I ‘r l’ T I I I T 6/14 6/28 7/12 7/26 8/9 8/23 9/6 0.30 ‘ H UNPLOWED DEPTH 0.15—0.46 m H PLOWED 0—0 5 CM FRESH 025: H 10 CM FRESH 1 o—o 15 CM FRESH A ‘ H 10 CM WEATH N) l 0.20— E i N) 1 - 3 . E, 0.15; i . \ Q : .g/;\ : “"!!!!==E§:p/ 0.10- ‘ ‘ b 0.05.,1f ,.,,,1, 6/14 6/28 7/12 7/26 8/9 8/23 9/6 DATE Figure 15. Water content of fly ash modified Croswell sand at the 0-0.30 m (a) and 0.15-0.46 m (b) depths in plots planted to corn during 1986 at the Campbell research site, West Olive MI. 6 0n3rn—3) 6 0n3rn_3) Figure 16. 54 UNPLOWED DEPTH O.30-0.61 m PLOWED 5 CM FRESH 10 cm mesa I LSD (0.05) 15 CM FRESH 10 CM WEATH IIIIII A 0 0.30 r . fi . , . I . I 14 6/28 7/12 7/26 8/9 8/23 9/6 1 0.25{ 0.203 0.151 0.1o—j l 0.05: 0.00 ‘ H UNPLOWED DEPTH 0.46-0.76 m H PLOWED H 5 CM FRESH ILSD (0.05) H 10 CM FRESH H 15 CM FRESH H 10 CM WEATHA TN TN T” 5/ 14 ' 672a ' 7/‘12 ' 7/25 ' 8% T 8223 . 9}?» DATE Water content of fly ash modified Croswell sand at the 0.30-0.61 m (a) and 0.46-0.76 m (b) depths in plots planted to corn during 1986 at the Campbell research site, West Olive MI. 55 030 ‘ o—o UNPLOWED DEPTH 0.61-O.91 m I—I PLOWED ~ 0—0 5 CM FRESH 0.25j x—x 10 CM FRESH o—o 15 CM FRESH §;\ x—R10(HAWDUH I 020— E 1 ft) \E, 0J5- <5 I 0.103 005 4+ 6/ T . T ' I ' I 7/26 8/9 8/23 9/6 DATE ' I ' a 14 6/28 7/12 Figure 17. Water content of fly ash modified Croswell sand at the 0.61-0.91 m depth in plots planted to corn during 1986. 56 received during 1986 at West Olive allowed the ash bands to become moist, and differences in soil moisture between treatments were found. While high variability in measurements exist due to access tube placement in proximity to the ash band at any measured depth, some statistically significant differences between treatments were found, particularly at the lower depths measured. The trend of increased soil moisture with increasing rates of ash application was apparent for all depths except the 0.0 to 0.30 m interval. The 15 cm ash treatment showed a statistically significant increase in soil moisture over either control treatment on July 15 at this depth (Figure 15a). Soil moisture content values showed good separation at the 0.46 to 0.76 m depth (Figure 16b) with all ash treatments consistently recording increased soil moisture values over either control treatment on all sampling dates except the first. The 15 cm fresh ash treatment was significantly higher in soil moisture content than either control treatment on June 21, July 3, July 22, July 29, and August 21 of 1986. Soil volumetric moisture contents for the 0.61 to 0.91 m depth, shown in Figure 17, showed no statistically significant differences between treatments. Volumetric soil moisture measurement of ash modified Croswell sand at various depths, as measured by a neutron hydroprobe during 1987, are reported in Figures 18-20. 57 0.25 I H UNPLOWED DEPTH 0—0.30 m - H PLOWED 6—0 5 CM FRESH ‘ x—x 10 CM FRESH 020': 0—0 15 CM FRESH A H 10 CM WEATH rfl') -I E . n 0.15: E, Q -4 0.10- ‘ a 0-05 Y r I I . I 6/14 6/28 7/12 8/23 9/6 0.25 H UNPLOWED DEPTH OAS—0.46 m H PLOWED 0—0 5 CM FRESH ‘ H 10 CM FRESH 0‘20: o—o 15 CM FRESH A H 10 CM WEATH rtl') .. E '1 P’) 0.15? E, . ° 1 0.10- b . 0-05 ' T ' T ' I I ' T . 6/14 6/28 7/12 7/26 8/9 8/23 9/6 DATE Figure 18. Water content of fly ash modified Croswell sand at the 0-0.30 m (a) and 0.15-0.46 m (b) depths in plots planted to corn during 1987 at the Campbell research site, West Olive MI. 58 0.25 H UNPLOWED DEPTH O.30—O.61 m I—I PLOWED 9—0 5 CM FRESH ‘ x—x 10 CM FRESH 0-20‘ H 15 CM FRESH I“? ‘ H 10 CM WEATH IE j I LSD 0.05 r") 0.15: E, I m i 0.104 1 O 0.051,I,V,T‘,,, 6/14 6/28 7/12 7/26 8/9 8/23 9/6 0.25 ‘ H UNPLOWED DEPTH 0.46—0.76 m J I—I PLOWED < o—e 5 CM FRESH I x—x 10 CM FRESH 020‘ 0—0 15 CM FRESH 1 §;\ ‘M—RIO—l “' I :1: Transpiration (Mg cm"2 5’1) 4s 1 l . . 1 . . , r . r . . I r 1 I . , ,4 T . 1120 1150 1220 1250 1320 1350 1420 1450 Time (hours) Figure 33. Transpiration rate measured on the lower surface of corn leaves on July 31, 1987 at the Campbell research site, West Olive MI. 116 A 10- H Unplowed Control ‘ .— 9; H Plowed Control ‘ 1m ‘ o—o 15 cm Fresh Ash 3 (\l 8‘ 3 I C1 E 7* ‘ 0 J on 6: — 3: 5~ — C - .9 4T 3 4.2 .1 .3 3— ~ % -I C 2‘ — 8 d T J- 4 t— 14 3E;;:;;;:—» TT'T===3E===Fr~st ‘ 0 ‘ T ' l ' I ' T . I . I I I I 1420 1440 1500 1520 1540 1600 1620 1640 1700 Time (hours) Figure 34. Transpiration rate measured on the lower surface of corn leaves on August 2, 1987 at the Campbell research site, West Olive MI. 117 Diffusive resistance values measured on both the upper and lower corn leaf surfaces were consistently lower on the 15 cm fresh ash treatment than on either of the control treatments. Diffusive resistance values for lower leaf surfaces showed between a 3 to 4 fold decrease on the 15 cm ash treatment compared to either control treatment. The upper leaf surface recorded a 2 to 3 fold reduction in diffusive resistance as compared to the plowed control, and a 5 to 10 fold advantage over the levels of the unplowed control treatments. Leaf temperatures on the lower surface of the leaf ranged from 0.08 to 0.27 0C cooler on the 15 cm fresh ash treatment compared to those of the plowed control treatment and 0.13 to 0.30 0C cooler than the unplowed control treatment leaf temperatures. Plant stress measurements reveal the same general pattern for the upper pattern corn leaf surface Transpiration rates ranged from 2 to 4 times greater on the 15 cm ash treatments compared to the plowed control treatments, and from 3 to 12 times higher than the unplowed control transpiration rates. Increased transpiration, reduced diffusive resistance, and lower leaf temperatures above ambient on the 15 cm fresh ash treatments all show that these plants are consistently under less drought stress than plants grown on the control treatments. Stomates of plants grown on .8 1. 1. .cofiuMAomm m>fiuo< adamoduocecamouosm u ate + nmauoone mo.Hmm.o no.4HHNm.mH ma.oHoo.H mos” can woummed me.Mee.e ~>.ane.o~ ma.omflo.e meme neeHman mo.+oo.o o~.>+~m.- no.o+vm.a ewes nee ecumema ooo.Hon.o an.mdflwh.>~ ew.oHHe.H some msflnmmfi ooo.Mom.o nm.mnMoo.em ma.owme.o once hmHomoa ooo.+on.o an.n+mo.ofl eh.o+~>.~ move mos Houucoo ousonncb noawvona eo.H~¢.o mm.HHoe.o v¢.oflvm.~ cone ens omfleene mo.Mom.o em.nwem.e mo.~M~o.n mama mo~fi~mo co.+me.o mm.~+ee.o ~o.o+es.~ enva nun mmuonmd Hoo.Mc>.e ~o.~Mas.m om.owww.n some “whommu mo.Hno.c Hv.~Hmo.o ee.dwmm.v once mefinswa no.+oo.o eo.n+n~.ua eH.H+oh.~ new“ we» Houucoo oo3oam omHHmeeH me.HmH.o mH.oH>m.H eo.~Hm~.~H cone can mnHHNAwfl mo.M¢m.o m~.oMmo.~ mm.ownm.n mama oAHHoNeH mo.+mm.o oH.o+eo.~ ~m.o+mm.m ewes new anemone e~.wnm.o av.oMo~.m ne.omno.me some meflcnoa mo.Hno.o an.oHoe.~ n~.HHoH.HH mace mahosea mo.+ne.o m¢.o+ow.~ ~¢.~+oa.m mood mos o .E0 mm. and sneak EU HlOmm NIE m: 00 HI m le NIEO 5 ucmwnad Ecuu oocmumqmwm «<9 wusumummfims wood o>am=uuda :Oauoufiamcmua mafia mama acmaucuua + m>fiuo you: on» an seen no wonuusm mama uw3oH 0:» How owusmmwfi mosae> uwvwfiouon weed .comamm ucfi3oum anon on» unseat made .ON OHQUB 119 :OeuMeomm w>euo¢ >een0euonuc>mouose u m.ee ~n.oumh.e nose we» oeHoene mo.Mom.e ee.owme.se em.owmn.e meme meeflmmm ee.+nv.o em.e+ee.m em.o+e~.n «Nee men meflmeme mo.How.o ee.mmno.me no.owme.~ some emeomme pe.Heo.o v.oewwm.mv os.owoe.e once mewnnee mo.Hme.o n.oe+om.ee on.e+m~.~ move mos eoeucou oozoem omeemeee no.8no.oi me.oumm.n eo.onov.w none «es wheflmnee me.Mom.o no.6mem.m mo.oMev.e meme oeehomne mo.+mn.o m~.o+om.n ee.o+ee.m «wee new enueeme mo.mn~.o mm.ewmm.v me.~m4n.o some neeonee me.Hse.o en.eH~a.e me.eHm>.m ance meweeme mo.+mm.e he.o+on.n ee.o+-.u move men a A20 mes awe games 00m E 5 EU m m EU 5 e. mu m 00 e- e. mi unmene< Eoeu wocwumemmm +memsuueo QOeumuechmeB uses mama ucwsuceea m>eeo yum: on» an :uoo uo woouesm Home amen: on» ecu nonsmowe moseo> uwuwfiouom Home .comwmm ace3oeo meme may oneesp muem .HN OADQB 120 the 15 cm fresh ash treatment are functioning normally. The more drought stressed plants measured on the control treatments were less capable of transpiring water to reduce the heat load of the plant. These measurements provide evidence that the increased moisture held in the ash modified soil could be utilized to reduce the level of plant drought stress. Boot Length Qensity Measurement Comparisons Total root length density (RLD) measurements of corn plants grown in 1988 on the 15 cm fresh ash and the unplowed control treatments are reported in Table 22. The RLD was extraordinarily enhanced by the ash amendment, particularly at the lower depths sampled. Root growth was increased by as much as 10 fold at depths from 45 to 60 cm. Root length density values were enhanced on the 15 cm fresh ash treatment sampled to depths below the zone of ash incorporation. Values were approximately equal in the upper 15 cm, but decreased rapidly at depths below 22.5 cm on the unplowed control treatment. Root growth increase, in response to fly ash incorporation, shows the corn plant's ability to explore the ash bands, utilizing the increased soil moisture for plant growth and development. One possible explanation for the magnitude of the increase in RLD on the 15 cm fresh ash treatment is the difference in growth and yield of the above ground portion of the plants. The total dry 121 Table22. Ooznrootlmguidensityneastmaentsofanmplmedcamlaniamcn freshashtreatmentattheWestOlivereseardisitemSeptanberS, 1988. UmerValue.... lsmfreshash IowerValue.... unplowed control Dept-h (cm) ---------- Distamefranplant (cm) .......... Unitseczucm"3 25-37.5‘W 12.5-25 W’ 0-12.5 W 0-12.5 E 12.5-25 E 25-37.5 E .165 .510 . .367 .335 .363 .056 0-7.5 .133 .449 .521 .338 .508 .936 .313 .714 .237 .256 .551 .902 7.5-15.0 .483 .097 .236 .287 .328 .441 .742 .433 .316 .503 .292 1.440 15.0-22.5 .082 .122 .040 .126 .061 .057 .952 .671 .626 .787 .366 1.481 22.5-30.0 .069 .063 .031 .092 .147 .039 .593 .656 .525 .611 .653 .492 30.0-37.5 .089 .053 .063 .080 .047 .041 .552 .884 1.760 .751 .898 .939 37.5-45.0 .051 .052 .042 .044 .024 .040 .430 .724 1.003 .454 .284 .739 45.0-52.5 .037 .032 .052 .031 .024 .022 .466 .831 1.050 1.161 .659 .761 52.5-60.0 .052 .011 .031 .034 .023 .021 .139 .069 .094 .048 .011 .018 60.0-67.5 .021 .031 .020 .017 .015 .009 122 matter production on the 15 cm fresh ash treatments, as measured by corn silage dry matter yields, represents a greater than 2.5 fold increase over that of the unplowed control treatment. Plant vegetative growth rates monitored through tasseling, (Vt), indicate impaired growth on the unplowed control treatments compared to those of the 15 cm fresh ash. Plant moisture stress measurement also indicated that transpiration rates were consistently higher, and that leaf temperature above ambient conditions, were consistently lower, for plants grown on the 15 cm fresh ash modified soil in compared to plants grown on the unplowed control treatment. Root growth measured by RLD for the individual ash and sand components of the 15 cm fresh ash treatment are given in Table 23. Samples reported in this table were taken from 22.5 cm to 60 cm deep, where accurate separations of the ash and sand components could be made. The RLD values were generally higher in the ash band samples compared to those of the sand between bands. Higher ash fraction RLD values occurred on 21 of the possible 29 comparisons (one 22.7 to 30.0 cm sample contained no ash, marked N/A). The average combined RLD for all depths and distances from the plant was 0.35 cm cm"3 in the ash fraction and 0.21 cm cm- 3 in the sand fraction, showing a preferential disposition for growth in the ash. While some ash samples showed large increases in RLD compared to the sand fraction at 123 Table23. Oornrootlenguidersityvaluesneasmedinumeashandsarflfractions ofalSanfreshashtreatmentatWestOlivemSeptemberS, 1988. UpperValue Ashfraction IowerValue Sandfraction Depth (cm) --------- Distance from.Plant (cm) ---------- Units = cm c:In-:3 25-37.5 W 12.5-25 W 0-12.5 W 0-12.5 E 12.5-25 E 25-37.5 E .164 .344 .246 .454 N/AT' 1.206 22.5-30.0 .473 .226 .216 .064 .131 .048 .177 .488 .239 .354 .260 .188 30.0-37.5 .234 .165 .104 .147 .168 .190 .179 .500 1.371 .194 .298 .390 37.5-45.0 .242 .149 .215 .146 .296 .154 .175 .419 .178 .204 .164 .329 45.0-52.5 .141 .206 .686 .139 . 120 . 181 .096 .525 .453 .200 .141 .204 52.5-60.0 .120 .134 .285 .533 .246 .246 N/A+=mseparableashbandwaspresentinthissanple. Note: Wofnootla‘gflubensity (MD)weretakenfrun0to67.5cn deep. RLDvaluesformelayerssanpledatdepthsbetweenOtozz.5 ard60to67.5cnvereaanittedbecausefl1eydidmtourtainseparable ashfractims. 124 the same layer and others only small increases, roots were able to fully penetrate and explore the ash bands in a modified profile. SUMMARY AND CONCLUSIONS The moisture release curves of the Croswell sand, Boyer loamy sand, and fly ash show an increase in soil moisture for the fly ash at the 100 kPa matric suction level by a factor of three over the Croswell sand and two over the Boyer loamy sands. Since the fly ash has a 1500 kPa 3 m-3, a large matric suction moisture content of 0.02 m portion of this moisture is plant available. If fly ash can be incorporated into the soil profile in a concentrated band, the moisture release characteristics of this band should more closely resemble pure fly ash rather than a mixture of ash and soil. Once the ash has been incorporated into the soil profile, it should act similarly to other soils which contain layer(s) of different textures. Textural differences in layered soils lead to modified water infiltration rates as compared to uniform soil profile. Miller and Gardener (1962), when looking at the effects of thin layers of different texture sandwiched within an otherwise uniform profile, reported that while matric suction and hydraulic head in any conducting soil must be continuous throughout the profile, abrupt discontinuities 125 126 in wetness and conductivity may occur at the interlayer boundaries. Typically, research involving soil moisture infiltration through two distinct texture layers deals with horizontal layer configurations. When coarse textured soils with greater saturated hydraulic conductivity overlie a less conductive, finer textured layer, the overall infiltration rate of the profile becomes that of the least conductive layer. If the infiltration rate through the coarse textured upper layer is large enough, a perched layer of free water may form above the boundary. However, when a finer textured upper layer overlies a coarse textured horizon, subsequent movement of soil moisture into the lower layer is dependent upon the existance of enough positive head to allow water to penetrate the larger pore sizes of the soil below. While the fly ash incorporation procedure does not produce a continuous horizontal layer in the soil, it does create a similar situation where two distinctly different textures are encountered in downward flow. A perched water table would not be expected to develop in ash modified soils due to drainage potential between ash bands. 127 Infiltration and recharge of soil moisture into the ash band is most likely to occur during times when the soil is very wet or saturated. In Michigan, these conditions generally occur after snow-melt and during heavy spring rains. As the soil drains and dries, especially on very coarse textured soils such as Croswell sand, the large difference in pore sizes between the fly ash and the sand will cause a disruption of water flow out of the ash band. This break in continuity allows the fly ash to maintain a reservoir of soil moisture which can be readily used by plants. The banded configuration of ash in the soil would be expected to be efficient in increasing available soil moisture. However, to receive maximum benefit, plant roots must be able to penetrate and explore the ash layer. Soluble salt concentrations, and potentially high levels of boron, were thought to be possible deterrents for root growth within the ash band. Root sampling has shown, however, that corn plant roots are able to grow within this material. Soil moisture measurements have shown increased moisture content with fly ash modification of the profile. Gravimetric measurement has shown that even during 1988, the driest year of the three year study, fly ash band materials contained vastly more water than either the organic topsoil band in the plowed control or the unplowed 128 control. The moisture content of the soil between the ash bands showed no increase as compared to the control treatments. Volumetric moisture determination using a neutron hydroprobe showed consistent results during the 1986 season, but found less differences between treatments during the drier years of 1987 and 1988. Typically, either the 0.15-0.46 m or the 0.30—0.61 m depth showed an increase in soil moisture for the high ash application rates as compared to the other treatments. One possible explanation for the less definite measurement as compared to the results from the gravimetric sampling is the lack of resolution with the neutron probe. Measurement is made of a spherical shaped region around the probe, integrating soil moisture over the entire area measured. Hillel (1982) suggests one of the key drawbacks to use of the neutron scattering method is a low degree of spatial resolution. Since the access tubes are placed in the soil at random, the depth at which an individual tube may encounter a fly ash band is unknown. Cassel and Nelson (1985) describes the spatial variability associated with tillage as a function of vertical and lateral changes in soil texture, structure, and organic matter which change soil physical properties in relation to bulk density and mechanical impedance measurement. The same problems with spatial variability would be expected to exist with the incorporation of ash 129 in bands throughout the soil profile. Corn vegetative growth was substantially increased at the higher levels of fly ash incorporation. The largest separation between treatments were recorded during the middle of the growing season. Corn leaf area measurement revealed beneficial increases on fly ash modified soils, particularly at the Eaton Rapids site, where measurements showed consistent increase in the area of all three leaves on the 15 cm fresh ash treatment. The West Olive site measurements recorded good increases in leaf area on the third uppermost leaf, but showed less separation for the two uppermost leaves on during the three earliest dates sampled. Corn grain and silage yields have shown consistent, as well as statistically significant, increases on high ash modified treatments over those of the controls. Corn yields were enhanced by ash application in all years following the first year of ash application, and only showed reduced yields in response to ash application during 1985, the first growing season after ash application at the Miller Trust site. This may have been caused by such factors as lack of rainfall to fully moisten the modified profile before the time of planting and ash remaining on the soil surface reducing germination and seedling growth. Substantial increases in corn grain and silage yield recorded at the West Olive location 130 during the extremely dry year of 1988 were particularly impressive. Although not statistically significant, the 1988 yield trends of corn grain at the Eaton Rapids site, which received adequate rainfall in the late July through September period showed good increases over the control treatments. Some enhancements in yields were recorded by the plowed control treatments over those of the unplowed control throughout the period of the three year study. This suggests that a beneficial tillage effect created by deep plowing Croswell sand and Boyer loamy sand exists, and apparently can persist for a good deal of time. One possible explanation could be that the loosening effect of the deep tillage is persisting longer than anticipated. Increases in crop yields could not be explained by increased moisture retention of the banded A horizon in the plowed control treatment. Another consistent trend involving corn grain yields, and essentially all yields recorded except those for corn silage at the West Olive site, is the enhancement of yields on the 10 cm weathered ash treatment over the levels of the 15 cm fresh ash. This trend occurred in spite of an increased soil moisture advantage on the 15 cm fresh ash treatments. A possible explanation for this may be that the fresh ashes contain higher soluble salt or 8 concentrations, which could reduce plant growth, than the 131 weathered material. Adriano et a1 (1980) reported that the weathering of fly ash in storage lagoons can stabilize pH as well as precipitate soluble minerals which can minimize impact of ash application to soils on plant growth. Ordinarily, the nutrient blamed for crop growth and yield reduction in fly ash amended soils is B. While most t coal fly ashes are high in 8 content, it would be expected 3 to be partially removed from the ash by decant waters during the sluicing process. Although a negative effect due to a high B concentration may somewhat reduce the efficiency of the plant to extract the increased soil moisture on the 15 cm fresh ash treatment, yields were only marginally, and never statistically, lower than the 10 cm weathered ash treatments. The ability of the corn roots to penetrate and explore the ash bands, on an equal or slightly preferential basis than the surrounding sand, indicates that a toxicity affecting plant growth is not a problem for corn. Irrigated corn yields at the Bil-Mar Farms research site show potential for increasing water use efficiency in corn production on ash modified soils. While this site was a large scale demonstration area and not a replicated experiment, a greater than 2 fold increase in average corn grain yield for the ash treated soils compared to the unmodified controls illustrate the possible benefits. 132 Wheat at West Olive (1987), soybeans at Eaton Rapids (1987),and sorghum sudangrass at West Olive (1988), were used to compare the effects of fly ash incorporation on crops other than corn. Wheat and sorghum sudangrass both showed statistically significant increases with ash application over control treatments. Soybeans, planted during a dry period in the spring of 1987, lacked an adequate stand for a good evaluation. However, soybean yields were not reduced by increasing levels of ash incorporation. Plant moisture stress in corn was evaluated primarily by transpiration rate measurements taken during periods of visible drought symptoms. Consistently higher transpiration values were found on the 15 cm fresh ash treatment than on either control treatment during 1988. Leaf porometer measurements revealed consistently lower diffusive resistance values on the the 15 cm fresh ash treatments than on either of the controls. The average leaf temperature deviation from ambient conditions was also lower on the high ash amendments compared to either control treatment. The increase in transpiration rate, along with the associated drop in diffusive resistance, provides evidence that the increased soil moisture on the 15 cm fresh ash treatments was utilized by the plants to combat the effects of drought. 133 This is particularly impressive when comparing the plant heights and dry matter weights between treatments during mid-July when transpiration was measured. Plant height of the 15 cm fresh ash treatments were 15 cm greater than the unplowed and 8 cm larger than the plowed control treatments. Dry matter content on the 15 cm fresh ash treatment was double that of the plowed control, and increased 4 fold over the content of the unplowed control treatment. Both the plant height and dry weight measurements were increased significantly over either control treatment. And, finally, the RLD information illustrated that corn roots were capable of penetrating and exploring the ash bands completely. The concentration of roots within the ash fraction was greater than those found in the sandy material between the bands. This measurement showed that the fly ash bands within the soil, which were expected to be higher in soluble salt and Boron content, did not create an environment restrictive to root growth. Since the band configuration provides improved soil moisture holding capacity, and is the natural result of incorporation with a giant disk plow, root exploration of the fly ash material is essential for maximum benefit. Fly ash incorporation into coarse textured soils to improve the water holding capacity had previously shown some success. Although the concept has been tried with 134 large percentage additions of fly ash to soils (Salter et al, 1971; Chang et al, 1977), these incorporations were designed to be a homogeneous mixture with the soil. Even with available water holding capacity increased by as much as 93% at high rates of ash incorporation (up to 753 t ha- 1), Salter reported little positive effect on the yields of the crops tested. Chang reported that while ash applications above 25% did increase soil moisture retention at 20 centibars, the availability for plant uptake of this increased soil moisture between 10 and 80 centibars was minimal. The increased availability of soil moisture for the system described in this paper was dependent upon the integrity of the ash band. This process has been successful in physically improving moisture retention and increasing plant productivity of ash modified coarse textured soils. CONCLU§10N§ The following conclusions can be drawn from this study: Coal fly ash can be incorporated into a sand soil with giant disk plow, creating a series of parallel bands in the soil profile. These bands are capable of holding increased moisture compared to the surrounding soil. Corn plant roots are capable of fully exploring the fly ash band within the soil. Corn drought stress, as measured by transpiration rate, diffusive resistance, and leaf temperature above ambient conditions was reduced on Croswell sand modified by the 15 cm ash incorporation rate. Corn plants were able to utilize this increased soil moisture, producing increased vegetative growth and higher yields. 135 LISI' OFREF'ERFNCES Adriano, D. C., A.L. Page, A.A. Elseewi, A.C. Chang, and I. Straughan. 1980. 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