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Filmed as Xerox University Microfilms 300 North Z e e b Road Ann Arbor, M ichigan 48106 I I 74-13,961 REED, Frank C. P., Ill, 1943THE EFFECTS OF CHRONIC AND SINGLE NUTRIENT INPUTS ON FIRST YEAR FALLOW VEGETATION IN MICHIGAN. Michigan State University, Ph.D., 1973 Ecology University Microfilms, A XEROX C o m p a n y ,A n n Arbor, Michigan THE EFFECTS OF CHRONIC AND SINGLE NUTRIENT INPUTS ON FIRST YEAR FALLOW VEGETATION IN MICHIGAN By Frank C. P. Reed III A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Botany and Plant Pathology 1973 ABSTRACT THE EFFECTS OF CHRONIC AND SINGLE NUTRIENT INPUTS ON FIRST YEAR FALLOW VEGETATION IN MICHIGAN By Frank C. P. Reed III The response of first year fallow field vegetation to fertilization with 10-20-0 (NPK) fertilizer under different schedules was studied on the Michigan State University campus in 1972. was used and treatments were as follows: A 4x4 Latin Square design checks; 450 kg*N*ha ^ applied once; 45 kg*N*ha ^ applied weekly ten times; and 90 kg*N*ha ^ applied biweekly five times. The response of the plant community was measured in terms of changes through the season in species composition, community diversity, net annual above ground primary production, below ground pro­ duction and nutrient accumulation by above gound plant material. Changes in soil nitrogen {Kjeldahl) and nitrate were monitored in all treatments through the growing season. Results showed that fertilization, using any of the schedules in this study, increased net annual above ground production about 50 percent. Underground production in all treatments was statistically similar in September. Nutrient accumulation by above ground plant material showed that fertilized vegetation reclaimed about 45 percent of the nitrogen applied. ments . Diversity showed no significant response to any of the treat­ The number of plant species present decreased significantly in Frank C. P. Reed XII fertilized plots. application. This effect was most pronounced in the single fertilizer Soil nitrogen showed no pattern of change across the season .V in any of the treatments. Soil nitrate nitrogen decreased in checks and increased in other treatments over the season. The implications of this are discussed in terms of the relationship of the number of species and production within a season. The results indicate that the number of species and production tend to be negatively correlated in these plant arrays over the season. The possible cause of this is discussed. The species of plants composing the experimental plant arrays are discussed in reference to their biochemical pathway of carbon fixation and their performance as accumulators of nitrogen under fertilization. Finally, general considerations for the operation of a waste water renovation area are discussed in reference to the soil-plant system and its behavior. ACKNOWLEDGEMENTS I gratefully acknowledge the time, support and patient guidance of my major professor, Dr. Stephen N. Stephenson. Additional sugges— tions on this research and manuscript were provided by Dr. William E. Cooper, Dr. Peter G. Murphy and Dr. James Tiedje, and for this X thank them. Others who contributed both their time and knowledge in various ways include Bodil Burke, Lynn Murry, Carol Heppe, Darlene Valasek and Valerie Dryer. This research was financially supported by National Science Foundation grant GI-20 and the Water Quality Management Project at Michigan State University. TABLE OF CONTENTS Page INTRODUCTION 1 METHODS AND MATERIALS 5 Experimental Site Site Preparation Design and Treatment Data Collection Soils Nutrient Analysis Analyses 5 5 5 8 10 10 11 RESULTS 15 DISCUSSION 40 The Effect of Chronic and Single Nutrient Inputs on a First Year Fallow Plant Array Production Responses Number of Species Nutrient Accumulation A Spray Irrigation Area for Renovation of Secondary Effluent 40 40 46 48 53 CONCLUSIONS 58 LITERATURE CITED 59 APPENDIX 63 iii LIST OF TABLES Prototype AOV for Latin Square design used in this study 14 Species present in experimental area: biochemical pathway -C^ or C^. 16 AOV analysis for Latin Square design of above ground biomass production from four replicates of each treatment at each time period 18 Analysis of Variance for a Latin Square design of Shannon-Weaver diversity index from four replicates of each treatment at each time period. 19 AOV analysis for the Latin Square design of the number of plant species present using four replicates of each treatment at each time period. 20 AOV analysis for Latin Square design using esti­ mated underground biomass from four replicates of each treatment at each time period. 21 Diversity 22 (X + SE) in each treatment over time. Data for the 1972 season at peak annual above ground standing crop. 24 Number of plant species present. 25 — 2 Above ground biomass (X +_ SE) in g*m . 28 2 Below ground biomass (X + SE) in g*m . 29 Nitrogen accumulation above ground in Kg. per hectare (X SE) . 41 Field data comparison of results of this study with other studies 42 Percent nitrate nitrogen present in vegetation in each treatment over time 52 — Summary of thebiomass contributed to above ground production by each species at each interval in time over the season. Regression equations for July for unde:: ground biomass. iv. LIST OF TABLES TABLE A18. A19. A20. A21. A22-31. A32-41. — Continued Page Regression equations for August for under ground biomass. ®-*- Regression equations for September for under ground biomass. 82 Regression equations for October for under ground biomass 83 Ecological analogs for prediction of under ground biomass 84 Nitrate nitrogen (X +. SE) in parts per million for soil increments of 10 cm. from 0-100 cm. depth. 85 Percent Kjeldahl nitrogen (X SE) in soil increments of 10 cm. from 0-100 cm. depth. v* 89 LIST OF FIGURES Page FIGURE 6 1. Field design. 2. Number of plant species present 3. Mean nitrate nitrogen (ppm.)for treatment one (check) at each 10 cm. soil depth for each time interval over the season. 31 Mean nitrate nitrogen (ppm.) for treatment two (single) at each 10 cm. soil depth for each time interval over the season. 33 Mean nitrate nitrogen (ppm.) for treatment three (weekly) at each 10 cm. soil depth for each time interval over the season. 35 Mean nitrate nitrogen (ppm.) for treatment four (biweekly) at each 10 cm. soil depth for each time interval over the season. 37 Kjeldahl nitrogen (X + 2SE). Open symbols indicate C 3 species. Closed symbols indicate species. 50 4. 5. 6. 7. (X 2SE). 26 INTRODUCTION The increasing human population, its trend toward centralization and geographic concentration, and increasing rates of material consump­ tion pose a major problem to society— that of waste disposal. The employ­ ment of natural and managed (crop) ecosystems in processing the bioactive elements of domestic waste has been suggested as an alternative to tradi­ tional dilution-transport waste disposal methods (Sopper, 1971). Indeed, many industrial and domestic operations are presently utilizing natural or crop ecosystems to process (dispose of) bioactive wastes (see Law, 1968; Sopper, 1971). It is becoming increasingly apparent that acceptable and effective means of waste processing by natural vegetation or crop arrays must incor­ porate the essential features of natural nutrient cycling. In addition, one must consider the impact nutrient rich wastes will have on the pro­ perties of natural vegetation. It is imperative that we determine both the long and short range effects of wastes on those properties of natural communities which make them attractive for waste processing. systems are viewed as more stable than simple systems Diverse (Loucks, 1970; MacArthur, 1972) due to greater spatial and temporal distribution of processes. In diverse communities, individual plant populations display active growth phases that are temporally spaced, giving the system an 1 2 active period greater than that in a monoculture. It is the control and utilization of these populations which is important in the operation of an effective spray irrigation program for the distribution of effluents. Ecologists have long debated the relationships that appear to exist between diversity, productivity, dominance and stability of natural eco­ systems exemplified in papers by (Connell and Orias, 1964; Leigh, 1965; Golley and Gentry, 1966; Monk, 1967; McNaughton, 1968; Margalef, 1968, 1969; Cooke et a l . , 1968; Singh and Misra, 1969; Whittaker, 1969; Loucks, 1970; Hurd et al., 1971; Daubenmire, 1972; Stephenson, 1973a), but to date no con­ census has been reached. in relation to succession. Most debators have viewed these community properties Recent studies (Golley and Gentry, 1966; Hurd et a l . , 1971; Hall et al., 1971; Stephenson, 1973a) have attempted to examine community organization as it is affected by nutrient augmentation. exception of the study of Hall et al. With the (1971) these studies have used low levels of nutrients in single applications. Other studies, most notably the studies at Hubbard Brook (Likens et al., 1967; Bormann et a l . , 1968; Likens et a l ., 1970), have examined nutrient cycling in whole communities by removing the vegetation to deter­ mine its role. Here, however, I am dealing with nutrient cycling in a community that has been fertilized. The use of crop systems has been suggested (Sopper, 1971) for use in effluent spray irrigation systems. However, crop systems have some limitations, one of which is the completely synchronous active growing period of the vegetation. Agronomists (Adriano et al., 1972a, 1972b) have described the nitrogen movement and balance in row crop systems with an interest in the uptake and leaching of nitrogen in reference to the amount applied in fertilizer. However, this type of system 3 requires high maintenance through the addition of herbicides and insecti­ cides to prevent damage to the crop. These systems are sometimes over fertilized; this results in the crop being less efficient in reclaiming applied nutrient. through the system. The unreclaimed balance is either retained by or passes Another characteristic of crop (monoculture) systems, pointed out by Root (1973), is that with the total biomass of an area concentrated into one type of vegetation they are more susceptible to high levels of herbivory. This leads to the conclusions that less diverse systems would also be open to more herbivory. Less diverse systems with the majority of biomass concentrated in one or two species would presumably be more open to attacks from disease organisms. In short, less diverse systems seem more unstable, in the sense of being susceptible to cata­ strophic disruption of community processes. To date I know of no studies which have attempted to evaluate the impact of fertilizer on the total plant-soil relationships of natural communities. This study is an initial attempt at comparing the effects of chronic and single application inputs on the organization and proces­ sing ability of a first year fallow community. Although water itself will play a major role in processing ability, it was unavailable and only fertilizer was used in this study to simulate domestic waste, using levels of nitrogen (Total N ranging to 30 ppm.; N03~N ranging to 5.0 ppm.; organic and ammonium N ranging to 25.0 ppm.) presently found in secondary efflu­ ent from the East Lansing waste treatment plant as a guideline to esta­ blish amounts of fertilizer applied. The concentration of nutrient applied to the system is approximately three times that which would be contributed in effluent applied at two inches per acre per week if applied over a period of ten weeks and equal to the amount that would be applied in an 4 application period of 30 weeks. However, concentrations of nutrients in these and other wastes may rise, at least those of nitrogen. Also, the application period for spray irrigation may have to be shortened to take advantage of plants' growing season. Due to a shortened application period the concentration of nitrogen in the waste may have to be raised by some preprocessing to a level equal to that applied in this study. In this study the fertilizer was applied over a period of ten weeks. The utility of this research is that it has both applied and basic aspects. Relative to the former aspect, this research identifies some plants that accumulate high percentages of nitrogen, describes the biomass accumulated in vegetation through the season, and describes nitrate beha­ vior in soil receiving fertilizer application under different schedules. In the basic sense this research examines the interaction of plants and soil in relation to the ecological phenomena of diversity and primary production. METHODS AND MATERIALS Experimental Site The study area is located on the South campus of Michigan State University (T3N, R1W, S6), in Ingham County Michigan (Dept, of Conser­ vation Maps, 1965). The experimental site is generally level and includes two soil types, Miami and Conover loam, both possessing low water perme­ ability and high phosphorous adsorption capacity (Schneider and Erickson, 1972). The site had been abandoned from corn for about six years prior to site preparation and was dominated by perennial herbs (Agropyron repens, Taraxacum officinale, Solidago spp.). Site Preparation On May 12, 1972, sixteen random samples of one-quarter square meter each were selected on the site and all material above ground was harvested, placed in plastic bags and transported to the laboratory. Both living material and litter were separated into monocot and dicot and treated as described in the section on above ground biomass. This was done to ascer­ tain the amount of biomass and nutrient to be plowed under. On May 16, 1972, the site was plowed and disced in preparation for experimentation. Design and Treatment The experimental design utilized four treatment categories arranged in a 4x4 Latin Square (Figure 1). Blocks were 10x10 meters, each separated 5 6 FIGURE 1. Field Design A - Control O Kg*N*ha ^*wk ^ B - 45 Kg*N*ha ^ (over 10 weeks - weekly) C - 90 Kg*N*ha 1 (biweekly over 10 weeks) D - 450 Kg*N*ha ^ (one application) Om— |---------------- 55 m -------------- 1— 10m— | c B 0 A A D B C « D C A B B A C D Figure 1. 8 from adjacent blocks by buffer strips of four meters. Treatments were randomly, allocated once per row and once per column as specified by the design. Treatments consisted of the following amounts of 10-20-0 (NPK) fertilizer: one (1)-check; two (2)- 450 kg»N*ha ^ applied once; three (3)- 45 kg*N*ha 1 applied weekly for ten weeks; four (4)- 90 kg*N*ha 1 applied biweekly five times. Fertilizer was of the pebble type with nitrogen in the form of NH^NO^ and phosphorus as a mixture of soluble phosphates. Fertilizer applications were made by hand beginning on June 1, and continuing until August 3, 1972. Uniformity of fertilizer application was attempted by distributing the fertilizer as one handful of fertilizer per pace. This pacing was done five times in a north-south and five times in an east-west direction in each block. To check this ten containers with a diameter of 12 cm. each were randomly placed in a plot receiving 4.5 kg. of fertilizer. The mean amount of fertilizer per pot was 3.35 grams, the largest being 4.5 grams and the smallest 1.5 grams. This compares to a calculated amount of 4.0 grams that should have been present in each container. Data Collection Above Ground Biomass Above ground plant biomass was sampled monthly commencing in July and ending in October. Four randomly selected one-quarter square meter samples were harvested in each block at each sampling date. No subse­ quent samples were taken on previously sampled sites nor were any sites used that bordered on previously sampled sites. Materials were clipped at ground level, placed in labelled plastic bags for transport to the laboratory and stored at near 0°C until processing. 9 Each sample was weighed, separated by species, placed in a forced air drying oven at 100°C for a period not less than twenty-four hours, re­ weighed and the dry weight recorded by species. Nomenclature follows Gleason (1968). Below Ground Biomass A minimum of eight randomly selected individual plants of the five most common annual species (Amaranthus retroflexus, Chenopodium album, Ambrosia artemisijfclia, Polygonum pensylvanicum, Setaria glauca) were harvested in July, August and September. Sonchus asper, a perennial, was harvested as rhizome and all attached above ground parts in July and August. Roots and rhizomes of Agropyron repens were obtained in July, August, September and October from soil blocks ten by ten centimeters to a depth of twenty centimeters. All material was placed in labelled plastic bags and transported to the laboratory. The below ground material was cleared of soil particles using the method of Pavlychenko separated from the above ground material. (1937) and The cleared material was oven dried at 100°C for twenty-four hours and the dry weight recorded. Data concerning Solidago spp. was provided by S. N. Stephenson (unpublished data)„ Linear regression equations were developed to describe the ratio of above to below ground biomass. Since no difference was noted when annual plants were treated separately by treatment or combined from all treatments, the latter was used in this study. Since Agropyron did show a difference when treated separately by treatment and Sonchus did not, Agropyron was treated separately by treatment and Sonchus was combined when linear regression equations were developed. 10 Soils Soil samples were taken monthly in each block from June to October. Cores were removed to a depth of 1 meter in each block from quadrats pre­ viously used for vegetation samples. tions of ten centimeters each. Each core was divided into ten sec­ In June and July two samples per block were composited while in August, September and October single samples were taken due to difficulty of sampling. Each ten centimeter core segment was placed in a plastic bag, transported to the laboratory and weighed to de­ termine the wet weight. Each sample was then oven dried at 72°C for a minimum of forty-eight hours, removed and dry weight recorded. This material was then stored in labelled, sealed containers. Nutrient Analysis Plant All dried plant material harvested as above ground biomass was treated as follows. was combined. All dry plant material of each species in each block if the weight exceeded ten grams dry weight the material was completely ground in a Wiley Mill to pass a 50 mesh screen. Sub­ samples of ground material of each species in each block were further ground to pass a 20 mesh screen. This material was analyzed for total nitrogen using the Kjeldahl method.* Soil All dried soil samples were milled and analyzed for total nitrogen using the Kjeldahl method. Nitrate nitrogen was evaluated by mixing to­ gether 20 grams of soil with 50 ml. of CaSO^ solution {20 grams CaSO^^F^O). *Analysis was conducted in the laboratory of Dr. A. L. Kenworthy of the Horticulture Department at Michigan State University. 11 This material was shaken for thirty minutes and nitrate concentration determined using an Orion Model 801 ion meter. Analyses Diversity Diversity was calculated using the Shannon-Weaver formulation (Pielou, 1969) H ‘com m = -£p.i log 2 p.i where £ is the proportion of the i th species. Diversity within each block (community) was calculated using the summed above ground biomass from the four samples in each block. was calculated with a mean Diversity within treatments id standard error of the four replicates in each treatment. Evenness The evenness component of diveristy was calculated using the formu­ lation (Pielou, 1969) _ com H* com H' max where H ’ is the maximum diversity that can be attained by the number max of species present. As before, J' com within blocks was calculated from summed above ground biomass data of the four samples within a block. Evenness within treatments (J' com ) was calculated with a mean and stan- dard error of the four replicates. Nutrient Accumulation Within a block the estimated above ground biomass per square meter of each species was multiplied by the nitrogen content of that species and summed for all species in that block. Blocks within treatments were 12 combined and a mean and standard error of nutrient accumulation determined on a treatment basis. This was converted to a kilogram per hectare basis. Production Above and below ground production on each sampling date was determined for each treatment by summing the dry weight of each species in each block and combining blocks within a treatment to derive a mean and standard error for the treatment. For the below ground production, plants that appeared structurally similar to those harvested for determination were treated similarly, that is, the same regression equation was applied to them as to the sample species (Table A21). All species not included in this table with the exception of Solidago spp. contributed only minute quantities of below ground material. Peak community production was determined by com­ bining the peak above ground production of each species in a block and combining blocks to derive an estimate of peak community production in each treatment. Soil Analysis Both total nitrogen (as a percent per gram of soil) and nitrate nitro­ gen (ppm.) present in the soil in each ten centimeter increment was deter­ mined at each time interval for each treatment using data from the four replicate blocks in each treatment. Statistical Comparisons All data in tables that represent a mean of the four replicates in each treatment were tested for significant differences using Tukey's wprocedure, henceforth referred to as LSR (Sokal and Rohlf, 1969), where MS within and in this study n = 4, k = 4, and v = 6. The mean square within {error mean square) was derived using Analysis of Variance for the Latin Square Design. A prototype of the Latin Square analysis is given in Table 1. 14 Table 1. Prototype AOV for Latin Square design used in this study. df MS F_ Rows 3 x 21 Columns 3 y 51 Treatments 3 z a Error 6 a Source Total 15 a a RESULTS The major species contributing the bulk of the biomass in all treat­ ments were: Agropyron repens, Amaranthus retroflexus, Setaria s p p . , Chenopodium a l bum, and Polygonum pensylvanicum. Annuals dominated in July and early August in the check communities, but by the end of the season Agropyron, a perennial, dominated. In the treatment blocks annuals dominated the system throughout the season probably due to their rapid response to increased nutrient. Species recorded in the experimental area are indicated in Table 2, along with their biochemical pathway of carbon fixation which will be discussed later in reference to this study. Analysis of Variance for the Latin Square design was performed to test for treatment effect on above ground biomass, Shannon-Weaver diversity, evenness, number of species and estimated below ground biomass. differences (p Significant 0.05) were noted in above ground biomass due to treatment at all sampling dates (Table 3). Shannon—Weaver diversity showed an over­ all effect of treatment only in August (Table 4). Number of species showed a treatment effect in August, September and October showed no treatment effect at any sampling date. (Table 5). Evenness Estimated below ground biomass showed a treatment effect in July and August but not in September or October (Table 6). Diversity, calculated from biomass data (Tables Al-16) at each sample date for each treatment is presented in Table 7. Using the LSR test, no significant differences in Shannon-Weaver diversity were noted 16 Species present in experimental area: biochemical pathway - C 3 or C . 3 c„ 4 XX X X X X X X X X X X X X X X X Acalypha s p p . Agropyron repens Amaranthus alba Amaranthus retroflexus Ambrosia artemisiifolia Aster spp. Barbarea vulgaris Berteroa incarna Capsella bursa-pastoris Chenopodium album Cirsium vulgare Cyperus esculentus Caucus carrota Digitaria sanquinalis Echinochloa crusgalli Erigeron annuus Euphorbia maculata Glyceria spp. Hieracium spp. Juncus spp. Lepidium campestre Lychnis alba Malva spp. Medicago sativa Medicago lupiiina Melilotus officinalis Moss Osalis stricta Panicum capillare Panicum dichotomiflorum Panicum spp. Phalaris arundinacea Phleum pratense Physalis spp. Plantago lanceolata Plantaqo rugelli Poa compressa Polygonum aviculare Polygonum convolvulus Polygonum pensylvanicum Polygonum persicaria Portulaca oleracea Rumex crispus Setaria glauca Setaria viridis c„ X X X X X X X X X X X XXX Species X X X X X X X X X X X XX Table 2. 17 Table 2. Species present in experimental area; biochemical pathway - C 3 or Species Solanum nigrum Solidago canadensis Solidaqo graminifolia Sonchus asper Stellaria media Taraxacum officinale Thlaspi arvense Trifolium pratense Trifolium repens Urtica spp. Verbascum blattaria Unknown X X X X X X X X X X X 18 Table 3. Source AOV analysis for Latin Square design of above ground biomass production from four replicates of each treatment at each time period. F t is the F ratio for treatment. df SS, _ July SS August SS September SS October Row 3 36057.1 229339.1 246923.9 162813.1 Column 3 16315.2 12911.3 89788.9 28447.1 Treatment 3 53046.2 168328.5 522944.2 218474.7 Error 6 20384.3 36120.0 43623.6 41171.1 F .05(3,6) 4.76 Fm — 5.20 T F T = 9.32 F T = 23.98 F T = 10.6: 19 Table 4. Source Analysis of Variance for a Latin Square design of Shannon-Weaver diversity index from four replicates of each treatment at each time period. F t is the F ratio for treatment. SS df _ July SS August ss„ ^ . September SS October 2.265 0.161 0.697 0.213 Column 3 0.933 1.133 1.154 1.128 Treatment 3 0.645 1.072 0.783 0.884 Error 6 0.520 0.429 1.909 1. 214 F .05(3,6) 4.76 F T = 2.48 F T = 5.03 II O « 00 M 3 *4 Row T ~ 1.46 20 Table 5. AOV analysis for the Latin Square design of the number of plant species present using four repli­ cates of each treatment at each time period. FT is the F ratio for treatment. September SS^ October 10.25 3.25 60.19 32.69 43.25 72.25 38.19 3 44.69 131.25 158.75 311.19 6 42.38 df S S _ July Row 3 13 .19 Column 3 Treatment Error Source .05(3,6) = 4.76 = 2.11 SS August SS 53.5 5.0 F T = 52.5 F T = 5.93 60.88 F_ = 10.22 T 21 Table 6, Source AOV analysis for Latin Square design using estimated underground biomass from four replicates of each treatment at each time period. F^ is the F ratio for treatment. SS df , July SSAuqust SS September SSOctober Row 3 20907.78 9111.14 12951.30 6476.97 Column 3 6339.02 7190.58 5483.09 26647.69 Treatment 3 79580.28 62433.55 1099.90 40067.53 Error 6 3236.92 14036.78 10085.59 20549.41 F .05(3,6) 4.76 F T = 49.17 F T =8.90 F T = 0.22 F T = 3.90 22 Table 7. Treatment Diversity (X + SE) in each treatment over time. Values were derived from four replicates in each treatment. July August September October Check 2.78 + 0.37 2.70 ± 0.21 2.58 + 0.22 2.32 + 0.18 Single 2.42 + 0.26 2.07 + 0.14 1.99 +_ 0.23 1.77 + 0.24 Weekly 2.22 + 0.24 2.11 + 0.26 1.11 +_ 0.28 2.31 + 0.30 Biweekly 2.46 + 0.22 2.14 + 0.09 2.14 + 0.37 2.30 + 0.19 LSR = 0.71 .05 LSR = 0.6 .05 LSR = 1.38 .05 LSR = 1.09 .05 1- Values sharing superscripts are not significantly different at the 0.05 level using the LSR test. Comparisons are only made within a month. 23 between treatments at any sampling date or at peak standing crop (Table 8). The number of species recorded at each sampling date showed checks to be significantly higher (p <_ 0.05} than all other treatments in August and October. In September only the single application treatment was signifi­ cantly different (Table 9, Figure 2). checks had significantly more (p At peak community production the 0.05) species than all other treatments while treatment two had significantly fewer (p three and four (Table 9). 0.05) than treatments The comparison of above ground biomass showed checks had significantly less (p 0.05) biomass than all treatments in August, September and October (Table 10). It should also be noted that single applications tended to have higher biomass accumulations until September suggesting that the initial response period of the vegetation has much to do with the final outcome on the site. Predictive linear regression equations (Tables A17-20) were used to estimate below ground biomass in each treatment at each time period. Com­ parison of these estimates using the LSR test show checks to be signifi­ cantly less (p _<_ 0.05) than weekly and biweekly application treatments in July and August. less (p In July single application treatments had significantly 0.05) estimated under ground biomass than weekly or biweekly application treatments and significantly more (p 0.05) than checks. In September and October, no significant differences were evident between the estimated underground biomass in any of the treatments (Table 11). The October value in the biweekly treatment may be due to increased activity of Agropyron during September in this treatment. These data (Table 11) show the behavior of underground plant biomass is not similar to the be­ havior of above ground plant biomass (Table 10). Here, the estimated mean underground plant biomass in all treatments became more similar (converged) 24 Table 8. Treatment Data for 1972 season at peak annual above ground standing crop. Values are derived from the four replicates of each treatment. Diversity (H')1 Evenness (J) Biomass2 a 820.8 + 146.4 N3 al 0 8 .4 + 14.5 2.89 ± °*13 0. 58 + 0.02 Single 2.38 + 0.20 0. 53 + 0.04 b1265.8 + 85.7 318.9 + 16.8 Weekly 2.58 +_ 0.26 0.54 + 0.05 b 1201.1 + 108.1 326.0 ± 22.3 Biweekly 2.63 + 0.23 0.55 LSR = 0.96 1. 2. 3. o • o +1 Check LSR = 0.20 at>1176.3 +_ LSR = 72. 2 372.08 313.1 + 36.7 LSR = 127. Values (X Hh SE) sharing superscripts are not significantly different at the .05 level, using the LSR test. Comparisons are only within a month. above ground living biomass in g • m “2 kg. nitrogen per hectare present in above ground biomass 25 Table 9. Treatment Number of plant species present. Values are the X of four replicates of each treatment. July1 August + 2.1 Single 17.25 + 1.2 17.25 + 1.3 b 12.25 + 1.3 10.75 + 0.9 b 22.50 + 0.5 Weekly 20.00 + 0.9 18.75 + 0.9 13.25 +_ 1.8 13.50 + 2.1 27.75 + 1.7 Biweekly 20.75 + 1.0 18.00 + 1.3 13.75 + 2.2 12.75 + 1.9 27.50 + 1.5 LSR = 2.23 0.9 a20.25 +1.0 a22.25 + 2.2 Peak 21.75 1. + October SE Check LSR = 6.50 a24.50 September hh aK LLSR = 7.31 LSR = 7.8 a32.75 + 2.0 LSR = 4.69 Values sharing superscripts are not significantly different at the .05 level, using the LSR test. Comparisons are only made within a month. 26 FIGURE 2. Number of plant species present {X + 2 SE) 27 I o Number of plant species 30H i 20 10H H i□o Ii TC) tt T i T To 0 -O .T Til -1A i Aj. 1 ill tI M O Treatment 1-check A — ii— 2~single □ —ii— 3'weekly 0 “ ,l"" 4-biweekly 1---------------- i— July August ° 0 111 ------------- 1 September October Time Figure 2. Peak 28 Table 10. Treatment — -2 Above ground biomass (X +_ SE) in g • m . Values were derived from four replicates of each treatment. August Check 231.9 + 51.9 418.2 + 78.1 a606.9 _ + 98.1 a523.5 + 91.8 Single 366.7 + 46.6 677.4 + 56.8 1093.5 _+ 78.5 776.4 + 55.5 Weekly 302.5 + 17.5 624.9 + 78.0 945.8 + 106.4 814.1 + 40.0 Biweekly 271.1 + 44.6 650.9 + 88.3 973.7 + 67.7 783.7 + 79.2 LSR = 142.69 1. LSR = 189.94 September October Juiy LSR = 208.74 LSR = 202.78 Values sharing superscripts are not significantly different at the .05 level, using the LSR test. Comparisons are only made within a month. 29 Table 11. Treatment Check Single Weekly Biweekly — _2 Below ground biomass (X +_ SE) in g • m . Values were derived from predicted below ground biomass in the four replicates of each treatment. July1 ai06.5 + 21.65 September aH 0 . 2 + 19.77 ai32.1 + 17.09 ab182.7 + 17.22 214.3 + October 17.58 251.5 + 13.35 220.0 + 11.69 197.1 + 32.48 205.3 + 26.78 240.1 + 21.17 236.7 + 35.68 196.7 + 30.14 C287.7 + 32.60 b275.2 + 37.32 225.7 + 25.65 318.5 + 48.28 LSR = 46.45 1. August LSR = 118.4 LSR = 100.4 LSR = 143.3 Values sharing superscripts are not significantly different at the .05 level, using the LSR test. Comparisons are only made within a month. 30 across treatments from July through September, while above ground plant biomass became more separated (diverged) in treatments compared to checks from July to September. A comparison of mean above ground biomass in each treatment at peak production showed checks to be significantly less (p 0.05) than single and weekly application treatments (Table B). Since only above ground portions of plant biomass are usually har­ vested, only these portions were evaluated in terms of nutrient accumula­ tion. Nutrient accumulation, expressed as kilograms of nitrogen per hec­ tare, was significantly greater (p <_ 0.05) in all treatments compared to checks in August, September and October. In July, only the single and weekly application treatments differed significantly from checks (Table 12). Nitrogen accumulation at peak standing crop (Table 8) again shows checks to be significantly less (p _<_ 0.05) than all other treatments. Kjeldahl nitrogen was monitored at ten soil depths in each treatment. Results (Tables A32-41) show, at the 0-10 centimeter depth, nitrogen in checks to be significantly less (p ments only in June. 0.05) than single application treat­ The only other point in time where significant differ­ ence in nitrogen were noted was in October at the 70-80 cm. depth. These data do indicate that the amount of Kjeldahl nitrogen present at the dif­ ferent soil depths monitored was the same in all treatments at a single depth at one sample date. Results for nitrate nitrogen analysis at each ten centimeters soil depth are summarized and significant differences are indicated in the tables (Tables A22-31). Graphing the mean values (Figures 3-6) for nitrate nitrogen in each treatment show that in the checks soil nitrate levels decreased over the season at all soil depths. The graph for the single 31 FIGURE 3. Mean Nitrate nitrogen (ppm.) for treatment one (check) at each 10 cm. soil depth for each time interval over the season Soil Depth (cm.) •• 30-40 60-70i "June "July AugSept. >#0 c t . 90-100 0 10 N i t r a t e N i t r o g e n C o n s e n t r a t i o n (p p m .) Figure 3. 33 FIGURE 4. Mean nitrate nitrogen (ppm.) for treatment two (single) at each 10 cm. soil depth for each time interval over the season 0-10 - - - *> Soil Depth (c g 30-40.......... 60-70- June 90-100— r~ 20 N itra te — j— 30 40 N itro g e n C o n c e n tra tio n (p p m ) Figure 4. 35 FIGURE 5 Mean nitrate nitrogen (ppm.) for treatment three (weekly) at each 10 cm. soil depth for each time interval over the season 0-10 i > / Soi I Depth (c 30-40- 60-70- 90-100”1 10 N itra te N itro g e n — I 20 C o n c e n tra tio n (ppm ) Figure 5. 37 FIGURE 6 Mean nitrate nitrogen (ppm.) for treatment four (biweekly) at each 10 cm. soil depth for each time interval over the season 38 o-io -• . - - i * # ‘3 0 -4 0 E u Q. 0> O o June — July Aug. ----- Sept. .... Oct. 60-70 (/) 90-100“i 10 N itra te — f— — r- — r~ 20 30 40 N itr o g e n C o n c e n tra tio n Figure 6. ^ppm ) 39 application response (treatment two) shows nitrate levels generally increased over time in the upper thirty centimeters with substantial amounts of nitrate building up in the ten to thirty centimeter zone in October. In the weekly and biweekly application treatments the build-up of nitrate in the ten to thirty centimeter zone became apparent in September and increased more by October. It is noteworthy that weekly and biweekly application treatments appear to have two periods of nitrate build-up in the ten to thirty centimeter zone, September and October, while the single application treatment had only one, occurring in October. DISCUSSION The Effect of Chronic and Single Nutrient Inputs on a First Year Fallow Plant Array Production Responses The production responses discussed here occurred during the 1972 growing season. Climatic data (U.S. Dept. Comm., 1972) indicate this season was more moist than average with annual rainfall equal to 37.38 inches, of which over half was received during the growing season. thirty year mean annual precipitation is 30.8 inches. The Consequently, soil moisture was not considered to have any great limiting effect on the re­ sponses discussed here. Compared to checks, fertilization increased above ground production by 54 percent in the single, 46 percent in the weekly, and 44 percent in the biweekly application treatments. The increased amount of nitrogen accumulated in vegetation (Table 12) of fertilized treatments also indi­ cates that more nitrogen was available for plant use in these treatments. The production responses measured in this study are presented along with the results of other studies in Table 13. By comparing the production values in Table 13 one can see that in the 6-year fallow field of Hurd et al., (1971) fertilization increased production by 97 percent, while in the 17-year fallow field production was increased 71 percent. In the first-year fallow fields of Stephenson (1973a) production was not increased in the early fallow fields while production was increased 138 percent in 40 41 Table 12. Treatment Nitrogen accumulation above ground in kg. per hectare (3T +_ SE) . Values were derived from the four replicates of each treatment. July^ August September a48.2 + 12.02 a66.7 + 11.57 a75.7 + Single b134.9 + 18.51 200.9 + 18.59 279.4 + 15.30 180.7 + Weekly b110.3 + 3.33 216.2 + 23.08 265.3 + 28.95 192.9 + 22.98 97.8 + 18.65 230.9 + 31.95 271.2 + 24.95 192.9 +_ 22.98 LSR = 56.0 LSR = 5 7 . 5 Check Biweekly 1. 6.25 October LSR = 86.11 a73.4 + 12.40 8.90 LSR = 47.7 Values sharing superscripts are not significantly different at the .05 level, using the LSR test. Comparisons are only made within a month. Table 13. Author Field Age Number of species 56 6 9.50 1314.0 56 17 18.00 784.0 0 6 10.25 669.0 0 17 17.50 402.0 Nitrogen Added (kg. • ha-^) Hurd et al. (1971) Stephenson (1973a) Reed (tis study) Field data comparison of results of this study with other studies. Production (g. • m^} 150 1 (early) 60 841.0 150 1 (late) 22 2116.4 0 1 (early) 49 855.5 0 1 (late) 30 886.6 450 once 1 23 1265.8 + 85.7 450 weekly 1 28 1201.1 + 108.1 450 biweekly 1 28 1176.3 + 72.2 1 33 0 820.8 + 146.4 Notes I have assumed a 150-day growing season here. early field was mainly cool season dicots (C ) 3 late field was mainly warm season grasses (C^) all at peak annual pri­ mary productivity at peak net annual primary productivity w 43 the late field that was fertilized. The lack of response in Stephenson's early fallow field was attributed to periodic drought conditions which occurred throughout the experimental period. From these data (Table 13) one can observe that, as a general rule, production is enhanced by the addition of nutrients. Here then, I have treated nitrogen as the control­ ling nutrient variable of production realizing that many other variables ultimately control this. Additionally, soil fertility analysis performed by the Michigan State University soil testing laboratory indicate that there were 33 pounds of available phosphorus and 182 pounds of potassium per acre in the experimental area. Neither of these nutrients was felt to be limiting for grass crops and as Black (1968) states, the supply of soil phosphorus, under practical conditions, cannot be exhausted within one growing season. It has been concluded that plants utilize two of these nitrogen forms, ammonium and nitrate ions (see Bartholomew and Clark, 1965; Black, 1968). Consequently, the addition of a large amount of available nitrogen in fertilizer, coupled with that supplied by the system itself, raised the site resources and consequently the production in the treatments. Since nitrate was one of the plant-available forms of nitrogen (Black, 1968; Viets, 1965) supplied to plants utilized in this research, I will confine my comments in this part of the discussion to soil nitrate beha­ vior. Although half the fertilizer nitrogen was in the ammonium form, ammonium ions are usually oxidized quickly by soil organisms (Nitrosomonas spp., Nitrobacter spp.) to nitrate (Alexander, 1961), thus making nitrate ion concentrations in the soil a good indicator of site resources with respect to nitrogen availability. Data (Figures 3-6) from this study indicates that nitrate concentration in the soil of unfertilized blocks 44 declined from June to August, increased in September, and declined in October. The increase in nitrates observed in September may have resulted from decomposition of plants that ceased growth in August, while the de­ crease in nitrates observed in October was associated with increased acti­ vity of Agropyron, which may have used the nitrates from September in the production of underground plant parts. Except for the large August value, the mean nitrate nitrogen concen­ trations in the upper thirty centimeters of soil increased through September in the single, weekly and biweekly application treatments {Figures 4-6). From September to October the amount of nitrate nitrogen in the upper ten centimeters declined in these treatments with the most pronounced effect being in the single and biweekly application treatments. Considering the upper thirty centimeters of the soil to be the active root uptake zone for nutrients for the plant array of this study, and considering the beha­ vior of underground biomass (Table 11), it is reasonable to assume that roots of plants in single, weekly and biweekly application treatments were in contact with more available nutrient (nitrate nitrogen) for a longer period of time than plants in check treatments. The large amount of residual nitrate nitrogen in soil of the single, weekly and biweekly application treatments (Figures 4-6) also suggest that if the vegetation had been harvested in late July, additional production could have been realized in these treatments if other conditions (H^O, temperature) for additional plant growth were met. It appears that plants in application treatments utilized the available nutrient resources (nitrate nitrogen) within the capability range of the plants present and that some other limiting resource such as light and/or space kept additional production from occurring. 45 Tho quantitative relationship between above-ground and below-ground primary production has received little attention in the ecological liter­ ature. Among the major problems in obtaining accurate estimates of root production are difficulties in sampling root biomass and the determination of consumption by soil animals. Estimates of both below-ground production and turnover rates have been made, exemplified by the study of Monk (1966). Monk (1966) describes the relationship between above and below-ground standing crop for 16 plant species, expressing this as the root/shoot ratio at a single point in time during the growing season. However, since this relationship changes as the plant matures, a single ratio does not provide an adequate estimate of root growth during an entire growing season. I have attempted here to describe the change in root/shoot ratio over the entire growing season and, by relating this to above-ground standing crop analysis, estimate belowground production on a unit area basis. The below-ground biomass estimates (Table 4) include some residual perennial plant materials produced during previous growing seasons. How­ ever, the two most abundant perennials, Agropyron repens and Sonchus asper, were neither individually nor collectively major components in any treat­ ment. Consequently, the error incurred from sampling old below-ground plant material is considered to be small. Therefore, these data (Table 11) pose some interesting questions that may be pertinent to the behavior of the vegetation of this study. These data (Table 11) indicate that with or without fertilization below-ground production, by vegetation of this study, is statistically the same in all treatments in September. This suggests that in first year fallow vegetation there is a maximum rootrhizome biomass. 46 These data also indicate that in the single, weekly and biweekly application treatments below-ground production reached this maximum bio­ mass earlier in the season than in the checks. This could indicate that fertilizer application enhanced under-ground production more rapidly, re­ sulting in increased nutrient uptake and consequently in greater above­ ground production. These data also indicate that individual species responded differently to the different treatments since total above­ ground production does not correlate with total below-ground production. This is certainly true for Agropyron (Tables A17-20) which was sampled separately in each treatment. Agropyron was sampled in this manner as McIntyre (1972) has demonstrated increasing nitrogen supply to Agropyron by the addition of NH^NO^ causes buds to produce shoots rather than rhi­ zomes. This occurred when McIntyre grew Agropyron in a solution containing 210 ppm. N a level lower than that in the soil solution of the upper soil zones in the single application treatment (Figure 4). Also, McIntyre re­ ports a gradient of differentiation response of buds along the rhizome as the nitrogen supply in the rhizome increases presumably as a result of increased nitrogen supply in soil solution. This situation, increased nitrogen supply in soil solution, was present in the weekly and biweekly treatments (Figures 5-6). Finally it could be that the combination of plants in the plant arrays studied caused the variation observed between treatments. Since these plants utilize about the same depth of substrate it could be that root-rhizome biomass realized in this vegetation would only occur again in early (first-year) fallow vegetation. Number of species Fertilization results in a decreased number of species in first year fallow vegetation (Table 9). Comparing these data with data of other 47 studies (Table 13) show this also occurred in other first year fallow vegetation. Again, the lack of response in Stephenson's early field was attributed to drought. This reduction in species number could be explained, in part, by the structure and life cycle (annual, biennial, perennial) of the vegetation present in the experimental plots. In this study the domi­ nant plant species were annuals, plants that responded rapidly to nutrient addition, and one perennial grass, Agropyron. The plant species responding most rapidly to nutrient addition were able to occupy the above and belowground space more rapidly in the treatments than in checks (Tables 10, 11). Thus, the plant array was essentially closed to additional species. An examination of Tables Al-16 indicates that rarer plant species (Oxalis stricta, Daucus carrota, Fanicum dichotomiflorum, Portulaca oleracea, Physalis spp., Melilotus officinalis) were some eliminated in fertilized arrays. Two of these species, Portulaca and Oxalis, do not attain any great height and all of these were late appearing and contributed little biomass in the checks. The loss of additional species in fertilized vege* tation was of longest duration in the single application (Table 9). This indicates that chronic application of nutrients, at levels used in this study, does not eliminate species to the same extent as single applica­ tion. One might suggest that fertilizer itself caused the elimination of species due to toxic chemical effects. However, most of the eliminated species are common agricultural weeds that exist in row crops receiving high fertilizer application. The relationship of number of species to production in successional and seasonal time has received some attention in recent years (McNaughton, 1968; Loucks, 1970; Hurd et al., 1971). this relationship has been reached. However, no agreement concerning In the geographic area of this study, 48 an inverse relationship was found between number of species and production during a single growing season. The relationship of the number of species acting as an independent variable controlling production has recently received criticism (Stephenson, 1973a). He states that it is production, acting as an independent variable which determines the number of species present. Data of this study tentatively support this hypothesis (Tables 9, 10) in first year fallow vegetation. Increased nutrients in the soil of treatment blocks allowed plants in these areas to express themselves earlier in the season through increased production, thus saturating the available growing space more rapidly. This would eliminate species from occupying open ground sites later in the season. Here then, over seasonal time, increased production from fertilization operated as the independent vari­ able that generated the number of species measured. Nutrient Accumulation Since in most waste water renovation programs the nutrient reclaimed in harvestable vegetation will be important, I will here discuss nutrient accumulation (nitrogen) in above-ground plant material. These data (Table 12) indicate that in this study the amount of nitrogen accumulated by above­ ground plant material in all fertilized treatment blocks was the same at all sampling dates. This indicates that the amount of nutrient uptake by plant material in treatment blocks is independent of the application sche­ dule. To examine the proportion of nitrogen reclaimed by the system in reference to that applied it is necessary to calculate the following: . . . (X N in tint) - (X N in checks) Tot. N added to tmt % reclaimed = ------ rr— — —— — — ■=— -— -— ------ At the time of greatest nitrogen accumulation in each treatment appli­ cation, September, the single applications reclaimed 45 percent, the 49 weekly 42 percent, and the biweekly 43 percent of the amount applied. At peak vegetation biomass the percent reclaimed was 47 percent, 48 per­ cent, and 45 percent in the single, weekly, and biweekly applications respectively. These data (Table 7) indicate that under any of the appli­ cation schedules followed the greatest quantity of harvestable nutrient in the system is present in September and amounts to approximately 270 kg. N. ha 1. The species of plant producing the plant material on a site will also have a great deal to do with the amount of nutrient taken into harvestable biomass. show that Data in this study (Table 2, Figure 7) plants (for a discussion of and plants see Black, 1970; Caswell et al., 1973) tend to contain higher quantities of nitrogen per gram of tissue than plants. This is in agreement with data of Wilson and Haydock (1971) working with tropical (C^) and temperate (C^) grasses in response to varying nitrogen levels. Expanding these results (Figure 7) to a large area, it would appear that plants as a group will take up more nutrient per unit area than two types is equal. Also, plants, providing production of the plants may be a poorer source of food for herbivores (Caswell et al., 1973) and thus make a poorer forage crop, although ruminants present a different situation than monogastric herbi­ vores. The amount of nitrate nitrogen accumulated by vegetation is also important if the vegetation is to be considered for use as forage. The acceptable level of nitrate in forage for consumption is 0.21 percent (Adriano, personal communication). Using the technique of Baker and Smith (1969) data in this study (Table 14) indicate that for the tested plant species present, plant material from checks would all be acceptable. In the weekly and biweekly application treatments only Agropyron has an acceptable nitrate level for forage, and this occurred only in July and August. 50 FIGURE 7 Kjeldahl nitrogen (X +_ 2SE) . Open symbols indicate species. Closed symbols indicate species. 51 O Treatment 1-check A ~ n“ 2-single □ — ii— 3-weekly 0 — ii— 4“biweekly July Aug. Sept. Time Figure 7. 52 Table 14. Treatment Check Single Weekly Biweekly Percent nitrate nitrogen present in vegetation in each treatment over time. Values were determined from one sample of plant material. Species September July August Agropyron repens Amaranthus retroflexus Chenopodium album Setaria spp. 0.007 0.096 0.052 0.046 0.006 0.006 0.015 0.002 0.003 0.007 0.003 Agropyron repens Amaranthus retroflexus Chenopodium album Setaria spp. 0.223 1.09 1.00 0.792 0.257 0.829 1.23 0.775 0.235 0.597 0.917 0.703 Aqropyron repens Amaranthus retroflexus Chenopodium album Setaria spp. 0.183 1.09 0.994 0.733 0.164 0.748 0.829 0.557 0.338 0.517 0.588 0.500 Agropyron repens Amaranthus retroflexus Chenopodium album Setaria spp. i 0.203 1.53 0.984 0.613 0.091 0.620 0.702 0.613 0.235 0.740 0.489 0.563 0.002 53 As Hlack (1970) states, plants are more efficient in their use of water, using less to produce a unit of biomass than quently, the use of tigation as C H plants. Conse­ plants in waste water renovation needs more inves­ plants, given an available water supply similar to C 3 plants, may be capable of producing more vegetation per unit area, and thus re­ moving more nutrient than plants. The data of Stephenson (1973a) (Table 9) from his late fallow fields indicates that greater quantities of vegetation per unit area than plants can produce plants. The plants accomplished this during a shorter growing period and thus the active period of nutrient uptake was shorter giving this system (C^) an overall shorter period for the distribution of waste water in a waste renovation system. The data of this study (Table 14, Figure 7) suggest, however, that at the present time plants are a poor choice for use on a spray irrigation site in the renovation of waste water effluent. A Spray Irrigation Area for Renovation of Secondary Effluent Terrestrial plant communities have been suggested as a means of reno­ vating waste water effluent (Sopper, 1971, Pennsylvania State). It appears that there are at least four important components of secondary effluent that will determine the effectiveness of natural plant communities in the renovation of secondary effluent. The first component is water. The move­ ment of water through porous media (soil) has been described by Novak (1972). Too much water applied to the soil in secondary effluent could saturate the root zone of plants, terminating root respiration, and thus killing the plants occupying the site. Other plants may take their place, but these may be less desirable for the renovation of effluent. Second, the amount of phosphorus present in effluent applications should be considered. 54 Phosphrus is adsorbed on clay soil particles (Alexander, 1961); the type and amount of clay present in the soil column above the water table will then determine how much phosphorus the system can adsorb. The total amount of phosphorus the system can adsorb coupled with the amount of phosphorus a plant array on the site can remove in successive years will then deter­ mine the life expectancy of the site if used for waste water renovation. Third, the amount of heavy metals present in the effluent will be impor­ tant. Since some plants tend to concentrate heavy metals (Antonovics, 1970) the amount accumulated by them may produce toxic levels in the vege­ tation and preclude its use as forage. However, it might be possible with modern technological methods to utilize plants to concentrate some heavy metals and then extract these from the plants. toward further investigation in this area. This certainly points Fourth, the amounts and forms of nitrogen in secondary effluent will have much to do with the success of a spray irrigation site. Nitrate nitrogen will be especially important in view of the fact that the anion is very mobile and tends to move through the soil column with water if not utilized by plants and/or soil microbes. A spray irrigation system for the renovation of secondary effluent must encompass the interactions that occur between soil, plants, and ani­ mals. Here, I have attempted to deal with one on these interactions, the soil and plants associated with it, using fertilizer as the forcing func­ tion. Nitrogen from secondary effluent can be introduced into the soil system in basically four forms; organic nitrogen, ammonium ions, nitrite ions, and nitrate ions. The form of nitrogen introduced is important in that it will determine the residence time of nitrogen in the active soil zones for root absorption. Organic nitrogen is trapped in the upper soil layers and must be converted to ammonium ions through the action of soil 55 microbes. The process of mineralization is slow (Alexander, 1961); conse­ quently, the nitrogen will be released slowly (Bartholomew, 1965). nium ions, already an available form for plant usq Ammo­ can be adsorbed by clay particles or through the process of aerobic bacterial nitrification oxi­ dized to nitrate. The rate at which these reactions take place is deter­ mined at least in part by abiotic factors (water, soil atmosphere, temper­ ature, pH) of the soil material. Also, the amount of nitrogen available for plant use from decomposition of organic matter will be a function of the carbon to nitrogen ratio in the vegetation and in the organisms decom­ posing the vegetation (Alexander, 1961). If the C/N ratio in plant material is high (>20:1) nitrogen from the decomposition process will be more immo­ bilized (a nitrogen limited system) while if the C/N ratio in plant material is low (<20:1) nitrogen will be mineralized more rapidly (a carbon limited system) (see Alexander, 1961; Burges and Raw, 1967; Cromack, 1972). Also, abiotic factors of substrate temperature, moisture and oxygen status will be important in the decomposition process (Witkamp, 1966, 1971). Finally, it is the fate of nitrate ions leached from active plant root zones that may determine the effectiveness of the site for use in water renovation of secondary effluent. These leached nitrate ions can only be removed from the system, without entering ground water, through the process of denitrification in the anaerobic soil zones (Tusneem and Patrick, 1971). This process is part of the entire processing system and needs more exten­ sive investigation in field situations if we are to understand and utilize denitrification. The form of nitrogen that appears to be most suitable for spray irri­ gation of secondary effluent is a mixture of organic nitrogen in conjunc­ tion with ammonium and nitrate ions. Organic nitrogen would be favored 56 since there is a slow release of available nitrogen from its breakdown. However, most secondary effluent contains very little organic nitrogen, suggesting that primary effluent may be more useful in spray irrigation. Also, the addition of an available carbon source to the effluent may lead to the utilization of available nitrogen by microbes and thus keep the nitrogen in the upper soil zones. This would change the C/N ratio in the substrate. If nutrients (nitrogen and phosphorous) are made available in large amounts at the beginning of the growing season in first year fallow vege­ tation, the plant species present early in the growing season will utilize them rapidly thus reducing or eliminating species that may commence growth at a later date. Consequently, over time (season) there will tend to be a reduction in the number of plant species (Table 9, Treatment 2). How­ ever, if nutrients are made available in pulses through a controlled irri­ gation schedule the loss in number of species over time (season) may not be as great (Table 9, Treatments 3,4). Therefore, in a spray irrigation system for the application of secondary effluent, the application schedule should bo arranged in such a manner to create asynchrony in the growth phases of plants in the plant array. This asynchrony (early season plants, late season plants) would then allow the active nutrient (nitrogen) accum­ ulation period in plants of the array to be extended beyond those in synchronous monocultures. As previously mentioned, the type of plant species supported by the site will be important especially in terms of C_ and C -3 plants, and possibly *» a balanced system could be created utilizing each of these groups in con­ junction with a harvesting schedule that opens the community for additional occupation by other plants. 57 After the production of plant material under spray irrigation with secondary effluent what does one do with the harvestable vegetation? If left on the spray site the material will decompose and may add to the already enlarged nutrient pool. If the plant material is harvested it might be used as forage, providing nitrate levels in the vegetation are not toxic to potential consumers. Also, the plant material could be used to improve poor and/or excessively well-drained soils (sand). As previ­ ously mentioned, if the C/N ratio in the vegetation is high (>20:1) decom­ position favors immobilization of nitrogen, and the addition of this plant material to poorer nutrient quality soils will also raise the organic matter content of the soil. Raising the organic matter content of the soil will increase the water holding capacity of the soil and may enable the area to support more vegetation. This aspect needs further investigation. Industrial use of this plant material produced on a waste water renovation site may also be an alternative, but research is just beginning in this area. However, it is apparent that some use must be found for this vege­ tation as it cannot be left on the spray site. Finally, some have suggested that spray irrigation using secondary effluent can be utilized in this region, for the renovation of waste water, throughout the year. I believe this needs further critical examination as it appears that winter application of effluent will only result in a build-up of available nutrient in the substrate which may favor species commencing growth early in the season. This would have an effect similar to single application treatments (treatment two). The use of terrestrial plant communities for the renovation of secon­ dary effluent requires a more detailed understanding of the behavior of the total system than we presently have. Therefore, I would suggest that waste water renovation programs be approached cautiously. 58 CONCLUSIONS In conclusion I believe that this study has brought out at least the following points: 1. Within a first year fallow field vegetation, as above-ground production increased through fertilization, the number of plant species decreased (Tables 9, 10). 2. Chronic application of fertilizer at low levels without harvesting increased production to the same extent as single applications (Table 9), provided the total amount of fertilizer applied is the same. Also, the number of plant species at peak net annual above ground production tends not to be reduced to the same extent in chronic application treatments as it was in the single application treatment (Table 9). 3. Over the growing season, C^ plants tend to accumulate more nitro­ gen per gram of tissue than C^ plants (figure V). 4. Nitrate nitrogen levels in vegetation from check communities was at a safe level for use of the vegetation as forage. However, in the single application treatment no vegetation was safe for use as forage. In the weekly and biweekly app't ication treatments only Agropyron in July and August had nitrate levels in the plant that would allow its safe use as forage (Table 14). 5. Under fertilization of 450 kg. N-ha ^ without water, using any of the application schedules of this study, the first year fallow plant array of this study accumulated in above ground vegetation an amount of nitrogen equal to about 45 percent of the amount of nitrogen applied. LITERATURE CITED LITERATURE CITED Adriano, D.C., F.H. Takatori, P.F. Pratt, and D.A. Lorenz. 1972a. Soil nitrogen balance in selected row-crop sites in Southern California. J. of Environ. Qual. 1:279-283. Adriano, D.C., P.F. Pratt, and F.H. Takatori. 1972b. Nitrate in unsaturated zone of an alluvial soil in relation to fertilizer nitrogen rate and irrigation level. J. of Environ. Qual. 1:418-422. Alexander, M. 1961. Introduction to soil microbiology. New York. 472 p. Wiley, Antonovics, J. 1970. Heavy metal tolerance in plants. p. 2-85. In Advances in Ecological Research. Vol. 7. Academic Press, New York. Baker, A.S. and R. Smith. 1969. Extracting solution for potentiometric determination of nitrate in plant tissue. Agr. and Food Chem. 17:1284-1287. Bartholomew, W.V. 1965. Mineralization and immobilization of nitrogen in the decomposition of plant and animal residues, ’p. 285-306. In Soil nitrogen. American Society of Agronomy, Madison, Wisconsin. Bartholomew, W.V. and F.E. Clark. 1965. ed., Soil Nitrogen. Society of Agronomy, Madison, Wisconsin. 615 p. Black, C .A. 1965. Soil-Plant Relationships. Inc., New York. 792 p. American John Wiley and Sons, Black, C.C. 1970. Ecological implications of dividing plants into groups with distinct photosynthetic production capatities. p. 87-114. In Advances in Ecological Research. Vol. 7. Academic Press, New York. Bormann, F.H., G.E. Likens, D.W. Fisher, and R.S. Pierce. 1968. Nutrient loss accelerated by clear cutting of a forest ecosystem. Science 159:882-884. Burges, A. and F. Raw (ed.) 1967. New York, X + 532 p. Soil Biology. AcademicPress, Caswell, H., F.C. Reed, S.N. Stephenson and P.A. Werner. 1973. Photo­ synthetic pathways and selective herbivory: a hypothesis. - Amer. Nat. 107:465-480. Connell, J.H., and E. Orias. 1964. The ecological regulation of species diversity. Amer. Nat. XCVIII:399-414. 59 60 Cooke, G.D. , R.J. Beyers and E.P. Odum. 1968. The case for the multispecies ecological system, with special reference to succession and stability, p. 129-139. In_ Bioregenerative Systems. Savannah River Ecology Laboratory, Univ. of Georgia. Cromack, K. Jr., 1972. Litter production and litter decomposition in a mixed hardwood watershed and in a white pine watershed at Coweeta Hydrologic Station, North Carolina. EDF Memo Report 72-159. Daubenmire, R. 1972. Standing crops and primary production in Savanna derived from semideciduous forest in Costa Rica. Bot. Gaz. December, 1972. 395-401. Gleason, H.A. 1968. The New Britton and Brown illustrated flora of the Northeastern United States and adjacent Canada. Hafner Publishing Company, Inc., New York. 3 vol. Golley, F.B. and J.B. Gentry. 1966. A comparison of variety and standing crop of vegetation on a one-year and a twelve-year abandoned field. Oikos 15:185-199. Hall, D.J., W.E. Cooper, and E.E. Werner. 1971. An experimental approach to the production dynamics and structure of fresh water animal communities. Limnol. and Oceanogr. 15:839-928. Hurd, L.E., M.V. Mellinger, L.L. Wolf and S.J. McNaughton, 1971. Stability and diversity at three trophic levels in terrestrial successional ecosystems. Science 173:1134-1136. Law, J.P., Jr., 1968. Agricultural utilization of sewage effluent and sludge: an annotated bibliography. U.S. Dept. Int. 89 p. Leigh, E.G., Jr. 1965. On the relation between the productivity, biomass, diversity and stability of a community. Proc. N.A.S. 53:777-783. Likens, G.E., F.H. Bormann, N.M. Johnson, and R.S. Pierce. 1967. The Ca, Mg, K, and Na budgets for a small forested ecosystem. Ecology 48:772-785. Likens, G . F . , F.H. Bormann, N.M. Johnson, D.W. Fisher, and R.S. Pierce. 1970. Effects of Forest Cutting and Herbicide Treatment on Nutrient Budgets in the Hubbard Brook Watershed Ecosystem. Ecol. Monog. 40:23-47. Loucks, O.T. 1970. Evolution of diversity, efficiency and community stability. Am. Zoologist 10:17-25. Margalef, D.R. 1968. Perspectives in ecological theory. Chicago Press, Chicago. Ill p. Univ. of 61 MacArthur, R.H. 1972. New York. 269 p. Geographical ecology. Harper and Row, Margalef, R.D. 1969. Diversity and Stability: A practical proposal and a model of interdependence, p. 25-37. In_ Brookhaven Sympo­ sium, No. 22, Diversity and Stability in ecological Systems. Brookhaven National Laboratory, Upton, New York. McIntyre, G.I. 1972. Studies on bud development in the rhizome of Agropyron repens. II. The effect of the nitrogen supply. Can. J. of Bot. 50:393-401. McNaughton, S.J. 1968. Structure and function in California grass­ lands. Ecology 49:962-972. Monk, C.D. 1966. Ecological importance of root/shoot ratios. Bull-Torrey Bot. Club 93:402-406. Monk, C.D. 1967. Tree species diversity in eastern deciduous forest with particular reference to N. Central Florida. Amer. Natur. 101:173-187. Novak, L.T. 1972. A simulation of two phase water movement in soil. 1972 Proceedings of Summer Simulation Conference San Diego, California (in press). Pavlychenko, T.K. 1937. Quantitative study of the entire root systems of weed and crop plants under field conditions. Ecology 18:62-79. Pielou* E.C. 1969. An Introduction to Mathematical Ecology. Wiley-Interscience, New York. 285 p. Root, R.B. 1973. Organization of a plant-arthropod association in simple and diverse habitats: the fauna of collards (Brassica olsracea), Eeol. Monog. 43:95— 124. Schneider, I.F. and A.E. Erickson. 1972. Soil limitations for dis­ posal of municipal waste waters. Research Report 195. Michigan State University, East Lansing. 54 p. Singh, J.S. and R. Misra. 1969. Diversity, dominance, stability, and net production in the grasslands at Varanasi, India. Can. J. Bot. 47:425-427. Sokal, R.R. and F.J. Rohlf. 1969. Biometry. The principles and practice of statistics in biological research. W.H. Freeman and Co., San Francisco. 776 p. Sopper, W.E. 1971. Effects of trees and forests in neutralizing wastes. In Trees and forests in an urbanizing environment. Cooperative Extension Service, Univ. of Mass., Amherst, Mass. 62 Stephenson, S.N. 1973. A comparison of productivity and diversity in early and late season oldfield plant communities. Mich. Acad. 5:325-334. Tusneem, M.E. and W.H. Patrick, Jr., 1971. Nitrogen Transfer Nations in Waterlogged Soil. Louisiana State Univ., Depart, of Agron., Bulletin No. 657. Whittaker, R.H. 1969. Evolution of diversity in plant communities, p. 178-196. In Brookhaven Symposium, No. 22, Diversity and stability in ecological systems. Brookhaven National Laboratory, Upton, New York. Wilson, J.R., and K.P. Haydock. 1971. The comparative response of tropical and temperate grasses to varying levels of nitrogen and phosphorous nutrition. Australian J. Agr. Res. 22:573-587. Witkamp, M. 1966. Decomposition of leaf litter in relation to environment, microflora and microbial respiration. Ecology 47:194-201. Witkamp, M. 1971. Soils as components of ecosystems, p. 85-110. In R.F. Johnston, P.W. Frank and C.D. Michener (ed.) Annual review of ecology and systematics, Vol. 2. Annual Reviews, Inc., Palo Alto, California. IX + 510 p. APPENDIX 63 Tables Al-16. Summary of the biomass contributed to above ground produc­ tion by each species at each interval in time over the season. Check communities were blocks 4, 5, 11 and 14. Single application treatments were blocks 3, 6, 9 and 16. Weekly applications were in blocks 2, 7, 12 and 13. Bi­ weekly applications were in blocks 1, 8, 10 and 15. 64 Table A1. Summary of Block 1. Biomass above ground contributed by each species at each sample period (g • m-^). Species Agropyron repens Amaranthus retroflexus Ambrosia artemisiifolia Barbarea vulgaris Chenopodium album Cirsium vulgare Cyperus esculentus Daucus carrota Digitaria sanguinalis Echinochloa crusgalli Euphorbia spp. Lychnis alba Medicago sativa Medicago lupilina Melilotus officinals Panicum capillare Phalaris arundinacea Poa compressa Polygonum convulvulus Polygonum pensylvanicum Polygonum persicaria Portulaca oleracea SeLaria glauca Setaria viridis Solidago canadensis Taraxacum officinale Thlaspi arvense Trifolium repens Verbascum blattaria Unknown July August 117.2 6.3 0.4 0.1 ilt.1 220.5 15.0 12.83 0.03 September 226.9 62.5 111.6 2.6 Octobe: 158.0 26.1 0.15 12.5 1.1 0.5 6.8 9.9 0.1 0.2 0.03 0.03 0.03 0.8 0.4 5.63 6.5 3.7 3.2 0.5 0.1 12.7 13.7 0.23 0.1 0.03 26.7 0.4 1.4 9.0 1.4 0.4 28.2 2.0 0.4 20.0 64.1 4.0 74.5 0.6 0.1 28.9 59.9 85.0 210.2 0.23 0.7 0.03 0.4 0.1 0.03 22.1 0.3 52.1 15.2 0.25 0.9 178.8 6.0 28.3 45.9 0.9 0.66 65 Table A2. Summary of Block 2. Biomass above ground contributed by each species at each sample period 7.44 + 2.23 5.58 LSR = 4.36 5.10 LSR = LSR = 27.12 87 Table A25. June July Depth 30-40 cm. August 1 1.49 + 0.59 1.16 + 0.13 0.78 + 0.10 0.81 + 0.30 2 1.22 + 0.34 3.28 + 1.48 2.39 + 1.02 3 1.26 +_ 0. 33 1.62 + 0.22 0.78 + 0.24 2.64 ± °*95 9.25 + 3.35 4 1.72 + 0.65 1.45 + 0.18 1.04 + 0.08 3.14 + 1.19 LSR = 1.82 LSR = 3.79 LSR = 2.18 LSR = 9.28 Table A26. mt June July Depth 40-50 cm. August September X 1.25 + 0.26 1.09 + 0.15 0.70 + 0.04 0.78 + 0.24 2 1.48 + 0.51 2.07 + 0.53 1.45 + 0.47 1. 53 + 0.59 3 1.78 + 0.35 1.44 + 0.36 1.01 + 0.51 1.40 + 0.27 4 2.35 + 1.32 1.41 + 0.16 1.42 +_ 0.48 1.41 + 0.34 LSR = 3.29 LSR = 1.48 LSR = 2.05 LSR = 2.02 Table A27. mt June July Depth 50-60 cm. August September 1 1.42 + 0.40 1.13 + 0.12 0.80 + 0.19 1.29 + 0.18 2 3.91 + 1.55 2.68 +_ 0.80 1.66 + 0.31 1.22 +_ 0.33 3 1.43 + 0.16 1.18 + 0.06 1.16 + 0.45 1.46 +_ 0.24 4 2.71 + 1.01 1.46 + 0.23 0. 96 0. 06 1.16 +_ 0.17 LSR = 4.10 LSR = 1.99 LSR = 1.04 LSR = 0.58 Table A28. nt June July Depth 60-70 cm. August September 1 1.25 + 0.15 1.27 + 0.26 1.20 + 0.19 0.82 + 0.11 2 1.59 + 0.51 2. 66 +_ 0. 53 0.98 + 0.11 1.02 + 0.16 3 1.23 + 0.23 1.38 + 0.23 0.92 + 0.07 1.28 + 0.27 4 1.77 + 0.43 1.93 + 0.28 1.06 +_ 0.09 1.13 + 0.19 LSR = 1 .22 LSR = 1 . 9 4 LSR = 0.69 LSR = 0.80 88 Table A29. Tmt July June Depth 70-80 cm. August September 1 2.06 + >.66 1.14 ± 0.10 1.44 + 0.34 0.95 + 0.23 2 6. 34 + :.69 2.41 + 0.50 1.23 + 0.22 0.98 + 0.15 3 2.48 +_ l'.45 1.43 + 0.17 0.94 + 0.20 1.47 + 0.25 4 2.02 1.97 0.61 1.02 +_ 0.13 1.76 + 0.71 LSR = 1 . 9 2 LSR = 0.91 LSR = 1.81 0 .71 LSR = 3 .59 Table A30. mt July June Depth 80-90 cm. August September 1 1 .21 +_ 0 .18 1.43 + 0.08 1.50 ± 0.38 0.86 + 0.13 2 1.87 +_ 0 .58 2.53 + 0.88 0.92 + 0.09 1.38 + 0.28 3 1.74 + 0 .27 2.02 + 0.72 1.22 + 0.22 1.24 + 0.07 4 1.91 +_ 0 .58 1.83 + 0.23 0.88 + 0.07 1.33 + 0.06 LSR = 1 .56 LSR = 1.82 LSR = 1.21 LSR = 0 . 5 4 Table A31. mt July June Depth 90-100 cm. August September l 1 •1? + 0 .22 1.60 + 0.33 1.21 ± 0.36 1.06 + 0.10 2 2.39 + 1 H O ■ 2.75 +_ 0.42 0.92 + 0.02 1.11 + 0.17 3 1.48 + 0 .16 1.79 + 0.48 1.04 + 0.28 1.27 +_ 0.09 4 2.14 + 0 .77 1.60 + 0.15 0.82 + 0.04 1.14 + 0.04 LSR = 2 .73 LSR = 1.59 LSR = 1 . 3 8 LSR = 0.58 89 Tables A32-A41. Percent Kjeldahl nitrogen (X SE) in soil increments of 10 cm. from 0-100 cm. depth. Values sharing superscripts are not significantly different at the 0.05 level. LSR values from Tukey's test and are compared only within a time period and depth. 90 Table A32. June Tmt July Depth 0-10 cm. August September ± 0.01 0.135 + 0.01 0.142 + 0.01 0.127 + 0.02 0.165 + 0.01 0.157 + 0.01 0.157 + 0.01 0.136 + 0.01 3 0.147 + 0.01 0.162 + 0.01 0.152 + 0.01 0.150 + 0.01 4 ab0.140 + 0 .01 0.160 + 0.01 0.157 + 0.01 0.132 + 0.01 1 2 a0.120 _V LSR = 0.025 LSR = 0.040 Table A33. Tmt June July LSR = 0.051 LSR = 0.082 Depth 10-20 cm. August September 1 0.090 + 0.02 0.130 + 0.01 0.125 + 0.01 0.125 + 0.03 2 0.107 + 0.01 0.132 _+ 0.01 0.130 + 0.01 0.153 + 0.01 3 0.107 ■+ 0.02 0.142 +_ 0.01 0.137 + 0.01 0.135 + 0.02 4 0.102 + 0.01 0.160 + 0.01 0.135 + 0.01 0.130 + 0.01 LSR = 0.065 LSR = 0.056 Table A 34. Tmt June July LSR = 0.042 LSR = 0.094 Depth 20-30 cm. August September 1 0.067 +_ 0.01 0.070 + 0.01 0.052 + 0.01 0.061 + 0.01 2 0.077 +_ 0.01 0.060 + 0.01 0.095 + 0.03 0.111 + 0.02 3 0.080 +_ 0.02 0.077 +_ 0.02 0.090 + 0.03 0.082 + 0.02 4 0.075 + 0.01 0.092 + 0.01 0.065 + 0.01 0.052 + 0.01 LSR = 0.035 LSR = 0.070 Table A35. rmt June July LSR = 0.089 LSR = 0.094 Depth 30-40 cm. August September 1 0.047 + 0.01 0.037 + 0.00 0.040 + 0.01 0.038 + 0.01 2 0.045 + 0.01 0.047 + 0.01 0.040 + 0.01 0.042 + 0.01 3 0.047 + 0.01 0,052 + 0.01 0.037 + 0.01 0.050 + 0.01 4 0.035 +_ 0.00 0.050 + 0.01 0.045 +_ 0.01 0.037 + 0.01 LSR = 0.025 LSR = 0.043 LSR = 0.041 LSR = 0.050 91 Table A36. Tmt June Depth 40-50 cm. August September 1 0.047 + 0.01 J-ulV 0.035 + 0.00 2 0.030 + 0.01 0.045 + 0.01 0.035 + 0.01 0.032 + 0.01 3 0.052 + 0.01 0.032 + 0.00 0.030 + 0.01 0.032 +_ 0.01 4 0.035 + 0.01 0.042 + 0.01 0.042 + 0.01 0.027 + 0.01 LSR = 0.035 LSR = 0.027 Table A37. "Rut June July 0.027 + 0.01 0.026 +_ 0.01 LSR = 0.033 LSR = 0.038 Depth 50-60 cm. August September 1 0.045 +_ 0.01 0.025 +_ 0.00 0.027 + 0.01 0.028 + 0.01 2 0.032 + 0.01 0.042 + 0.01 0.037 ±_ 0.01 0.027 + 0.01 3 0.037 0.027 +_ 0.00 0.032 + 0.00 0.027 + 0.01 4 0.042 + 0.01 0.045 0.045 + 0.01 0.030 +_ 0.01 0.01 LSR = 0.035 0.01 LSR = 0.031 Table A38. Tmt June LSR = 0.020 LSR = 0.036 Depth 60-70 cm. August 1 0.037 +_ 0.01 July 0.035 + 0.01 2 0.030 +_ 0.01 0.037 +0.01 0.045 + 0.01 0.020 + 0.01 3 0.027 +_ 0.01 0.027 + 0.01 0.030 + 0.01 0.032 + 0.01 4 0.032 + 0.00 0.037 +_ 0.01 0.030 + 0.01 0.025 + 0.01 LSR = 0.025 LSR = 0.025 0.025 + 0.01 0.027 + 0.01 LSR = 0.020 LSR = 0.022 92 Table A39. Tmt June July Depth 70-80 cm. August £ September 1 0.040 + 0.00 0.032 + 0.01 0.022 0.01 0.023 + 0.01 2 0.035 +_ 0.01 0.035 + 0.01 0.035 +_ 0.01 0.027 + 0.01 3 0.032 +_ 0.01 0.027 + 0.01 0.032 +_ 0.00 0.037 + 0.00 4 0.032 + 0.01 0.037 + 0.01 0.040 + 0.01 0.020 + 0.01 LSR = 0.025 LSR = 0.027 Table A40. Tmt June July LSR = 0.022 LSR = 0.040 Depth 80-90 cm. August September 1 0.027 + 0.01 0.032 + 0.01 0.020 + 0.01 0.016 + 0.00 2 0.040 + 0.01 0.035 + 0.00 0.035 + 0.01 0.030 + 0.01 3 0.030 + 0.01 0.030 +_ 0.01 0.025 + 0.00 0.027 + 0.01 4 0.025 + 0.01 0.037 + 0.01 0.032 + 0.01 0.017 + 0.01 LSR = 0.017 LSR = 0.022 Table A41. Tmt June July LSR = 0.022 LSR = 0.023 Depth 90-100 cm. Auqust September 1 0.025 + 0.00 0.030 + 0.01 0.020 + 0.01 0.011 + 0.01 2 0.035 + 0.01 0.027 + 0.01 0.022 + 0.01 0.022 + 0.01 3 0.027 + 0.01 0.017 + 0.00 0.027 + 0.00 0.022 + 0.01 4 0.025 + 0.00 0.030 + 0.01 0.032 + 0.01 0.022 + 0.01 LSR = 0.023 LSR = 0.017 LSR = 0.019 LSR = 0.013