Browsing by Author "Hawkins, George W."

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    Boron chemistry in selected Virginia soils and hydroxy aluminum and iron systems
    Jin, Ji-yun (Virginia Polytechnic Institute and State University, 1985)
    Greenhouse and laboratory experiments were conducted to investigate the distribution of native B, the availability of native and applied B in 14 Virginia soils and the specific reactions of B in soil and hydroxy Al and Fe systems. Total B in the 14 soils ranged from 21.5 to 96.3 mg kg⁻¹. Only a small portion of the total B was in soil solution, non-specifically and specifically adsorbed forms and Mn minerals. These fractions of B are readily available to plants. A large part of the total B was associated with non-crystalline and crystalline Al and Fe minerals and soil silicates. These forms of B contribute little to B absorption by plants. Hot water soluble B, NH₄-acetate extractable B, mannitol exchangeable B and Mehlich III extractable B from the soils closely correlated with the concentrations in corn plants from native B in the greenhouse experiment. A yield response of corn plants to B application did not occur on the soils. Both tissue B concentration from applied B and maximum B adsorption by the soils closely correlated with soil clay, hydroxylamine hydrochloride extractable Mn and NH₄—oxalate (pH 3.25) extractable Al and Fe (under UV light). These data indicated that soil clay and Al-, Fe- and Mn-oxides and hydroxides have high affinities to adsorb B in plant unavailable forms. Boron adsorption on both gibbsite and goethite was pH and temperature dependent. At pH 6.5, boric acid was major species in the system and B was absorbed by the negatively charged surface of gibbsite and the positively charged surface of goethite. At pH 10, borate was primarily species in the system and B was adsorbed on negatively charged surfaces of both minerals. Boron adsorption was greater at pH 10 than at pH 6.5. An increase in temperature increased B adsorption on both minerals at both pH levels. This indicated that the B adsorption was an exothermic process. Boron adsorption on gibbsite and goethite shifted the ZPC of the minerals downward. This verified that specific B adsorption occurred on the surfaces. Aluminum substitution in goethite increased the affinity of the surface for B adsorption.
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    Corn response to long-term application of CuSO₄, ZnSO₄ and Cu-enriched pig manure
    Gettier, Stacy W. (Virginia Polytechnic Institute and State University, 1986)
    Three studies, two field and one laboratory, were performed to evaluate Cu or Cu and Zn from either sulfate sources or Cu-enriched pig manure. The studies were designed to investigate the effects of Cu and Zn in soils and corn (Zea mays L.). The first field study consisted of continuing a longterm field experiment which was established in 1967 to evaluate corn response and changes in a Davidson clay loam soil to yearly additions of Cu and Zn sulfates. In 1983, the 17 annual additions of Cu and Zn resulted in cumulative totals of 280 kg Cu and 560 kg Zn ha⁻¹. These Cu and Zn additions, either alone or together, did not cause any grain or stalk yield decreases. The DTPA extractant effectively separated all soil treatment levels for both Cu and Zn. Copper concentrations in the blades and grain were not related to soil additions of Cu or Zn. However, Zn concentrations in blades and grain were directly related to each other, r=0.87**, to soil Zn treatment levels and to DTPA extractable Zn. The second field experiment was designed to evaluate the effects of soil application of Cu-enriched pig manure and CuSO₄ on corn. The five treatments in each of three field locations consisted of a control, low and high Cu-enriched pig manure levels, and Cu, as CuSO₄, equivalent to Cu amounts in the manure. The soils varied in texture from clay loam to fine sandy loam, and ranged in CEC from 5 to 12.3 cmol(+) kg⁻¹. Copper-enriched pig manure, containing 1285 mg Cu kg⁻¹, was produced by pigs fed diets supplemented with 242 mg Cu kg⁻¹. After six years, 198 mg Cu kg⁻¹ had been applied by the high treatments. The DTPA extractable Cu was not related to leaf nor grain Cu levels but was linearly related, r=O.95**, to applied Cu. No nutrient deficiencies or toxicities were observed. The third study was a laboratory incubation of added Cu. The 15 soils ranged from 54 to 489 mg kg⁻¹ in clay and from 5.4 to 7.4 in pH. Extractable Cu had simple correlations with five soil properties, clay, surface area, hydrous Al, hydrous Fe, and hydrous Mn. Three treatments, a control and 22 kg ha⁻¹ Cu as CuSO₄, and as Cu-enriched pig manure (equivalent to 975 mt wet manure ha⁻¹), were applied to the soils at 33 k Pa moisture. Copper was extracted in the following order for the control and CuSO₄, treatments: AlCl₃ in O.5M HC1 > EDTA > DTPA. A different order of Cu extraction occurred for the Cu-enriched pig manure treatment such that EDTA > DTPA > AlCl₃ in 0.5M HC1. Extractable Cu decreased with time regardless of Cu source.
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    Effect of sulphur fertilization on growth and chemical composition of sorghum (Sorghum Bicolor L.) and on utilization of sorghum silage fed to wethers
    Ahmad, Muhammad Rashid (Virginia Tech, 1991-05-24)
    Sulphur (S) is an essential element for plant and animal nutrition, but widespread deficiencies of S occur world wide. Current recommendations for nitrogen (N):S ratios are 15 to 18:1 and 10 to 12:1 for plant and animal nutrition, respectively; but recent information suggests these may not predict animal response. Sorghum is an important crop, particularly in drier climatic regions but little is known concerning S-nutrition for sorghum growth or utilization of S-fertilized forages. Sorghum "Pioneer 947" was grown on a Lucy loamy sand (loamy, siliceous, thermic Arenic Kandiudult) in King William County, VA, with and without S fertilization (0 vs. 138 kg S ha⁻¹ as ammonium sulphate) in a randomized block design with four replications. Sulphur fertilization decreased (P < 0.05) soil pH and increased soil S in the 0 to 25 cm (P < 0.08) and 25 to 50 cm (P < 0.05) soil layers. An increase in Mehlich-I extractable soil P, Mn (P < 0.05) and soil N0₃-N (P < 0.06) at surface 25 cm layer occurred with S-fertilization. At harvest, S-fertilization increased (P < 0.05) S and water soluble carbohydrates and decreased (P < 0.05) N:S ratio and P concentration in whole plants. Sorghum leaves were higher (P < 0.05) in N, S, Ca, Mn and Cu in S fertilized compared to non-S fertilized sorghum. Sulphur fertilization decreased (P < 0.05) concentration of hydrocyanic acid (HCN) in the upper three leaves. A greenhouse experiment was conducted with the Lucy soil and 'Pioneer 947' sorghum to further investigate effects of fertilization (0, 70, and 140 kg S ha ⁻¹) as ammonium sulphate in a completely randomized design with five replications. Sulphur application decreased soil pH, and extractable soil K linearly (P < 0.01), and increased extractable soil S linearly (P < 0.01).
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    Effects of tillage and nitrogen fertilization on nitrogen losses from soils used for corn production
    Menelik, G.; Reneau, Raymond B.; Martens, David C.; Simpson, Thomas W.; Hawkins, George W. (Virginia Water Resources Research Center, Virginia Polytechnic Institute and State University, 1990-12)
    Research was conducted in soils of the Chesapeake Bay area to determine the effects of tillage practice and nitrogen (N) fertilizer application rates on N leaching from corn fields. Three well known computer models (NTRM, CERES-Maize, and VT-MAIZE) were tested to determine their ability to predict the distribution of N in (a) soil and crop, (b) the components of the N cycle, and (c) corn yields. To accomplish the above objectives, two field sites were selected on agronomically important soils for either a corn (Zea mays L.)-wheat (Triticum aestivum L.)-soybean (Glycine max [L.] Merr.) or a continuouscorn rotation. The corn-wheat-soybean rotation was located on a Suffolk sandy loam soil (coarse loamy, siliceous, thermic Typic Hapludult) in the immediate Chesapeake Bay drainage basin. The continuous-corn rotation was located on a Groseclose silt loam soil (clayey, mixed, mesic Typic Hapludult) typical of finer-textured soils located in the upper reaches of tributaries that drain into the Chesapeake Bay. Management practices evaluated included tillage system and rate, source, and time of N application. Specifically, we looked at conventional vs. no-till; inorganic N vs. sewage sludge; preplant vs. split application of N; and a variety of N application rates. The N treatments for corn were 0, 75, 150, and 225 kg N ha-1 applied preplant; 150 kg N ha-1 applied 4 weeks after emergence; and 150 kg of mineralizable N ha-1 from anaerobically digested and either lime- or polymer-conditioned sewage sludge. The N treatments for wheat were 20 kg N ha-1 applied in the fall and 30, 60, or 90 kg N ha-1 applied in the spring; 60 kg N ha-1 split application; and 80 kg of mineralizable N ha-1 applied in the fall from either lime- or polymer-conditioned sewage sludge. In the Groseclose soil, there was an increase in total yield and N uptake when sewage sludge was applied compared to the split and preplant application of inorganic N. There was no difference between polymer-or lime-conditioned sewage sludge application. Also, there were no differences between preplant and split application of N. Where no-till was used, there was an increase in both yield and N uptake compared with conventional till. In the Suffolk soil, tillage management did not influence yield or N uptake where time and source of N application were studied. This lack of response on the Suffolk soil is attributed to severe moisture deficits that were present during the growing season on this coarse-textured soil. Nitrogen losses from the soil profile were directly related to the quantity of N remaining in the upper 1 m of the soil profile after the crop was harvested. Larger quantities of N were lost from the Groseclose soil where conventional till was employed during the first year of the study. This was attributed to enhanced mineralization where no-till was converted to conventional till and to lower yields and lower N recovery with conventional till. Losses of N tended to be higher from the conventional till plots because of the larger quantities remaining at the end of the growing season. It should be noted that the years during which these xvii studies were conducted were extremely dry, and the in the Groseclose soil where no-till management was employed resulted in increased yield and increased N recovery. This study also emphasizes the need for better methods for making N recommendations for crop production. The model performances varied from year to year and from one tillage practice to another. Because they were written for average soil and climatic conditions, they did not make satisfactory predictions in many instances. Such models require adjustment to reflect the moisture stress conditions that often prevail in this region for corn production.
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    Estimating daily green leaf area index for corn in Virginia
    Ebodaghe, Denis Abumere (Virginia Polytechnic Institute and State University, 1986)
    A model to predict the daily green leaf area index (GLAI) for corn has been developed for Indiana conditions. Using daily maximum and minimum temperatures the GLAI was predicted for the vegetative stage, reproductive and grain filling stage, and the leaf senescing stage of corn. Predictions of GLAI for corn can be made on a daily basis from the day corn is planted until it is harvested for grain. The GLAI model was tested under Virginia conditions using green leaf area measurements collected from corn plants grown on Davidson silty clay loam, Davidson silty clay, and Mayodan sandy loam soils in the Piedmont region of the State. Maximum and minimum temperature data were also collected at the three sites. Measurements were made for two growing seasons using corn hybrid Pioneer 3369A, three plant population densities and two irrigation schedules. Short duration temperature data were also collected to compare with the daily maximum and minimum temperature data for the Mayodan site. Also a combination of soil temperature at 10 cm depth and air temperatures were used for the temperature functions accumulated from date of planting at the Mayodan site. Results of this study show that the predicted and measured GLAI values compare favorably under irrigated conditions on the Davidson soil. The results were not as favorable on the irrigated corn on the Mayodan soil. When the corn is subjected to severe moisture stress on either soil, GLAI cannot be predicted with this model. Short duration temperature data resulted in a better prediction of GLAI on the Mayodan soil. When applying nitrogen fertilizer to the corn through the irrigation system through the grain filling stage, the measured GLAI values compared favorably with the predicted GLAI values. However, the application of nitrogen and sulfur fertilizer together resulted in GLAI being maintained above that predicted for a longer period of time during the grain filling stage before its decline.
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    Evaluation and calibration of soil tests for available zinc
    Alley, Marcus M. (Virginia Tech, 1971-06-02)
    The results of the research show that either the EDTA-(NH4)C03 procedure or the multivariate regression equation could be used to estimate the Zn supplying powers of Virginia soils. It was pointed out that the critical levels obtained for the procedures are considered tentative and that the calibration should be continued as more field data become available.
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    An evaluation of production and marketing strategies for eastern Virginia cash grain producers
    Groover, Gordon E. (Virginia Tech, 1988-04-05)
    Eastern Virginia grain producers face production and marketing decisions under conditions of considerable yield and price variability. Traditionally MOTAD and other risk programming models have relied on the variability of historical returns series as a proxy for the risk an individual producer experiences. The mean forecast deviation method provides an alternative to the standard method of calculating deviations for MOT AD models. This method was applied to an eastern Virginia cash grain farm to provide a farm plan based on expected prices during the first week of February. The acreages of com, soybeans, and small grains were specified based on soil type, government program participation, sales at harvest, storage, pre-harvest hedging, and post-harvest hedging. The expected farm plans for the 1987 crop year resulted in participation in the government commodity programs at all levels of risk aversion and for each crop and soil type. Elimination of government commodity programs from the model resulted in two major findings: wheat and barley doubled cropped with soybeans preformed well on both soil types and at all levels of risk aversion, and given 1987 expected prices, idling lower quality land was a profitable decision at all levels of risk aversion.
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    Fertilizer facts
    Donohue, Stephen J.; Hawkins, George W. (Virginia Cooperative Extension Service, 1986-01)
    Presents facts on fertilizers.
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    Nitrification inhibition by metalaxyl as influenced by pH, temperature, and moisture content in three soils
    Moore, J. Michael (Virginia Polytechnic Institute and State University, 1989)
    Metalaxyl, [N—(2,6-Dimethylphenyl)-N-(Methoxyacetyl)-alanine methyl ester], is used extensively in tobacco (Nicotiana tabacum L.) production for prevention of black shank (Phytophthora parasitica Dast. var. nicotianae), blue mold (Peronospora tabacina Adam), and damping-off (Pythigm spp.). Metalaxyl is also patented as a nitrification inhibitor, although not marketed for that purpose. Proper maturity and ripening of flue-cured tobacco depends on an adequate supply of N through the time of removal of the inflorescence, with a declining supply of N from that point. Use of a chemical which might prolong the availability of N in tobacco could delay maturity and reduce the quality of the cured leaf. These studies were conducted to determine whether metalaxyl might inhibit nitrification under a broad range of soil physical and environmental conditions prevalent in the tobacco producing areas of Virginia. The influence of soil type, soil pH, soil temperature, and soil moisture on inhibition of nitrification by metalaxyl (1 mg kg⁻¹) were investigated in three soils used extensively for tobacco production. Soils used in the study were Cecil sandy loam (clayey, kaolinitic, thermic Typic Hapludult), Appomattox fine sandy loam (clayey, mixed, thermic Typic Kandhapludult), and Mattoponi sandy loam (clayey, mixed, thermic Typic Hapludult). Metalaxyl did not inhibit nitrification under any of the conditions studied. However, NO₂⁻ accumulation with metalaxyl was sometimes greater than the control, especially at high pH (7.0) in the Cecil and Appomattox soils, and at 10 and 20°C. Nitrite and NO₃⁻ accumulations from four rates of metalaxyl (1, 5, 25, and 125 mg kg⁻¹) were compared with those of an untreated control and a nitrapyrin standard over a seven week soil incubation period in further studies using the same soils and adjusted pH levels. Significant NO₂⁻ accumulation occurred during the first week after treatment at high pH in all soil types, with 5, 25, and 125 mg kg⁻¹ metalaxyl. Only the 125 mg kg⁻¹ metalaxyl treatment caused NO₂⁻ accumulation at the high pH in all soils beyond the second week after treatment, with the peak occurring in most cases between weeks three and four. Nitrate accumulation proceeded normally in all soil types and pH levels except with treatments of 25 and 125 mg kg". Nitrate accumulations with 25 mg kg⁻¹ were similar to those for nitrapyrin. The 125 mg kg⁻¹ rate was consistent in causing near total inhibition of NO₃⁻ accumulation at all pH levels in all soils. Nitrate accumulation tended to be lower at lower soil pH levels compared to the highest pH for all soils. Little difference in nitrification due to soil appears to be evident. Use of metalaxyl at recommended rates of 0.25 to 1.5 mg kg⁻¹ would not be expected to inhibit nitrification.
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    Nutrient composition of ensiled alfalfa and corn forages grown in Virginia
    Ahmad, Muhammad Rashid (Virginia Tech, 1991-05-24)
    Corn (Zea mays) and alfalfa (Medicago sativa) silages are used extensively in Virginia. A survey was conducted to determine chemical composition of these two forage silages grown in five geographical regions of Virginia; Eastern Virginia (EV), Northern Piedmont (NP), Southern Piedmont (SP), Shenandoah Valley (SV), and South-Western Virginia (SWV). A total of 889 samples of corn silage, 106 of ammoniated corn silage and 247 of alfalfa silage collected during 1988 and 1989 from 76 counties, were analyzed for fiber, N, and macro- and micro-nutrients. Chemical composition of the silages was correlated with S applied in fertilizer or manure. Data were compared with critical levels of mineral requirements of various classes of livestock. Alfalfa silage was higher (P < 0.05) in crude protein (CP), P, K, Ca, Mg, S, Mn, and Fe than com silage. Ammoniated corn silage was higher (P < 0.01) in CP and NS ratio, and lower in P, S (P < 0.01) and K (P < 0.05) concentrations than non-ammoniated corn silage. For lactating dairy cows, 86 and 95% of corn silage and ammoniated corn silage, respectively, grown throughout the State were deficient in P. Information supplied by farmers suggested that manure application increased P concentration of these forages. Over 90% of all corn silage would not have met the Ca requirements of dairy cows, however, 97% of the alfalfa silage was excessive in Ca concentration for dairy cows and could have served as a Ca supplement to the diet. Nitrogen:S ratio indicated S deficiency (N:S ratio > 12) in 34, 89 and 41% of samples of corn silage, ammoniated corn silage and alfalfa silage for dairy cattle and in 85, 96 and 91% of the respective silages for sheep (N:S ratio > 10). Based on S concentrations, 96% of corn silage and ammoniated corn silage grown throughout Virginia were S deficient for dairy cows while 72% of corn silage and 86% of ammoniated corn silage were deficient in S for sheep. Sulphur concentrations in silages did not indicate S deficiencies for plant growth. Over 60% of corn and alfalfa silages would not have met nutritional requirements for Zn and Cu in lactating dairy cows but requirements for Mg and Mn would have been supplied by more than half of the silages produced in Virginia. Regional/ geographical variations in almost all the nutrients were observed for both forages. Generally, corn silage grown in EV was lower in CP, TDN, Mg, and Mn and was higher in ADF compared to silage grown in the rest of the State. Lower CP, Ca, and S were observed in alfalfa silage grown in EV compared to the mean of other regions. Generally, higher N:S ratio in corn and alfalfa silages and lower P were found in alfalfa silage grown in Western Highlands compared to Piedmont region. Also CP and Ca were lower in corn silage grown in SWV compared to SV while Mg was lower in either silage grown in SV compared to SWV region. In general, concentrations of P, Ca, S, Zn, and Cu in corn silage and ammoniated corn silage were widely deficient ( > 70% samples deficient) for dairy cattle, and deficient in S for sheep. Magnesium deficiencies were less frequent. In alfalfa silage concentrations of Zn, and Cu were low for dairy cows. Nitrogen:S ratios indicated S deficiency for livestock, particularly in sheep and lactating dairy cows.
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    Response of corn to high levels of CuSO₄ and ZnSO₄ applications
    Wijesundara, Chandra (Virginia Tech, 1988-11-05)
    High levels of Cu and Zn application to agricultural soils are considered to pose a potential hazard to plants and animals. The levels of Cu and Zn which can be safely added to cropland have yet to be established. This study was conducted on a Davidson silty clay (Rhodic Paleudult) to determine the response of corn (Zea mays L.) to cumulative application of up to 469 kg Cu and 1032 kg Zn ha⁻¹ as sulfates over the 22-year period from 1967 through 1988. Neither corn grain nor silage yield was affected by the metal additions even though the cumulative amount of Cu and Zn added exceeded the maximum allowable Cu and Zn loading rates based on the U.S. Environmental Protection Agency guidelines (i.e., 250 kg Cu and 560 kg Zn ha⁻¹) for this soil. The twenty-first annual application of Cu as CuSO₄, increased Cu concentrations in ear leaves. However, Cu concentrations in ear leaves were unaffected by the twenty-second year of Cu application. Concentrations of Zn in ear leaves were increased by the high level of Zn application during the two years of the study. Twenty-first year Cu and Zn concentrations in com grain were not increased by the high levels of Cu and Zn sulfates. All grain and ear leaf Cu and Zn concentrations were within the normal ranges from the high amount of metal application. The DTPA extractable Cu and Zn in the soil increased with an increase in level of applied Cu and Zn. More Cu and Zn were extracted from the soil by the Mehlich-3 method than by the DTPA method. This higher rate of extraction was attributed to the ethylenediaminetetraacetic acid (EDTA) in the Mehlich-3 solution.
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    Response of corn to high levels of CuSO₄ and ZnSO₄ applications
    Winarko, Clementinus (Virginia Tech, 1985-06-05)
    Copper and Zn deficiencies of crop plants occur in various areas throughout the world. The sulfate forms of Cu and Zn are generally used to correct these micronutrient deficiencies. In agricultural practices, Cu and Zn are applied to soils not only as a fertilizer but also as manures, pesticides and waste materials such as sewage sludge. High levels of Cu and Zn application to agricultural soils are considered to pose a potential hazard to plants and animals. Research findings have not established Cu and Zn levels that either injure plants or increase Cu and Zn concentrations in edible plant portions to undesirably high levels. Published data on the fate of applied Cu and Zn indicate that there is little, if any, downward movement of these micronutrients in soils and that, with time, applied Cu and Zn revert to plant unavailable forms in soils.
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    Response of corn to manganese application on Atlantic coastal plain soils
    Uribe Botero, Eduardo (Virginia Tech, 1985-05-15)
    Although corn plants are tolerant of low levels of available soil Mn, Mn deficiencies in corn were suspected on soils where Mn applications had previously increased soybean seed yields. Five experiments were conducted in farmer's fields to evaluate the response of corn to Mn applications. Three band Mn and two broadcast Mn studies were conducted in five field experiments on Atlantic Coastal Plain soils. The mean increase in corn grain yield in the band studies on three soils was 960 kg ha⁻¹. Corn grain yields were not increased in the broadcast Mn studies on Slagle and Dragston fine sandy loams. Manganese uptake from the Slagle soil was so high that Mn deficiency did not occur; whereas, Mn uptake from the Dragston soil was so low that the deficiency was not completely corrected by up to 24 kg Mn hha⁻¹ as broadcast MnSO₄.
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    Tillage effects on soil-water-air matrix and prediction of soil bulk density from cone index data
    Jayatissa, Dangallage Nimal (Virginia Tech, 1990-02-05)
    Conventional farming systems create socio-economic problems through increased production costs and loss of the soil and chemicals that are washed from the farmlands. Even though no-till farming systems can increase farm profit and reduce environmental degradation, soil compaction can negate the advantages of no-till farming when no-till systems are used continuously under certain soil and climatic conditions. One objective of this study was to evaluate the long-term effects of the no-till method on bulk density, capillary porosity, noncapillary porosity, void ratio, and cone index of the soil. Although tillage affected cone index significantly, moisture variations caused difficulty in interpreting the results. No statistically significant differences in other parameters were found among no-till, conventional till, and control fallow treatments within each of three cropping seasons. However, within each tillage treatment these parameters showed significant variations between test seasons. When the soil bulk density data is required at close depth intervals, the core sample method becomes laborious while its use is limited by soil type and moisture conditions. The neutron probe densitometer is difficult to use in tillage studies due to practical problems. Among the predictive models for bulk density, some require parameters determined through expensive laboratory procedures while others have not been proven to work in field conditions. Therefore, the second objective was to develop a model to predict soil bulk density using cone index and moisture content data for a Virginia soil. Two separate models have been developed for top and subsoil layers using remolded natural soil samples. The topsoil model predicted bulk density close to the actual data taken in recently disturbed soils. One cropping season after plowing, predicted values were about 10% higher than the actual, a result which could be due to the aging effect. The subsoil model, on the other hand, under-predicted soil bulk density by about I5% After the model coefficients for a particular soil are determined through laboratory tests, cone index and moisture data can be used to predict bulk density in that soil. This procedure may save time and expense in future research on soil compaction.
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    Uptake of native and applied copper by corn and wheat as related to soil properties
    Perera, Nimal F. (Virginia Polytechnic Institute and State University, 1986)
    Copper and Zn deficiencies of crops have been reported in various parts of the world. To prevent these deficiencies sulfate forms of Cu and Zn are generally used. In addition, Cu and Zn also are contributed to soils by manures, pesticides, and waste materials such as sewage sludge. An insufficient supply of Cu or Zn may reduce crop yield; whereas, excess Cu or Zn may be detrimental to both plant and animals. The field phase of this research was conducted on a Davidson silty clay to evaluate corn response to high levels of CuSO₄ and ZnSO₄ applications up to 338 kg Cu and 830 kg Zn ha⁻¹. The results of this research indicated that corn grain and stalk yields of corn were not affected (α= 0.05) by high levels of CuSO₄ and ZnSO₄ either alone or combined. Copper concentration in neither corn grain nor ear leaves was affected (α = 0.05) by the Cu application. Zinc concentrations in both grain (α = 0.01) and ear leaves (α= 0.001) were increased by ZnS04 application. Application of ZnSO₄ increased the Cu in the labile pool, whereas CuSO₄ fertilization did not affect Zn in the labile pool. A greenhouse experiment was conducted to examine the response of wheat to Cu application on 14 soils. Treatments in this study were a control and 5.35 mg Cu kg⁻¹ as CuSO₄. Dry matter yields were not affected (α = 0. 05) by Cu fertilization whereas tissue cu levels were increased (α = 0.001). Copper uptake was highly correlated with DTPA-Cu (r = 0.80, α = 0.001), but weakly correlated with Mehlich III-Cu (r = 0.28, α = 0.05). The DTPA-Cu showed high correlations with clay content (r = 0.98, α = 0.001) and SA (r = 0.93, α = 0. 001); whereas, Mehlich III-Cu did not correlate with these variables (α = 0.05). A second greenhouse experiment was conducted with 10 Virginia soils to evaluate the response of corn to Cu fertilization. Treatments were a control and 5.35 mg Cu kg⁻¹ as CuS0₄. Dry weights of corn on the 10 soils were not affected (α = 0.05) by Cu application; whereas, tissue Cu levels were increased by the applied Cu (α = 0. 001). Copper uptake by corn plant correlated with DTPA-Cu (r = 0.62, α= 0.001) and with soil pH (r = 0.35, α = 0.05). There was no correlation of organic matter with Cu uptake (α = 0.05). Both DTPA-Cu and Mehlich III-Cu were unrelated to either organic matter or soil pH (α = 0.05).