v—WV: 4m 7. . .3 3 vuxamgsnx. e N {3N [0M ATS! i" 5N7. NW 'NfiXRl PCB Ngflxnnfimvm,NmaNEFH...Nwfimfizfiw“figfifigfinfifik..é..%fi...& . .5. :2 N A.» abémfifiaagp; .. .1 2.5.1.5»: 7!: .I: .1: This is to certify that the thesis entitled Effect Of 8011 Heavy Metal Contamination Upon Growth And Nutrient Composition 0f Corn presented by Richard Henry Leep has been accepted towards fulfillment of the requirements for Ph.D. , Soil Science degree in I Major professor Date m— 0-7639 Home av a, aoox amnrmi RARY BINDERS ABSTRACT EFFECT OF SOIL HEAVY METAL CONTAMINATION UPON GROWTH AND NUTRIENT COMPOSITION OF CORN BY Richard Henry Leep A greenhouse study was conducted using a Houghton muck (pH 6.7), treated with CdClZ, CrC13, NiCl and ZnCl2 and 2 crOpped with corn. Cadmium and Cr were applied in equal milliequivalent concentrations ranging from 0.05 to 2.0 milliequivalents of metal/100 9 soil. Nickel and Zn applications ranged from 0.1 to 9.0 milliequivalents metal/100 9 soil. Treatments were replicated four times and a control set was included. After harvest, corn plants and soil samples were analyzed for Cd, Cr, Cu, Fe, Mn, Ni, and Zn by atomic absorption SpectrOphotometry. Plant samples were analyzed for Ca, K, Mg, and P by emission spectroscopy. Plant growth and heavy metal uptake was influenced quite differently by Cd, Cr, Ni, and Zn. Additions of Cd caused delayed seedling emergence, stunting of plants, and plant dry weight reduction. Cadmium accumulation in plant tissue increased significantly with graded additions of Cd. Richard Henry Leep Plants grown on Cr treated soil yielded significantly higher in dry weight compared to the control. However, a subsequent chemical analysis of plant tissue revealed no detectable Cr. Significantly higher levels of Mn were detected in the plant. Graded additions of Ni up to 3.0 meq/100 g increased plant growth significantly over the control. Rates of Ni above 3.0 meq/lOO 9 reduced plant growth significantly in- dicating a probable Ni toxicity. The plants accumulated Ni in relatively high amounts. Plant size was similar to the control on all Zn treat- ments. Zinc accumulation in plant tissue up to 1763 ppm indicates that Zn was readily available for plant uptake. The soil extractants varied greatly in their ability to extract metals from the soil. Both 0.1 N HCl and 0.005 M DTPA worked well in extracting heavy metals and were about equal in amounts extracted. 1 N_NH4OAc was somewhat less effective than 0.1 N_HC1 and 0.005 M DTPA in terms of amount of metal extracted, however, each extractant removed increas- ing amounts of metals corresponding to graded additions of metals with the exception of Cr additions in which only 0.1 N HCl removed Cr. EFFECT OF SOIL HEAVY METAL CONTAMINATION UPON GROWTH AND NUTRIENT COMPOSITION OF CORN BY Richard Henry Leep A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of CrOp and Soil Sciences 1974 To Judith ii ACKNOWLEDGMENTS The author wishes to express his sincere gratitude to Dr. B.D. Knezek for his guidance, encouragement, and patience throughout this investigation and thesis preparation. His personal concern and interest in planning my academic pro- gram will forever be appreciated. Graditude is also expressed to Drs. B.G. Ellis, B.G. Doll, and A.R. Wolcott for their suggestions during the investigation and preparation of the thesis. Appreciation is extended to Mrs. Betsy Bricker and Mrs. Corrintha Dekker for their assistance with laboratory and statistical analysis of data. The author is grateful to his guidance committee: Dr. B.G. Doll, Dr. C.L. Humphrys, Professor I.F. Schneider, and Dr. A.R. Wolcott for their c00peration and valuable comments during the course of this study. To the other faculty members and fellow graduate stu- dents in the Soil Science Department who assisted during this study go my sincere appreciation. The financial assistance provided by the Tennessee Val- ley Authority under contract number TV-30410A and agreement Michigan 1131-74 is gratefully acknowledged. iii TABLE OF CONTENTS page LIST OF TABLES O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O I O 0 Vi LIST OF FIGURES O O O O O O O O O O O O O O O O O O O O O O O 0 O O O O O O C O O O O O O O O Viii LIST OF PLATES O..OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO ix I-‘ INTRODUCTION OOOOOOOOOOOOOO00.0.0000...OOOOOOOOOOOOOOOO REVIEW OF LITERATURE 0.000000000000000000000000.0.0.... Cadmium in Soil .................................. Role of Cadmium in Plants ........................ Chromium in Soil ................................. Role of Chromium in Plants ....................... Nickel in Soil ................................... 11 Role of Nickel in Plants ......................... 13 Zinc in Soil ..................................... 15 Role of Zinc in Plants ........................... 16 ~0qu 0) EXPERIMENTAL mmODS OOOOOOOOOOCOOOOOOOO0.000000000000. 19 Greenhouse Studies ............................... 19 Plant Analytical Methods ......................... 20 Soil Analytical Methods .......................... 21 Soil pH ..................................... 21 Extractable Cadmium, Chromium, COpper, Iron Manganese, Nickel and Zinc ................ 21 Statistical Procedures ........................... 23 RESULTS AND DISCUSSION OOOOOOOOOOOOOCOO...0.00.00.00.00 24 Effect of Increasing Concentrations of Soil Applied Cadmium upon Growth, Yield, and Nutrient Compo- sition of Corn ................................. 24 Influence of Increasing Soil Cadmium Concentra- tions upon Soil Extractable Metal Concentrations 31 Effect of Increasing Concentrations of Soil Applied Chromium upon Plant Growth, Yield, and Nutrient Composition of Corn ................... 34 Influence of Increasing Soil Chromium Concentra- tions upon Soil Extractable Metal Concentra- tions .0....OOOOOOOOOOOCOOOOOOOOOCO0.0.0.0000... 41 iv TABLE OF CONTENTS - Continued page Effect of Increasing Concentrations of Soil Applied Nickel upon Plant Growth, Yield, and Nutrient Composition of Corn .................... 41 Influence of Increasing Soil Nickel Concentra- tions upon Soil Extractable Metal Concentra- tions ........................................... 50 Effect of Increasing Concentrations of Soil Applied Zinc upon Growth, Yield, and Nutrient Composition of Corn ............................. 57 Influence of Increasing Soil Zinc Concentration upon Soil Extractable Metal Concentrations ...... 66 SUMMARY AND CONCLUSIONS 0.0.0....OOOOOOOOOOOOOOOOOOOOOOO 69 LITERATURE CITED OOOOOOOOOOOOOOOOOOOOO0......00.....0... 72 Table 1. 10. 11. LIST OF TABLES Chemical prOperties of a Houghton muck soil from the Michigan State University Experimental Muck Farm. CO...0.0.0.0...I....00....OOOOOOOOOOOOOOOOOO Soil extraction procedures. ...................... Yields of dry matter and metal content of corn plants grown on Houghton muck after graded additions 0f caMiumO OOOOOOOOOOOOOOOOOOOO0......O Yields of dry matter and nutrient content of corn plants grown on Houghton muck after graded additions Of caMium. OOOOOOOOOOOOOOOOOOOO00...... Extraction behavior of selected metals in Houghton muck after graded additions of cadmium followed by cropping With corn. 00.0.0.0...OOOOOOOOOOOOOOOOOOO Yields of dry matter and metal content of corn plants grown on Houghton muck after graded additions Of Chromimn. OOOOOOOOOOOOOOOOO0.0.0.0... Yields of dry matter and nutrient content of corn plants grown on Houghton muck after graded additions Of Chromim. 0......OOOOOOOIOOOOOOOOOOOO Extraction behavior of selected metals in Houghton muck after graded additions of chromium followed by crOpping with corn. ........................... Yields of dry matter and metal content of corn plants grown on Houghton muck after graded additions Of niCRel. OOOOOOOO0.000000000000000000. Yields of dry matter and nutrient content of corn plants grown on Houghton muck after graded additions Of niCkel. OOOOOOOOOOOOOIOOOOOOO00...... Extraction behavior of selected metals in Houghton muck after graded additions of nickel followed by cr0pping with corn. .............................. vi page 22 23 29 30 32 39 40 46 48 49 55 LIST OF TABLES — Continued Table 12. 13. 14. page Yields of dry matter and metal content of corn plants grown on Houghton muck after graded additions Of zinc. OOIOOOOOOOOOOOOOOOOOO0000...... 64 Yields of dry matter and nutrient content of corn plants grown on Houghton muck after graded additions Of Zine. .00...0.0.0.0...OOOOOOOOOOOO... 65 Extraction behavior of selected metals in Houghton muck after graded additions of zinc followed by crepping With corn. OOOOOOOOOOOOOOOOOOOO0.0.0.0... 67 vii LIST OF FIGURES Figure page 1. Yields of dry matter and cadmium content of corn plants grown on Houghton muck after graded additions of cadmium. ............................ 28 2. Yields of dry matter and manganese uptake of corn plants grown on Houghton muck after graded additions of chromium. ........................... 38 3. Yields of dry matter and nickel content of corn plants grown on Houghton muck after graded additions of nickel. ............................. 45 4. Yields of dry matter and copper uptake of corn plants grown on Houghton muck after graded additions of nickel. ............................. 52 5. Yields of dry matter and manganese uptake of corn plants grown on Houghton muck after graded additions of nickel. ............................. 54 6. Yields of dry matter and zinc content of corn plants grown on Houghton muck after graded additions Of Zinc. 00......OOOOOOIOOOOOOOOIO...0.. 61 7. Yields of dry matter and copper uptake of corn plants grown on Houghton muck after graded additions Of Zine. 000......OOOOOOOOOOOOOOOOIOOOOO 63 viii LIST OF PLATES Plate page 1. Photograph showing growth of corn plants grown on Houghton muck after graded additions of cadmium. . 26 2. Photograph showing growth of corn plants grown on Houghton muck after graded additions of chromium. 36 3. Photograph showing growth of corn plants grown on Houghton muck after graded additions of nickel. . 43 4. Photograph showing growth of corn plants grown on Houghton muck after graded additions of zinc. .... 59 ix INTRODUCTION The public is becoming increasingly concerned with the pressing problems of municipal or industrial waste diSposal and possible entry of toxic materials into waterways. This concern has prompted municipalities, government agencies, and universities to investigate alternative methods of dis- posal. One alternative method which has received much attention is land disposal or the spreading of urban wastes onto agricultural land. The practice of spreading wastes onto land has been used for many years on a limited scale. Much of the research on the use of sludges or wastes for agricultural land has been concerned with the fertilizing value of the materials. How- ever, many sludges or wastes contain substantial quantities of heavy metals (Cd, Cr, Cu, Ni, and Zn) which are toxic to living organisms. Cadmium in all its chemical forms is toxic to living species (Fulkerson and Goeller, 1973). Plants grown on soil amended with Ni resulted in severe plant toxicities and growth retardation (Crooke, 1955; Traynor, 1974; Vanselow, 1966). Chromium has been seen to be toxic to many species of plants (Pratt, 1966; Soan and Saunder, 1959; Schueneman and Ellis, 1973). Zinc is considered an essential element for plant 1 growth, however, excessive accumulation of Zn can cause a Zn toxicity (Melton, 1968). The extent to which heavy metals are inactivated for plant uptake may vary greatly from soil to soil, depending upon cation exchange capacity, percent organic matter, clay content, and pH (Haghiri, 1974; John, 1972; Traynor, 1974). Heavy metals contained in many sewage sludges are po- tentially toxic to plants. This study was initiated to evaluate effects of graded additions of Cd, Cr, Ni and Zn on grown of corn plants on a Houghton muck soil. Yields of dry matter, and metal and nutrient contents of the plants, were determined. The extraction behavior of selected metals was studied to throw some light on mechanisms for their inactiva- tion in soil. REVIEW OF LITERATURE Cadmium in Soil Lagerwerff (1972) discussed the presence of Cd in the soil. He has found that the presence of Cd is normally linked to that of Zn because of their geochemical kinship and incomplete technical separation. Parent rock materials of basaltic origin have a higher concentration of Cd than those of granite rocks (Traynor, 1974). Total concentrations of Cd typically found in soils average 0.06 ug Cd/g soil with a range of 0.01 to 7.0 ug Cd/ 9 soil (Allaway, 1968). Cadmium may reach the soil as an aerosol constituent, through precipitation or direct deposition. Direct deposi- tion may occur near factories or mines handling Zn. Cadmium is also deposited in soils as an impurity in phosphate fer- tilizers, or as a constituent of certain fungicides which are sprayed onto crops (Lagerwerff, 1972). Cadmium in roadside plants and soils, decreasing with distance from the traffic, was attributed to Cd as an impurity in Zn containing addi- tives in motor oils and Zn compounds used in vulcanization of rubber tires (Lagerwerff and Specht, 1970). Sewage sludges used in land waste disposal may contain relatively high amounts of Cd, depending on the area or location the sludge 3 comes from. John (1972) has described Langmuir adsorption isotherms for 30 soils from British Columbia. He determined the ad- sorption maximum and a coefficient relating to the bonding energy of the soil for Cd. The adsorption maxima for all soils were similar in magnitude and correlated with Al and Zn soluble in 0.01 5 CaCl The coefficient related to the 2. bonding energy generally decreased in the order: organic> heavy clay>sandy and silt loam>sandy soils. Ellis and Knezek (1972) have reviewed literature per- taining to relationships of various metals and soil organic matter as well as known and proposed mechanisms by which metals are adsorbed by organic matter. Stability diagrams for chelates of Cd++ have been pre- sented by Norvell (1972) to illustrate one method of estima- ting the influence of chelating agents on the solubility of potentially hazardous heavy metals in soils. The effective- ness of eleven chelating agents for Cd++ in calcareous soils would be in the order: DTPA>CDTA, EDTA>HEDTA, EGTA>NTA>P207, P3010, CIT>OX>EDDHA (diethylenetriaminepentaacetic acid, cyclohexanediaminetetraacetic acid, ethylenediaminetetraace- tic acid, hydroxyethylethylenediaminetriacetic acid, ethyl- eneglycol-bis (2-aminoethylether) tetraacetic acid, nitrolo- triacetic acid, perphosphoric acid, triphosphoric acid, citric acid, oxalic acid, ethylenediamine di-gfhydroxyphenyl- acetic acid, reSpectively). Cadmium chelates such as Cd- DTPA (at high pH) or Cd-EGTA (at low pH) would be effective in increasing Cd solubility. DTPA (0.005 E) was used as an effective soil extractant for extraction of Cd from Rubicon sand and a Morley clay loam (Traynor, 1974). Role of Cadmium in Plants Cadmium is not considered an essential element for plant growth. Studies of plants grown on soils containing exces- sive amounts of Cd indicate that Cd is absorbed very readily. Haghiri (1973a) demonstrated that foliar-applied Cd was readily translocated into various parts of soybeans, however, uptake of Cd via the root system was significantly higher. Cadmium in various parts of the soybean plant decreased in the fol— lowing order: stem>leaves>pods>beans. John, Chuah, and VanLaernover (1972) grew oats on a soil contaminated with Cd deriving from a battery smelter in British Columbia. They reported very high Cd accumulations in the roots, but much smaller amounts of Cd in the shoots. John (1973) studied Cd uptake by eight food crOps as in- fluenced by various soil levels of Cd. He found that cer- tain crOps accumulate excessive amounts of Cd from soil treated with Cd from inorganic sources. Plant species vary greatly in their ability to accumulate Cd from both soil and nutrient culture solutions (Haghiri, 1973b; Yamagata and Shigematsu, 1970; Turner, 1973; Page, Bingham, and Nelson, 1972). Bingham et a1. (1973) grew corn, wheat, rice, field beans, soybean, cabbage, spinach, turnip, radish, tobacco, tomato, and squash, to commercial harvest stage using a soil pretreated with a municipal sludge (1%) containing variable amounts of CdSO4. Sensitive plants such as soybean, spinach, and field beans were injured by soil additions as low as 10 to 20 mg Cd per kg of soil. Cabbage, tomato, and rice tol- erated 400 to 600 mg Cd per kg soil. Preliminary work by Allaway (1968) indicated that plant growth depression due to Cd toxicity tended to occur after plants had accumulated approximately 3 ppm of this metal. Normal concentrations of Cd in plants were reported to fall in a range of 0.2 to 0.8 ug/g of dry plant material. Fulkerson and Goeller (1973) report that Cd may replace Zn as a cofactor and thereby cause many Zn-related enzymes to be non-functional. Symptoms of Cd poisoning may mimic a Zn deficiency. Traynor (1974) reported Cd toxicity in corn causing a severe growth retardation. John, VanLaernover, and Chuah (1972) in a study of factors affecting plant uptake and phytotoxicity of Cd added to soils, reported reduced yields of radishes showing chlorosis by soil application of 100 ppm Cd. He correlated Cd uptake with a variety of soil varia- bles. The ability of soils to absorb Cd was inversely pro- portional to Cd uptake. The same relationship applied to Cd absorption in high soils. Cd was more available to plants on acid soils. Lagerwerff (1971) found that increasing soil pH by liming somewhat supressed plant Cd uptake. Bremer and Baker (1973) conducted greenhouse experiments on a soil known to contain excessive levels of soil Zn and Cd. Treatments of CaCO3 and MgCO3 which increased soil pH gave better yields and somewhat suppressed plant Cd concentration. Lagerwerff and Biersdorff (1972) studied the interaction of Zn with uptake and translocation of Cd. Cadmium was added to a complete nutrient solution at 2, 20, and 100 ppb and factorially combined with 20, 100, and 400 ppb Zn. The two largest levels of Cd and Zn suppressed the uptake of Cd into the roots and leaves. However, at the highest con- centration of Cd and Zn, there was an increase in Cd uptake. Zinc may have been somewhat toxic at the 400 ppb level. Haghiri (1974) studied the effects of several soil fac- tors upon Cd uptake by plants. Cadmium concentration in oat shoots was decreased by increasing the cation exchange capacity (CEC) of the soil. Except for its CEC effect, organic matter did not influence Cd uptake in oat shoots. These results indicate the retaining power of organic matter for Cd may be predominantly through its CEC property rather than its chelating ability. Cadmium concentration in oat shoots was increased with increasing soil temperature. Chromium in Soil Chromium is widely distributed in soil, water, and bio- logical materials (Pratt, 1966). Concentrations of Cr commonly found in soils range from 5 to 3000 ug/g of soil, with an average of 100 ug/g soil (Allaway, 1968). Soils derived from ultra-basic or serpentine rocks, called serpen- tine soils, may have concentrations of Cr up to several per- cent (Pratt, 1966). Chromium is found in sewage sludges in varying amounts, depending upon location or source of the sludges (Peterson, Lue-Hing, and Zenz, 1973). The most stable oxidation state of Cr is the trivalent state, although Cr can occur in each of the oxidation states from -2 to +6. In the trivalent state, Cr has a strong ten- dency to form coordination compounds, complexes, and chelates (Mertz, 1969). Organic matter adsorption reactions with Cr may be im- portant in controlling available Cr in soil solution. Stevenson and Ardakani (1972) in a review on organic matter reactions involving micronutrients in soils, indicated that humic and fulvic acids can bind metal ions through both elec- trostatic forces (attraction of a positively charged metal ion to an ionized COOH group) and by electron pair sharing (formation of covalent linkage). Fulvic acids were found to form at least four types of chelate with Cr (Stevenson and Ardakani, 1972). Sorption and desorption of heavy metals by hydrous oxides of Fe and Mn may be important in controlling their availability. Jenne (1968) proposed that the hydrous oxides of Mn and Fe, which are nearly ubiquitous in clays, soils, and sediments, are principle agents in the fixation of heavy metals in soils and fresh water sediments. Results of an experiment conducted by Tiller et a1. (1963) indicate that fixation of heavy metals is related to the presence of adequate amounts of hydrous Fe and Mn oxides in the soil. Role of Chromium in Plants Mertz (1969) has reviewed literature on the occur- rence and function of Cr and has noted a number of beneficial effects upon plants and animals. However, specific func- tions of Cr in plants have not been determined, and existing knowledge of its role in vegetation is far from complete. Pratt (1966) indicated some of the beneficial effects of added Cr salts may have resulted from response to elements added with Cr, or to indirect effects. Tiffin (1972) found three anionic Cr complexes in extracts of manuka tea-tree. The xylem sap contained only Cr204-2 ions. Many researchers have studied toxic effects of Cr upon plants grown in both nutrient solutions and in the soil. Hunter and Vergnano (1953) found that the growth of oat plants was 32, 30, 25, 22, 19 and 13 cm, respectively, with 0, 5, 10, 15, 25 and 50 ppm of Cr as potassium chromate added to nutrient solutions. At 5 and 10 ppm, the effect was one of chlorosis. At 15, 25, and 50 ppm, specific symptoms of Cr toxicity appeared: stunting, with narrow, brownish- red leaves containing small necrotic areas and poorly developed roots. 10 Hunter and Vergnano (1953) were of the Opinion that the principle accumulation and toxic effect of Cr occurred in the roots of oat plants. Soane and Saunder (1959) reported that the Cr content of tobacco roots were 20 times the con- tent of the leaves of plants showing Cr toxicity. The leaves of the plants showing Cr toxicity had only slightly higher Cr content than leaves from healthy plants. Specific Cr toxicity symptoms for corn plants were reported by Soane and Saunder (1959). The toxicity range for Cr in corn leaves ranged from 4 to 8 ppm. The plants were severely stunted, while the leaves had a tendency to roll around the shoot. The leaves were purple-green and narrow, with intense purple color on the lower 2 inches of the lower blades. CrOpper (1967) reported Cr toxicity symptoms of corn similar to those reported by Soane and Saunder (1959). In an experiment in which corn was grown on a silt loam and a sandy soil containing sewage sludge with increasing amounts of Cr, CrOpper (1967) found decreased Fe, P, and Zn uptake at the highest rate of applied Cr. Manganese content was increased twice over the control. The plant Cr concentra- tion was lower on the silt loam soil as compared to the sandy soil. This may be due to the increased cation exchange ca- pacity or organic matter in the silt loam soil complexing Cr and subsequently making it less available to the plant. Schueneman and Ellis (1973) reported that plant response to added soil Cr varied with organic matter in the soils 11 studied. Plant growth was stimulated by application of 50 ppm +3 Cr on a soil containing high organic matter while the 50 ppm rate of Cr+3 on a soil low in organic matter decreased plant growth. Schimp et a1. (1957) and Prince (1957a, 1957b) report normal concentrations of Cr in corn tissue as follows: leaves of young corn plants ranged from 0.74 to 2.07 ppm Cr. Leaves at tasseling stage ranged from 0.69 to 1.22 ppm Cr. Leaves of mature plants ranged from 0.44 to 0.80 ppm Cr. Stalks of mature plants contain an average of 0.22 ppm Cr. Nickel in Soil Vanselow (1966) states that soils normally contain from 5 to 500 ppm of Ni, with an average of 100 ppm. Soils derived from sandstone, limestones, or acid igneous rocks generally contain less than 50 ppm Ni, while those soils derived from igneous rocks may contain from 5 to 500 ppm Ni. In a few areas, soils derived from unltrabasic igneous rocks could con- tain as much as 2000 ppm of total Ni (Hodgson et al., 1966). Exchangeable Ni, as determined by l N NH4OAc rather than total Ni in soils, appears to be closely correlated with the availability of Ni to plants (Soane and Saunder, 1959). Traynor (1974) has noted that Ni occurs in nature mainly in combination with As, At, and 8. Only NI+2 occurs in the ordinary chemistry of the element. Results of research by Schnitzer and Skinner (1966, 1967) indicated the following order of stabilities of 12 complexes found between a soil fulvic acid and nine divalent cations: Cu>Fe>Ni>Pb>Co>Ca>Zn>Mn>Mg at pH 3.5. When the pH was raised to pH 5.0, the order was changed to: Cu>Pb>Fe> Ni>Mn>Co>Ca>Zn>Mg. Ellis and.Knezek (1972) have noted that organic complex formation with metals through chelation or sequestration is an important bonding mechanism in soils. Stability diagrams for chelates of Ni++ have been pre- sented by Norvell (1972) to illustrate one method of esti- mating the influence of chelating agents on the solubility of potentially hazardous heavy metals in soils. The effec- tiveness of chelating agents as chelates for Ni+2 in calcar- eous soils would be in order: DTPA, HEDTA, EDTA>CDTA>NTA> EDDHA>CIT>OX, EGTA, P3010. Clearly, DTPA, HEDTA, EDTA, and CDTA could most effectively increase the solubility of Ni+2 in soils. Traynor (1974) using Langmuir adsorption data, has indi- cated that much of the Ni added to soil was inactivated through an adsorption mechanism. Crooke (1956) showed that toxic effects of serpentine soils high in Ni can be greatly alleviated by liming the soil, resulting in reduced availability of Ni. Massey (1972) conducted a study of soil contaminated from mining operations in Kentucky. Of the 3 metals studied, Cu, Zn, and Ni, nickel is the most likely to remain in solution in toxic amounts after the soil pH is raised by liming. Approximately 4.3, 2.5, and 1.4 ppm Ni was left in 13 solution at pH 4.5, 5.5, and 6.5, respectively. Traynor (1974) has noted that hydrous oxides of Mn and Fe which are nearly ubiquitous in clays, soils and sediment, may exert the principal control on the fixation of Co, Ni, Cu and Zn. Role of Nickel in Plants Nickel is not considered as essential element for plants. EXperiments by Tiffin (1972) have revealed nega- tively charged Ni in xylem exudates of tomato, cucumber, corn, carrot, and peanut. Schroeder et a1. (1967) stated that Ni behaves similar to an essential trace element. Traynor (1974) indicated Ni activates several enzymes including arginase, carboxylase, acetyl coenzyme A synthetase, and trypsin. It was also noted that Ni inhibits acid phosphatase under certain conditions and catalyzes the enzymatic decar- boxylation of oxalic acid. CrOpper (1967) investigated the effect of added soil Ni to a sludge-amended soil. He found that Ni accentuated a Ca deficiency symptom observed in the control. Potassium, Mn, and Zn uptake was increased by increasing soil Ni levels. Crooke and Inkson (1955) noted that the concentration of Ca in dry matter of the plant tOps was more than doubled in the presence of Ni toxic tissue. Vanselow (1966) and Crooke and Knight (1955) have des- cribed symptoms of oat plants affected by Ni toxicity as a deficiency of plant metabolism causing white necrotic 14 striping of the leaves accompanied by an induced Fe deficiency chlorosis. Crooke, Hunter and Vergnano (1954) studied the relation- ship between Ni toxicity and Fe supply and found that an in- crease in the Fe level in the nutrient solution produced a reduction in Ni toxicity symptoms and Ni content in oats. In further experiments Crooke and Knight (1955) and Crooke (1955), using autoradiographs of leaves and plants supplied with radioactive Fe, showed that necrotic areas in the leaf matched areas of low Fe content. They suggested there was a migration of nutrients out of the dying tissue. These ex- periments also indicated that a high Fe supply reduced the severity of necrosis no more than could be accounted for by the reduction in Ni content. An experiment conducted by Hunter and Vergnano (1952) indicated a wide range of crOps vary considerably in their susceptibility of Ni toxicity. Many crOps were tested and their resistance to toxicity of Ni from greatest to least are listed in the following order: barley>wheatp ryegrass, beans>oats, clover, potatoes>turnips, swedes, cabbage, kale> beets. Allaway (1968) indicated that normal levels of Ni in plant tissue were about 1 ug/g plant tissue while a toxic level would be anything greater than 50 ug/g plant tissue. 15 Zinc in Soil KrauskOpf (1972) reports concentrations of Zn in igneous rocks of basaltic origin and granite origin as 100 ppm and 40 ppm, respectively. Among ordinary sedimentary rocks the greatest concentrations of Zn are found in shales. The chemistry of Zn shows only a single valence state in natural materials. A weathering of Zn minerals gives Zn+2 in solution. The total Zn content of soils varies from 10 to 300 ppm (Allaway, 1968). In most soils, more Zn is found in the surface that in subsurface horizons (Chapman, 1966). Bould (1963) stated that Zn is adsorbed as a divalent cation on clays or complexed by organic matter after release from the minerals. Bingham, Page,and Sims, (1964) reported that montmorillonite is capable of adsorbing Zn or Cu beyond its cation exchange capacity, particularly at near-neutral or alkaline pH levels. This was explained as a result of precipitation of Zn as Zn(OH)2. Jurinak and Thorne (1955) stated that chemical complexes, strong clay adsorption com- plexes and Zn hydroxide were formed in soils. Ellis and Knezek (1972) and Stevenson and Ardakani (1972) have reviewed literature related to relationships between Zn and soil organic matter and prOposed mechanisms by which Zn is adsorbed by organic matter. Soil organic matter forms very stable complexes with both Zn and Cu. Himes and Barber (1957) removed organic matter from soil and destroyed the chelating ability of the carboxyl and phenolic 16 functional groups. Randhawa and Broadbent (1965) showed that the complexing ability of humic acid increased rapidly with an increasing hydroxyl ion concentration up to pH 8.5. Hodgson, Lindsay and Trierweiler (1966) found that only a small proportion of total Zn in the soil is complexed by organic matter. However, 28 to 99 percent of the Zn in soil solution is complexed by organic matter. Norvell (1972) calculated ratios of chelated Zn to Zn+2 for 11 chelating agents. In the pH range of calcareous 2 I O I + I 50113 their effectiveness as Zn chelates are in the order: DTPA>CDTA,HEDTA, EDTA, NTA>EGTA>CIT, EDDHA, P3010,P207, OX. The degree of chelation of Zn+2 by EGTA, CIT, EDDHA, P3010, 2 P O and OX is similar to that for natural complexes of Zn+ 2 7' in soil solution. Role of Zinc in Plants Chapman (1966) noted that the essentiality of Zn for plant life was not fully accepted until the early 1930's. Bonner and Varner (1965) indicated a concentration of approx- imately 20 ppm Zn in plant tops appeared to be Optimal for normal plant growth and metabolism. Allaway (1968) reports that a normal concentration of Zn found in plants range from 15 to 200 ug/g plant tissue while a toxic range may be greater than 200 ug/g plant tissue. Melton, Ellis and Doll (1970) conducted an experiment in which 3 levels of Zn were added to 20 Michigan soils and pea beans were grown. Pea bean growth was reduced by both 17 Zn deficiency (below 20 ppm) and toxicity (above 50 ppm Zn in plant tissue). Chapman (1966) found levels of Zn in plant dry matter ranging from 20 ppm to 10,200 ppm. Clearly, Zn may readily accumulate in plants in considerable amounts. The primary role of Zn in plant growth is that of a catalyst. Prince, Clark and Funkhouser (1972) noted that Zn is an essential component of a variety of dehydrogenases, proteinases, and peptidases. Zinc may be involved in chloro- phyll synthesis and rate of tranSpiration (Schutte, 1964). Visual deficiency symptoms in plant tOps are inter- veinal chlorosis, necrosis of lower leaves, and shortening of internodes (Melton, 1968). Zinc toxicity symptoms for corn was described by CrOpper (1967) as stunting, lower yields, and bright red older leaves. Chapman, Liebig and Vanselow (1940) produced Fe chlorosis in citrus grown on sand and solution cultures containing excessive Zn. Iron chlor- osis was produced in oats grown in sand culture with added increments of Zn up to 100 ppm. At 25 ppm of added Zn, the chlorosis was faint and the leaves contained 1,700 ppm Zn. When 100 ppm was added, the chlorosis became more severe with the leaves accumulating 7,500 ppm Zn (Hunter and Vergnano, 1953). King and Morris (1972) reported a decrease in soil pH with sewage sludge treatments with a resultant increase in exchangeable and water-soluble Mn and exchangeable Zn in the soil. Terman, Soileau and Allen (1973) conducted an 18 experiment to study the possible toxic effects of Zn buildup in an acid soil from heavy application of a Johnson City compost. Concentrations of Zn in plant teps was increased. However, liming the soil reduced plant Zn concentration and toxicity. Bremer and Baker (1973), Chaney (1973), and Melton et a1. (1970) have observed that plant Zn uptake is dependent upon soil pH and texture. Rogers and Wu (1948) concluded that liming reduced Zn uptake by increasing soil pH. Bingham and Garber (1960) related soil type to P-induced Zn defic- iency. A reduction in both P and Zn uptake was found in kidney beans, corn, and tomatoes when P was applied to limed soils (Burlson, Dacus and Gerard, 1961; Ward et al., 1963). Heavy P application generally induced greater Zn deficiency on soils above pH 7.0 (Melton et a1. 1970). EXPERIMENTAL METHODS Greenhouse Studies The effect of heavy metal contaminants on growth and mineral composition of corn was evaluated in the greenhouse using a Houghton muck soil supplied with increasing additions of Cd, Cr, Ni and Zn. Rates of application were based, in part, on existing information regarding toxicities of these metals and, in part, on visual observations of plant response in a pilot study. Seven levels of addition were used. For Cd and Cr, these were 0.05, 0.1, 0.25, 0.5, 0.75, 1.0 and 2.0 meg/100 9. Additions of Ni and Zn were 0.1, 0.2, 0.5, 1.0, 3.0, 6.0 and 9.0 meg/100 g. The metals were supplied as the chloride salts and mixed thoroughly with the soil two weeks prior to planting. A control treatment did not receive any of these metals but was otherwise handled similarly. Uniform additions of Mn, N, P and K were incorporated with each experimental lot of soil. The Mn addition was 20 ppm as manganese sulfate. Nitrogen, P and K were added as recommended for corn by the Michigan C00perative Extension Soil Testing Lab (N-P-K = 150-100-50 kg/ha). Prior to these amendments, the Houghton muck had been passed through a 6-mesh stainless steel screen and mixed l9 20 thoroughly. After treatment, the soil was diSpensed in 3- quart plastic pails which were used as growth containers _(1.4 kg per container). Quadruplicate containers were set up for each of the 29 treatments and were arranged as rando- mized blocks in the greenhouse. On April 25, 1973, ten corn seeds (variety Michigan 500) were evenly spaced three-fourths inch below the soil surface and 1.5 inches from the edge of each container. All con- tainers were watered with 100 m1 of deionized water after planting. After seed germination, deionized water was added daily as needed, each container being brought up to a con- stant weight twice weekly. Three hours of supplemental lighting was used daily. Plants were thinned to six per container two weeks after germination. Plastic stakes were inserted into the pots to support the plants. Plant growth differences were recorded with photographs. On May 30, 1973, plant tops were cut with stainless steel razor blades and dried at 60°C in paper bags. Dry weights were recorded. A stainless steel Wiley mill was used to grind the plant samples to pass a 20 mesh screen. Plant Analytical Methods One gram portions of the dry ground plant samples were wet ashed with nitric and perchloric acids in 100 ml Kjeldahl flasks. The reduced volume (5 ml) was brought up to 100 ml with deionized water and Cd, Cr, Cu, Fe, Mn, Ni, and Zn 21 content of the digest was analyzed with a Perkin-Elmer 303 atomic absorption spectrophotometer. Calcium, K, Mg, and P were analyzed by the International Minerals and Chemical Corporation plant analysis laboratory using emission spectrographic analysis procedures. Soil Analytical Methods Surface (0 to 10 cm) soil was collected from the Michigan State University Muck Experimental Farm. A uniform sample was prepared by sieving the soil through a 6-mesh stainless steel screen and mixing thoroughly. Soil moisture content (65%) was determined by the Michigan C00perative Extension Soil Testing Lab. This was the normal field moisture content and was maintained from time of soil collection throughout the experimental period. A chemical analysis of this soil as adapted from the dissertation of Brown (1949) and Timm (1952) is given in Table 1. Soil pH Soil pH was determined by mixing 5 grams of soil with 10 ml of water (1:2 ratio). The mixture was remixed again after 15 minutes and the pH of the suspension read using a Beckman Zeromatic glass electrode pH meter. The soil pH was 6.7. Soil pH was measured on each treatment after crOpping and was found to be insignificantly changed with metal addition. 22 Table 1. Chemical prOperties of a Houghton muck soil from the Michigan State University Experimental Muck Farm. PH 6.7 Organic matter, % 82.6 Ash, % 17.4 Exchangeable Hydrogen, meg/100 g 45.1 Total Exchange Capacity, meg/100 9 166.5 Exchangeable Cations, meg/100 g 121.4 Base Saturation, % 72.9 Total N, % 3.3 P, % 0.12 Ca, % 2.5 Mg, % 0.27 Fe, % 1.3 Cu, % 0.0011 23 Extractable Cadmium, Chromium, Copper, Iron, Manganese, Nickel and Zinc Soil metals were extracted using three different pro- cedures listed in Table 2. The extractants were used to find the most effective method of determining available soil metals. The metal content in the extract was analyzed by using a Perkin-Elmer Model 303 atomic absorption spectropho- tometer. Table 2. Soil extraction procedures. Extracting Soil-Solution Method of Extraction Time Solution Ratio Extraction (minutes) 0.1 N HCl 5:50 Shaking 30 1.0 N NH4OAC 5:50 Shaking 30 o . 005 g DTPA 10 : 4o Shaking 12 0a aMethod of Lindsay and Norvell (1969). Statistical Procedures All data were subjected to analysis of variance in accordance with a randomized block design. Facilities of Michigan State University Computer Center and STAT routines of the Michigan Agricultural Experiment Station were used. RESULTS AND DI SCUSSI ON Effect of Increasing Concentrations of Soil Applied Cadmium upon GrowtthYield, and Nutrient Composition of Corn Growth and color differences were observed in early stages of plant growth (emergence to 3 weeks). Delayed seedling emergence up to 48 hours compared to the control was caused by the higher rates of Cd (0.25 to 2.0 meg/100 9). Plants receiving the above rates of Cd were stunted and appeared to be somewhat chlorotic in comparison to the con- trol treatment (Plate 1). Yields of dry matter and plant chemical composition are given in Tables 3 and 4. Soil additions of Cd from 0.25 to 2.0 meg/100 9 reduced plant growth (0.69 g/plant to 0.28 g/ plant) significantly compared to the control (1.37 g/plant). Increases in Cd concentration from 16 to 136 ppm resulted from soil Cd additions of 0.05 to 2.0 meg/100 g, respectively (Figure 1). Increasing Cd rates reduced plant uptake of Cu, Fe, Mn, and Zn but plant concentration of Cu, Fe, and Zn were not significantly changed due to Cd treatments. These results indicate that uptake of Cu, Fe, and Zn was reduced in prOpor- tion to growth reduction due to Cd toxicity. Plant Mn con- centration significantly increased at the two highest rates of soil Cd. Addition of Cd to the soil may have displaced some Mn from complexed forms making this metal more available 24 25 Plate 1. Photograph showing growth of corn plants grown on Houghton muck after graded additions of cadmium. Figure 1. 27 Yields of dry matter and cadmium content of corn plants grown on Houghton muck after graded additions of cadmium. 28 (wand/6) 1H9l3M we 38.31.325.84 22230 3.8 N _ no Iain—<0 .52.... I #2933 >¢clll O N .ow (wdd) nouvamaowoo wnlwavo lNV'ld 29 .wcoflumofiammu e mo mmmuw>m on» we msam> comma .muHEHH cofiuomump 30Hwn mum3 mam>wa meoflz can Edflsounum mm .m.z m.H H mm .m.z m .m.z m.h ma ma.o Amo.ov omq ma mm m.m m Hv hva r em mm mma mm. «NHH o.~ hm NHH ~.N m me mom v oa ma on em. mom o.H ma mm o.a 5 mm nma v ma m hm Hm. omv mb.o hm mm N.N > me mma h on ma vv mm. Hmm m.o Nv mm m.v 0 mm oma ma ma hm mm mm. ova mm.o mm mm m.¢ v OHH «m ma ma hm MN mH.H mm H.o ooa mm NH 5 ram mNH mm ma mm ma mn.H mm mo.o ooa on oa n «ma HvH ma va 0 o hm.a o o ucmHm\ms Ema unmam\ms Ema ucmHQ\ms Ema unmaa\ms Sam ucmam\ms Ema uanQ\m Ema m ooa\ome mxwums 0:00 wxmums ocoo wxmum: ocoo mxmumd ucoo mxmums ocoo pamflw cofluappm am a: mm 50 co ESHEUMU n.m.EdfiEpmo mo mcofiuwppm pmomuo kumm x036 coucosom co c3oum mucmHm cuoo mo acoucoo Hmume pom uwuums amp mo moamflw .m manme 30 Table 4. Yields of dry matter and nutrient content of corn plants grown on Houghton muck after graded additions of cadmium.a Cadmium Nutrient addition Yield P K Ca Mg meg/100 9 ppm g/plant ------------ % ----------- 0 O 1.37 0.21 3.72 0.69 0.69 0.05 28 1.75 0.25 6.24 0.45 0.36 0.10 56 1.19 0.26 7.13 0.59 0.39 0.25 140 0.69 0.25 7.60 0.66 0.40 0.50 281 0.33 0.25 7.71 0.74 0.42 0.75 420 0.21 0.29 6.33 0.80 0.42 1.00 562 0.24 0.29 7.37 0.86 0.46 2.00 1124 0.28 0.26 7.15 1.29 0.45 LSD (0.05) 0.19 0.03 0.96 0.09 0.04 aEach value represents the average of 4 replications. 31 to the plant. Cadmium additions significantly increased the P and K content of the plants but Mg content was signifi- cantly lower in comparison to the control. Calcium content of plants was increased by rates of Cd ranging form 0.75 to 2.0 meq/100 g. Apparently the plants continued to take up P, K, and Ca even when they ceased growing. Inflpence of Increasing Soil Cadmium Concentrations upon Soil Extractable Metal Concentrations Soil extraction data for Cd (Table 5) reveal that 0.1 N HCl and 0.005 M DTPA removed nearly equal amounts of Cd. Quantities of Cd extracted with 0.1 N HCl and 0.005 M_DTPA ranged from 19 to 871 ppm and 28 to 752 ppm, respectively. Soil extraction with l N NH4OAc removed only 20 to 30 percent as much Cd as other extractants. All extractants removed in— creasing amounts of Cd corresponding to the graded additions of soil Cd. The 0.1 g HCl, 0.005 g DTPA, and 1 Pl NH4OAc extracts removed 77, 67, and 19 percent reSpectively of the added Cd at the 2.0 meg/100 g rate. These data indicate Cd is not fixed strongly by soil particles resulting in avail- ability to plants. Iron and Cu in the 0.1 N HCl extract were significantly increased by Cd additions in comparison to the control but the 0.005 M DTPA extractable Fe was significantly lower than the control at the high rates of Cd. Manganese and Zn were not significantly influenced by in- creasing Cd rates. 32 m.o m.em m.m .m.z m.o ~.o 5.4H H.4H H.mH Amo.oc own m.H n.wm~ o.mm nu- m.m m.H m.ma~ «.mmh n.oem «NHH oo.~ m.~ N.~N~ e.~v -uu o.v m.H H.m~H 4.4mm o.mmv mom oo.H o.m e.mmm m.em nu: H.v 5.3 m.vm n.mmm m.q~m owe me.o o.~ m.mm~ v.em nun v.4 o.H m.mm o.mom m.oma Ham om.o m.a m.em~ H.Hm nu- m.v o.H ~.v~ m.mm m.aoa oqa mm.o e.H ~.mmm m.m~ nun ~.m m.o H.m ~.mv e.Hv mm oa.o o.H ~.~mm o.m~ unu G.v m.o m.m n.5m H.ma mm mo.o 0.3 m.m~m m.v~ nu- ~.v m.o nu- nu: nun o o IIIIIIIIII IIIIIIIIIIIIIIIII:Illllnllnllllu Ema IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII Ema m ooa\om5 oKOvmz laden Iaom oncemz naaeo Iaom unoamz lameo Iaom cofluaocm 2 H z moowp 2 five 2 H z moo.o z ebb 2 H z moo.o z Hnb asflevmo mm so go mcoHDDHOm mcwuomuuxw 0cm mamumz b.m.cuoo nuw3 mcaamouo xn pmonHOM EsHEpmo mo mcofluflopm pwpmum umuwm x028 counmsom cfl mamumfi pwuomamm mo Hofl>mcmn cofluomuuxm .m wands .muflefia cofluomump 3000b mum3 maw>ma meowz 0:0 850800209 .mcowumowammu 0 mo mmmum>0 on» mucmmmummn msam> nommm 33 .0.z .0.2 .0.2 0.0 .m.z .0.z 100.00 003 0.0 0.0 0.03 0.0 0.3 0.00 0033 00.0 3.0 0.33 0.0 0.0 0.0 0.00 000 00.3 0.3 0.0 0.0 0.0 0.0 0.00 000 00.0 0.0 0.0 0.0 0.0 0.3 0.00 300 00.0 0.0 0.0 0.03 3.0 0.3 0.00 003 00.0 0.3 0.0 0.03 0.0 0.3 3.00 00 03.0 0.0 0.0 0.0 0.0 0.3 3.00 00 00.0 0.0 0.0 0.03 3.0 3.3 0.30 0 0 IIIIIIIIII IIIII IIIIIIIIIII Ema IIIIIIIIIIIIIIIIIIIIIIIII Ema m ooH\me oMO0mz Imago .I3om 0M00mz lameo I300 00000000 2.0, 2 000.0 z 000 z 0, 2 000.0 2 3.0 0032000 cN :2 mcoflu9000 mcfiuomuuxm 0:0 mamumz Aposswucoov m manna 34 Effect of IncreasingpConcentrations of Soil Applied Chromium ppon Plant Growth, Yield, and Nutrient Composition of Corn Growth differences due to Cr treatments were signifi- cantly different from the control (Plate 2). Plant dry weight yields increased significantly in all Cr treatments when compared to the control. Dry weights ranging from 1.37 g/plant in the control to 2.71 g/plant at the 1.0 meq/100 9 Cr rate indicate a doubling of the dry weight yield due to the Cr treatment. Visual growth differences between the con— trol plants and the plants grown on the Cr amended soil other than plant size were not evident. A chemical analysis of plant material is presented in Tables 6 and 7. Detectable levels of Cr were not translocated to the plant tOps. Con- centrations of Cr, Fe, and Zn in plant tissue due to Cr treatment were not significantly different from the control. Plant Mn uptake was significantly increased due to increasing Cr rates (Figure 2). Manganese uptake increased from 9 ug/ plant in the control to 49 ug/plant with the 2.0 meg/100 g rate of Cr. The increase in plant growth probably resulted from a displacement of Mn from the soil complex by the added Cr with a subsequent increase in available Mn for plant uptake. Chromium treatments increased plant K concentration while decreasing Mg and Ca concentrations significantly. Phosphorus content in plant tops was increased with Cr rates up to 0.25 meg/100 9 but higher Cr rates significantly decreased the plant P concentration. 35 Plate 2. Photograph showing growth of corn plants grown on Houghton muck after graded additions of chromium. 37 Figure 2. Yields of dry matter and manganese uptake of corn plants grown on Houghton muck after graded additions of chromium. 38 (mud/6) 1H9l3M A30 1000.085 20.0300 20.20000 _ 0.0 4.0m d 9.5:: a! II .5553 >mo Ill o. (wand/5'") smudn asauvowvw 39 .ms00umoflammu 0 mo mmmum>m may mucmmmnmmu msam> comma .mabmuomumplcoc 0003 mam>ma meOHZ 0cm .ESHEOHSU .Edwfiomum .m.z .m.z m o.~ Hoa .m.z ma .m.z mm. “mo.ov own mma mm m0 om «mm 000 N0 0H H0.~ 00m o.m mma mm mm ma Hmm H0 00 ma Hh.~ mud 0.0 ova mo 0m oa 00m mNH Hm ma mm.m OMH m0. mma mm on 0 00m mma mm ma o~.~ 0m om. 0N0 0m om m mmm HNH m0 om mm.~ m0 mm. med MB on 0 Hum mma av ma 0N.m 00 03. Ana mm ma 0 0mm mma mm 00 mo.~ 0 mo. mm 00 0 0 003 000 ma 0H hm.a o o uc0HA\ms Ema unmaa\vs Ema unman\ms 8mm unmaokos Ema mucmam\m 5mm 0 ooa\ome mxmumd ocoo mxmumw ocoo mxmums ocoo mxmumw ocoo Gamay cowuwpom s0 :2 mm so Bowsoucu n.0.Esfleouno mo mcofiuwppm nmomuo ngmm x098 sounmsom co csoum mucmam suoo mo ucwucoo Hmume 0:0 Hmuuma hup mo moamww .m manna 40 Table 7. Yields of dry matter and nutrient content of corn plants grown on Houghton muck after graded additions of chromium.a Chromium _Nutrient addition Yield P K Ca Mg» meg/100 g ppm g/plant ------------ % ----------- 0 0 1.37 .21 3.72 .69 .69 0.05 9 2.06 .24 5.98 .45 .39 0.10 17 2.27 .26 5.62 .44 .37 0.25 43 2.23 .24 5.70 .44 .38 0.50 87 2.20 .19 5.39 .45 .38 0.75 130 2.32 .19 5.43 .46 .38 1.0 173 2.70 .19 4.58 .48 .36 2.0 347 2.41 .17 5.24 .53 .38 LSD (0.05) .39 .02 1.10 .05 .04 aEach value represents the average of 4 replications. 41 Influence of Increasing Soil Chromium Concentrations upon Soil Extractable Metal Concentrations Results of metal extraction of soils receiving graded additions of Cr are given in Table 8. Two of the extracting solutions (0.005 M_DTPA and 1 N NH4OAc) did not remove any detectable Cr from the soil. The 0.1 N HCl extracting so— lution removed only small amounts of Cr ranging from 0.1 to 2.3 ppm. Soil Cr additions significantly decreased the 0.1 N HCl and 0.005 M DTPA extractable Fe below the control treat- ment. These data indicate the Cr is very tightly bound by the soil complex, possibly by soil organic matter or by com- plexing with soil Fe. Extractable Cu, Mn, and Zn were not significantly affected by graded Cr additions. Effect of Increasing Concentrations of Soil Applied Nickel ppon Plant Growth, Yield, and Nutrient Composition of Corn Plants grown on soil receiving rates of Ni from 0.1 to 3.0 meg/100 9 increased in dry weight while rates of Ni above 3.0 meg/100 g caused a significant dry weight reduction. Foliage color of plants growing on soil receiving rates up to 3.0 meq/100 g was similar to the control but higher rates of Ni caused interveinal chlorosis (6.0 meq/100 g) and plant death (9.0 meg/100 g). Plants grown on soil treated with 9.0 meg/100 g became very light in color within 3 weeks and turning brown at 5 weeks (Plate 3). A chemical analysis of the plant tissue is given in Tables 9 and 10. Nickel concen- tration in plant tops was increased significantly correspon- ding to soil Ni additions (Figure 3). The Ni content in plant tissue ranged from 6 to 508 ppm. Nickel became toxic 42 Plate 3. Photograph showing growth of corn plants grown on Houghton muck after graded additions of nickel. 43 44 Figure 3. Yields of dry matter and nickel content of corn plants grown on Houghton muck after graded additions of nickel. 45 (wand/5) lH9l3M A30 300.035 20.0500 3.00.0.2 .__00 j (de) Nouvamaowoo 13mm lNV‘ld 3.3.0.2 0230' . oom / 000.03 000 .i u / 00¢ O O (D 46 .0.2 0.00 0.0 .m.z 3.0 0.0 “00.00 003 0.3 0.000 0.03 uu- 0.0 0.0 nu- nun 0.0 000 00.0 0.3 0.000 3.03 nun 0.0 0.0 nun nu- 0.3 003 00.3 0.3 0.000 0.03 uu- 0.0 0.0 nun .:u 0.3 003 00.0 0.3 0.000 0.03 n-- 0.0 0.0 nun nun 0.0 00 00.0 0.3 0.000 0.03 nu- 0.0 0.0 nu- nu- 0.0 00 00.0 0.3 0.000 0.03 In- 0.0 0.0 In: nun 3.0 03 03.0 0.3 0.300 3.03 uu- 0.0 0.0 nun unu nun 0 00.0 0.3 0.030 0.00 nun 0.0 0.0 nu: nu- nun 0 0 IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII Ema uIIuIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIInI Ema m ooa\o0E omO0mz 14000 I300 000002 14000 I300 000002 I<0eo I30: :O303000 z 0 2 000.0 z 040 z 3 2 000.0 2 3M0 z 0 2 000.0 2 awn 203eo000 0m so 00 000005300 mcfluo0uux0 000 030002 n.0.cuoo £003 mcflmmouo >0 00303300 EdHEouno no 000303000 000000 u0uw0 xUDE 0002050: :0 030005 00000300 mo HOH>0£0Q coHuomuuxm .m 0300B 47 .000800 000000000 30000 0003 000>0H 300002 000 65050000 .000000000000 0 mo 00000>0 000 0000000000 0000> 000m0 .0.2 .0.2 .0.2 .0.2 .0.2 .0.2 200.00 000 3.3 3.03 0.0 0.0 0.3 0.00 0033 00.0 0.0 0.0 3.0 0.0 0.3 0.03 000 00.3. 3.3 0.0 3.0 0.0 0.3 3.00 000 00.0 0.3 0.33 0.0 0.0 0.3 0.30 300 00.0 0.0 0.03 0.0 0.0 0.3 0.00 003 00.0 3.3 0.33 0.0 0.0 0.3 0.00 00 03.0 0.0 0.0 0.03 -11 0.3 0.03 00 00.0 0.3 0.0 0.03 3.0 3.3 0.30 0 0 11111111 IIIIIIIII 111111111 Baa 1111111111111111111111111 Ema m boa\00§ owmqmz 10090 1300 000002 10090 1300 00303000 2 H z WW0.0 2 3.0 2.3 2.mm0.p 2.000 03020000 000005000100000000x0 0:0 000002 00050000000 0 00009 48 .m:0wum0flammu e no momm0>m 0:0 mu:0mmummu 05Hw> nommn manmuomumol:o: 0:03 mH0>0H Esflaouno 0:0 Edwfiomom om .w.z NH v ooa mm m m hN Ha mv. Amo.ov omq h vs N mN m Hm H Ha me mom mo.o avoN o.m mm we mN MN mHH mm «a NH NOH mm mH.H Hmha o.m mom mm 5v ma va moa Nv ma Nb vN No.m omm o.m mma Hm oN m vom ooa mv ma mm NH Ho.m mmN o.H NMH mm ma 0 NHN om mN NH HN m om.N hva m.o bma hm ma m mom vva mm ma ma w OH.N mm N.o Hoa bv ma m NnN VNH mm ma ma h hH.N mN H.o ooa ¢n m n «ma HVH ma vH III III hm.a o o 0:0Hm\ws Ema u:mam\os Ema u:mam\os Ema ucmam\ms Ema u:mHm\ms Ema u:mam\m Sam 0 ooa\vwe 0xmum: 0:00 mxmums 0:00 0xmumd 0:00 0xmum: 0:00 wxmum: 0:00 wamfiw :ofluflvcm :N :2 mm :0 Hz meofiz .m.H0x0fl: mo m:0fiuflonm vmwmum uwumm x055 :0050902 :0 :Boum mu:mHm :u00 m0 u:mu:00 H0008 0:0 uwuumfi huvnmo mvamflw .m 0HQMB 49 Table 10. Yields of dry matter and nutrient content of corn plants grown on Houghton muck after graded additions of nickel.a Nickel Nutrient addition Yield P K Ca Mg meg/100 9 ppm g/plant ------------ % ----------- O 0 1.37 .21 3.71 .69 .69 0.1 29 2.17 .23 5.62 .42 .34 0.2 59 2.10 .26 5.88 .42 .36 0.5 147 2.30 .24 5.13 .44 .38 1.0 293 3.01 .23 4.19 .45 .36 3.0 880 3.02 .25 3.96 .63 .42 6.0 1761 1.19 .19 5.25 1.35 .49 9.0 2641 0.09 .20 3.46 3.44 .80 LSD (0.05) .49 .02 .59 .17 .06 ¥ a Each value represents the average of 4 replications. 50 to the plants when the concentration in the plant was greater than 24 ppm as indicated by reduced plant dry weight and visual toxic symptoms. Increases in yield of plant dry weight at lower rates of Ni (0.1 to 3.0 meq/lOO g) was probably due to a displacement of adsorbed or complexed Mn and Cu with a subsequent increase in Mn and Cu uptake (Fig- ures 4 and 5). Plant uptake of Mn and Cu is significantly increased above the control with increasing soil Ni treat- ments up to 3.0 meq/lOO 9 but higher treatments reduced up- take of Mn and Cu. Plant Fe concentration was reduced sig- nificantly below the control with added Ni. Reduced plant Fe concentration may cause a more favorable Fe/Mn ratio in the plant resulting in increased Mn uptake. Plants which were slightly Mn deficient may have responded to this in- crease in Mn uptake by increased growth (plant dry weight). There was no significant difference in plant Zn concentration with increasing Ni rates. Plant concentration of P, K, and Mg were not significantly different from the control. The plant Ca concentration was significantly increased at the 6.0 and 9.0 meg/100 9 addition of Ni. Influence of Increasing Soil Nickel Concentrations upon Soil Extractable Metal Concentrations Results from the soil extractions (Table 11) indicate that 1 N NH4OAC removed only a small amount of the added Ni. The 0.1 N HCl removed between 36 and 102 percent as much Ni as did the 0.005 M DTPA solution. Each extracting solution removed increasing amounts of Ni corresponding to added soil 51 Figure 4. Yields of dry matter and copper uptake of corn plants grown on Houghton muck after graded additions of nickel. 52 (wold/6) 1H9|3M we 38:85 29:84 .55.: .__8 m m _ 9.30: :o bra—m3 :3 III o. (wold/6'") 3>lVldn HdeOO Figure 5. 53 Yields of dry matter and manganese uptake of corn plants grown on Houghton muck after graded additions of nickel. 54 (wand/5) 1H9|3M we 38:35 20:52 .96.: .__8 m _ mxchm: 5‘ I .2553 :3 III O (wold/5") amudn asauvsww on 55 N.o mN m.m m.o m.o v.HH «.mN m.o>a Amo.ov 0mg m.H Hm «.mv unn m.o ~.~ «.mvm ~.mmmH m.mmoa aqom o.m 5.: mm m.Hm nun v.a ~.H m.HvH m.mn~H o.vmm Hana o.m m.H Hm: m.va In: o.v n.o o.mm H.0Hn m.vmm omm o.m m.H Hmm H.ma nu- 0.4 0.0 m.m m.omm v.nmm mmm o.H o.H 5mm m.H~ nun n.v m.o m.m v.nm m.ov nva m.o m.H 5mm H.o~ an- 4.4 m.o In: m.mm n.ma mm «.0 m.H 5mm 0.0H nu- n.q m.o uuu n.5H 4.0 mm H.o m.H mam m.v~ nu: m.¢ m.o In: nun nun o o u: IIIIIII I IIIIII III IIIIIIIIIII uIIIIIIIIIII Ema IIIIuIIIIIIIIIIIIIIIIIIIIIIIIIIIIuIIIIIII Ema m ooa\va emcemz lame: Iaom omoamz Iamso Iaom awo4mz lame: Iaom coflufloom z a z moo.o z H.o 2 H z moo.o z Hwb‘ 2 H z moo.o z H.o meofiz 0m :0 Hz m:oHusH0m m:flu0muux0 ©:m macaw: b.m.:u00 :uflz m:ammouo an pmonHOM H0x0H: mo m:owuwcom pmpMHo umumm x056 :ounmsom ca mamume omuooamm mo u0a>mnon :ofluomuuxm .HH wanna 56 .mpwfiwa :ofiuomumo 30am: 0H03 maw>ma Edweouno 0:0 Esflecmon .m:0wumowamon v m0 mmmuo>m 0:» mu:0mmummn moam> nommm .m.z .m.z .m.z .m.z m.o m.m Amo.ov am: H.H m.m m.HH m.o v.o m.~m Hamm o.m m.o H.~H m.m N.o m.o m.mm fiend 0.0 H.H H.o o.HH ~.o H.H 6.0H omm o.m o.a H.~H m.m ~.o H.H o.oa mma o.H «.0 ~.m o.oa ~.o m.H m.¢~ was m.o H.H o.oa m.m ~.o m.H m.H~ mm ~.o n.o m.m 5.HH 0.0 ~.H m.ma mm H.c >.H o.m o.¢a H.o ~.H m.H~ o o -u-y------u----u ..... -un--- an: -uuuuuuuuuuuuuuuuuuuusuu an: m mbmxams unawaz I0 0:0 00:0000000 09H0> :00mn .0000000000|:0: 0:03 mH0>0H waoflz 0:0 .Esfleousu .55050000 m m om .m.z m .m.z vHH mov mv. Amo.ov om: mv om mom av: MN 0H mmmN mama Nq.H Nva o.m vm mN omm mm: mm ma hmmm mNmH mm.N Head 0.0 vm ma omN Noa 0v ma mmm mmm ow.N omm o.m 0H m HHN mma Hm ON mum mNN mm.H th o.H m 0 mm: HvH NN ha omH nva Nm.H med m.o n m moa HNH ma va mmH maa vo.H mo N.o o m Hma Hoa 0H NH maa mm hm.H mm H.o m n vma HvH ma va OOH vb hm.H o o 0:0Hm\m: Ema 0:0Hm\o: Ema 0:0Hm\ms Ema 0:0Hm\m: Ema 0:0HQ\o Sam 0 ooa\UOE 0x00md 0:00 0x000: 0:00 0x00ms 0:00 0x00m: 0:00 0HOH» 0:000:000 :2 0m :0 :N 0:0N 3.0.UCHN mo 0:000:000 000000 00000 x098 :00cmsom :0 :3000 00:0Hm :000 00 0:00:00 H0005 0:0 000006 >00 00 m0a0fl> .NH 0H00H 65 Table 13. Yields of dry matter and nutrient content of corn plants grown on Houghton muck after graded additions of zinc.a Zinc Nutrient addition Yield P K Ca Mgp meg/100 9 ppm g/plant ----------- % ----------- 0 0 1.37 .21 3.71 .69 .69 0.1 33 1.37 .33 8.7 .47 .41 0.2 65 1.04 .33 8.5 .47 .33 0.5 163 1.32 .30 8.2 .54 .44 1.0 327 1.55 .28 7.5 .61 .47 3.0 980 2.60 .23 5.2 .61 .38 6.0 1961 2.33 .23 5.9 .92 .40 9.0 2942 1.42 .21 6.9 1.39 .47 LSD (0.05) .45 .04 1.4 .11 .05 aEach value represents the average of 4 replications. 66 content was significantly lower than the control on all treatments of Zn. Ipfluence of Increasing Soil Zinc Concentration upon Soil Extractable Metal Concentrations The results of soil extractions are given in Table 14. Amounts of extractable Zn ranged from 14 to 2068 ppm, 9 to 876 ppm, and l to 880 ppm with 0.1 N HCl, 0.005 M DTPA, and 1 N NH4OAc extracting solutions, respectively. These data reveal that most of the added Zn was still in a rather solu— ble form while the plants were growing. Extractable Cu, Fe, and Mn was not significantly affected by Zn additions. 67 .m.z m.a .m.z and cm 00 Amo.ov :00 III m.o o.H omm mhw mmoN Nva o.m III v.0 0.0 mhv mNm tha Head 0.0 0.0 m.N m.o and H00 H00 omm o.m In: m.v 0.0 mN omN HvN NNM o.a In: N.v m.o ma 00H NNH mma m.o III m.m m.o m mm mm mm N.o III m.v m.o N 0N 0N mm H.o III m.v 0.0 H m «a o o IIIIIIIIIIIIIIIIIIIIIIIIIII sum Illnllllllllllaullllllul 8:: ,m ppHmv0E 6.05302 I498 I000 6.00402 I498 I000 5000000 2 H z moo.o 2 amp 2 H z mon.b z H.p 0:0n .0 ism 0:000:000 0:000000x0 0:0 ma000z 0.0.:000 £003 0:00:000 an 00300000 0:00 00 0:0000000 000000 00000 :00: :00smaom :0 00000: 00000000 00 000>0200 :000000000 .va 00:09 68 .m:0000000m00 q 00 00000>0 0:0 00:0000000 0:00> 0000 .000800 :00000000 30000 0003 m00>00 00x002 0:0 .55080000 .55080000 m «.o m.o .m.z .m.z mm .m.z Amo.ov mm: 0.0 m.o 0m 0.0 cm em mvmm o.m v.0 m.o mm 0.0 «m an 00m0 0.0 3.o 0.0 00 m.0 00 30 omm o.m m.o m.0 mm 0.0 0mm 00 nmm 0.0 N.o m.0 mm 0.0 0mm 3N mo0 m.o nun m.o om m.0 «mm mm mm «.0 0.o 0.0 mm «.0 m0m mm mm 0.0 0.o ~.0 mm m.0 m0m mm o o IIIIIIItlllllllslllllllllII Ema IIIIIIIIIIIIIIIIIIIJIIII Ema m oo0\v0E unowmz 1009: I000 600002 10090 I000 c0000000 2(0) 2 mopqo z 040 z 0 z mooup z 0.o 6:00 GE GE 0:000:000 0:00000080 0:0 000002 lawsc0ucoov 30 00080 SUMMARY AND CONCLUSIONS Plant growth and heavy metal accumulation was influenced quite differently by Cd, Cr, Ni, and Zn. The addition of Cd resulted in delayed seedling emergence, stunting of plants, and yield reduction. Plant Cd concentration increased from 16 to 136 ppm at levels of 0.05 and 2.0 meg/100 g reSpective- 1y, indicating that Cd was readily available for plant uptake. Plants grown on Cr treated soils yielded significantly higher in dry weight compared to the control. A resultant chemical analysis of plant tissue showed no detectable Cr, however, a significant increase in Mn uptake was noted (9 to 49 ug per plant). The increase in plant growth may be due to a dis- placement of Mn from the soil complex with a resultant in- crease in available Mn for plant uptake. Soil chemical analysis revealed no increase in extractable Mn due to Cr treatments, however, extractable Fe was significantly de— creased due to increasing Cr treatments. This may be a pos- sible explanation of increased Mn uptake since soil Fe/Mn ratios affect plant Mn uptake. Soil applied Ni at rates of 1.0 to 3.0 meg/100 9 increased plant growth significantly over the control. Rates of Ni above 3.0 meq/lOO 9 reduced plant growth significantly indicating a probable Ni toxicity. Foliage color of plants receiving rates of Ni up to 3.0 meq/ 69 70 100 g was no different than the control. Plants grown on soils receiving Ni treatments higher than 3.0 meq/lOO g were different with interveinal chlorosis at the 6.0 meg/100 9 rate and a browning of the leaves and eventual death of the plant at the 9.0 meq/lOO 9 Ni addition. Plant Ni concentra- tions were increased significantly over the control. When levels of Ni in plant tissue rose above 24 ppm the dry weight was decreased significantly due to Ni toxicity. The increase in growth at the lower levels of soil Ni may be due to a dis- placement of Mn or Cu with a subsequent increase in Mn and Cu uptake similar to the phenomenon with the Cr treatments. Soil analysis revealed that DTPA extractable Fe decreased with increasing Ni rates. Soil Zn treatments increased growth at two rates (3.0 and 6.0 meg/100 9). Plant size and foliage color with all Zn treatments were similar to the con- trol. Chemical analysis of plant tissue revealed increasing concentrations of Zn with corresponding increasing Zn treat- ments (74 to 1763 ppm at the 0 and 9.0 meq/lOO 9 rates). The high Zn accumulations in plant tissue indicate that applied Zn was readily available for plant uptake. C0pper uptake increased or decreased with increasing or decreasing plant growth, indicating Cu was not influenced by Zn treatments. The soil extractants varied greatly in their ability to extract metals from the soil. Both 0.1 M HCl and 0.005 M DTPA worked well in extracting heavy metals and were about equal in amounts extracted. 1 M NH4OAc was less effective than 0.1 M HCl or 0.005 M DTPA in terms of amounts of metals 71 extracted, however, each extractant removed increasing amounts of metals with increasing metal rates with the exception of the Cr treatments in which only 0.1 M-HCl removed Cr. Soil extraction of the metals indicates Cd, Ni, and Zn were in a rather soluble form in the soil while Cr was in a form which was unavailable. Plant chemical analysis generally, if not wholly, agree with this obser- vation. In terms of potential plant toxicity the metals would be arranged in the following order from greatest to least toxic: Cd>Ni>Zn>Cr. LI TERATURE CI TED 10. 11. LITERATURE CITED Allaway, W.H. 1968. Agronomic controls over environ- mental cycling of trace elements. Advance. Agron. 20: 235-274. Bingham, F.T., and M.J. Garber. 1960. 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