Browsing by Author "Donohue, Stephen J."

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    Agronomy Handbook
    Brann, Daniel Edward; Abaye, Azenegashe Ozzie; Peterson, Paul R.; Chalmers, David R.; Whitt, David L.; Chappell, Glenn F.; Herbert, D. Ames Jr.; McNeill, Sam; Baker, James C.; Donohue, Stephen J.; Alley, Marcus M.; Evanylo, Gregory K.; Mullins, Gregory L.; Hagood, Edward Scott; Stallings, Charles C.; Umberger, Steven H.; Swann, Charles W.; Reed, David T.; Holshouser, David L. (Virginia Cooperative Extension, 2009-05-01)
    Provides readers with a source of agronomic information such as field crops, turfgrasses, variety selection, seed science, soil management, nutrient management and soil suitability for urban purposes that does not change frequently - pesticide and varietal information changes frequently and is therefor not included.
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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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    Fertilizer facts
    Donohue, Stephen J.; Hawkins, George W. (Virginia Cooperative Extension Service, 1986-01)
    Presents facts on fertilizers.
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    Fertilizing the Vegetable Garden
    Relf, Diane; McDaniel, Alan, 1948-; Donohue, Stephen J. (Virginia Cooperative Extension, 2009-05-01)
    The best way to determine fertilizer needs is to have the soil tested. This publication gives the reader advice on ways to understand fertilizers, application methods, and timing of fertilizer application.
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    Long-term copper availability and adsorption in a sludge-amended Davidson clay loam
    Anderson, Martha Ann (Virginia Tech, 1997-04-04)
    A single application of aerobically digested sewage sludge was applied by Rappaport et al. (1988) in 1984 at rates up to 210 dry Mt ha⁻¹ on a Davidson clay loam (clayey, kaolinitic, thermic, Rhodic KandiuduIts). The heavily contaminated sludge supplied up to 760 kg Cu and 620 kg Zn ha⁻¹, which are below current cumulative limits, but above annual loading limits for these metals (USEPA, 1993). Rappaport et al. (1988) reported an increase in DTPA extractable Cu and Zn with increasing sludge rate. They observed a linear increase in com yields with an increase in sludge rate, which was attributed to high levels of available N supplied by the sludge. In the present residual study, conducted at the same research site, DTPA extractable Cu and Zn followed the trend observed by Rappaport et at. (1988). However, a linear decrease in corn and sorghum yields was observed with increasing sludge rate. The sludge-related decrease in yields was attributed to phytotoxicity (probably a combination of Al, Cu, Mn, and Zn) induced by low soil pH levels. Whole plant tissue concentrations of eu and Zn at the high sludge rates were above the normal range, however grain concentrations were within the normal range. An adsorption study was conducted, in which soils were amended with Ca(OH)₂ and Al₂(S0₄)₃, to ascertain the effect of decreased pH on Cu adsorption on the soil. Copper adsorption maxima decreased with a reduction in soil pH in all treatments. The effect of ionic strength on Cu adsorption was also investigated. Regardless of pH or ionic strength, Cu adsorption increased with an increase in sludge rate. This adsorption increase was attributed to the higher organic matter content of the sludge treatments. The organic matter at the highest sludge rate was approximately double that of the control after 11 years. The adsorption study shows that sludge amendment has long-term effects on metal retention in soils and the field study reveals that careful management of sludge-amended soils is necessary to prevent phytotoxicity.
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    Long-term effects of copper rich swine manure application on continuous corn production
    Anderson, Martha Ann (Virginia Tech, 1990-12-17)
    Three long-term field experiments were established in the spring of 1978 and continued through 1988 to evaluate corn (Zea mays L.) response to high Cu levels from Cu rich swine manure and CuS0₄ applications. The field research was conducted on soils with diverse properties, i.e., on a Bertie fine sandy loam (Aquic Hapludults), a Guernsey silt loam (Aquic Hapludalfs), and a Starr-Dyke clay loam (Fluventic DystrochreptsTypic Rhodudults). Three treatments in the long-term field experiments on the three soils were a control, annual applications of eu as eu rich swine manure, and annual applications of Cu as CuS0₄ equivalent to that in the manure. After the 11 years, 1109 mt ha⁻¹ of wet Cu rich swine manure were applied for the manure treatment. The Cu rich manure contained an average of 1316 mg Cu kg⁻¹, An average of 325 kg Cu ha⁻¹ added to the soils from the manure application over the 11 years exceeded U.S.E.P.A. guidelines for safe copper loading levels for cropland by 45 kg ha⁻¹. Copper concentrations in corn ear leaves were within the normal range of 3 to 20 mg kg⁻¹ where the 325 kg Cu ha⁻¹ were applied to the soil as either Cu rich manure or CuS0₄. Concentrations of Cu in the grain were also in the normal range of 1 to 5 mg kg⁻¹ where the high level of the two Cu sources was applied to soils. There was no decrease in corn yield on the three soils from application of either Cu source.
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    Nitrogen Management in No-till Winter Wheat Production Systems
    Gaidos, Joan Marie (Virginia Tech, 2001-04-12)
    Determining optimum N fertilization rate and timing is critical to improve yields and economic sustainability for no-till winter wheat (Triticum aestivum L.) in the Virginia Coastal Plain. Little data are available evaluating N management strategies, optimum N rate prediction methods, or potential NO3 leaching under no-till wheat in soils and climate similar to the mid-Atlantic region. The objectives of our research were: (1) to determine economic optimum N fertilization rates and timings; (2) evaluate selected methods for predicting optimum N rates at GS 25 and GS 30; and (3) measure NO3 leaching loss under selected N management strategies. Eleven experiments over three years evaluated N rates at GS 25 and GS 30. Six experiments over two years evaluated pre-plant and December or GS 25 N rates under no-till winter wheat in farm fields of the Coastal Plain region of Virginia. Nitrate leaching was measured under selected pre-plant and December or GS 25 N application rates. All sites represented common Coastal Plain soil types and cultural practices for no-till wheat production. Yield data were used to calculate economic optimum N rates for a range of combinations of N management strategies. Optimum N rates were regressed against tiller density at GS 25, and wheat tissue N content and SPAD chlorophyll meter readings at GS 30, to determine their effectiveness as predictors of the optimum N rate at GS 25 or GS 30. Tiller density was an effective predictor of optimum GS 25 N rate in these split application management strategies. However, wheat tissue N contents and SPAD chlorophyll meter readings were not effective predictors of optimum N application at GS 30. Yields across all experimental designs were affected by planting date. Timely planted no-till wheat consistently produced higher yields compared to late planted. Sites under continuous no-till production for 8 years or more also produced higher yields than sites under continuous no-till production for less than 8 years. Including an additional December N application with the more traditional N management strategy of pre-plant, GS 25 and GS 30 N applications improved yields. Nitrate leaching loss at selected pre-plant and December or GS 25 N rates was not higher than background check plot levels under timely planted no-till wheat. Additionally, economic optimum N application rates and timings at these sites did not produce NO3 leaching losses above background levels under timely or late planted wheat, except at one late planted site. These data indicate N application rates and timings in no-till wheat can be managed for improved economic sustainability and reduced environmental impact.
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    Precision Farming. A Comprehensive Approach
    Grisso, Robert D.; Alley, Marcus M.; McClellan, Phil; Brann, Daniel Edward; Donohue, Stephen J. (Virginia Cooperative Extension, 2005-09-01)
    Precision Farming (PF), also referred to as precision agriculture or variable rate technology, is the process used to vary management of crop production across a field. This publication introduces the principles and terminology used in PF. Crop producers can use this information to gain a working knowledge of PF and develop the ability to implement PF technologies in traditional crop production.
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    The Relationship Between Mineral Nutrition and Late-Season Bunch Stem Necrosis of Cabernet Sauvignon (Vitis vinifera L.) Grapevines
    Capps, Eric R. (Virginia Tech, 1999-04-13)
    Late-season Bunch Stem Necrosis (BSN) is observed as a necrosis of the cluster stem (rachis) that leads to shriveling of berries on the affected portion of the cluster. Field experiments were conducted over three years at two vineyards in northern Virginia to examine relationships between specific nutrients and the incidence of BSN of Cabernet Sauvignon grapevines. Nutrients, used alone or in combination, included nitrogen, magnesium, and calcium. During the 1997 and 1998 seasons at Leesburg vineyard, applications of nitrogen, magnesium, and calcium produced little change in bloom-time petiole mineral concentration. Fertilizer treatments appeared to have no effect on BSN incidence, but the incidence of BSN was less than or equal 1% in the control plots each year. During the 1996 season at Winchester vineyard, bloom-time leaf petiole and véraison rachis nitrogen concentration of unfertilized (control) vines were 0.80% and 1.16%, respectively. The corresponding control BSN incidence was 41% at harvest time. Application of nitrogen fertilizer at 112 kg/ha actual nitrogen increased bloom-time leaf petiole and véraison cluster stem nitrogen concentration to 1.85% and 2.18%, respectively. The corresponding BSN incidence was reduced to 14% at harvest time. BSN symptoms were not as pronounced during the 1997 season; however, all treatments, including the control plots, had elevated nitrogen levels in 1997. During the 1998 season, bloom-time leaf petiole and véraison rachis nitrogen concentration of unfertilized vines were 0.88% and 0.98%, respectively. The corresponding BSN incidence was 23% at harvest time. Application of nitrogen fertilizer again increased bloom-time leaf petiole and véraison rachis nitrogen concentration to 1.18% and 1.34%, respectively. Corresponding BSN was reduced to 3% at harvest time. Magnesium and calcium had no impact on BSN incidence; however, BSN symptoms were reduced when either was combined with nitrogen fertilizer. The relationship between mineral nutrition and BSN incidence at Leesburg was inconclusive. The BSN of Cabernet Sauvignon at Winchester was, however, positively associated with depressed bloom-time petiole total nitrogen concentrations. Véraison rachis analysis consistently revealed an increase in nitrogen concentration due to application of nitrogen fertilizer. Véraison tissue analysis may be a good diagnostic tool of vine nitrogen status. Magnesium and calcium appeared not to be involved in the disorder. The results illustrate that BSN-prone vineyards should be individually examined for nutrient imbalance or other stresses that may be contributing to BSN.
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    Relationships of soil test phosphorus with soil properties and phosphorus forms
    Wijesundara, Sunetra M. (Virginia Tech, 1996)
    A comprehensive approach to soil P management in agricultural systems requires a balance between nutritional enhancement of the soil and a reduction in adverse consequences on the environment. Evaluation of forms in which P is present in the soil, dynamics of P transformation across these forms, determinants of spatial and temporal distribution of P pools in the soil, and impacts of agricultural practices on the rate and direction of these reactions were the key objectives of the present investigation. Phosphorus extracted by the four widely used soil extractants, i.e., Bray 1, Mehlich 1, Mehlich 3, and Olsen, represented less than 25 percent of the total P content in 43 Virginia soils from the Coastal Plain, Piedmont, and Ridge and Valley regions. Correlation between Bray 1 (1 minute and 5-minute shaking), Mehlich 1, and Mehlich 3 extractable P was high: correlation of these extractants was poor with the Olsen procedure which extracted the lowest soil P contents. The Mehlich 3 procedure was more reliable in the extraction of labile P than the Mehlich 1 procedure in soils with a wide range of pH values. The Mehlich 3 procedure was less prone to extraction of plant unavailable, structurally adsorbed phosphorus, particularly in dithionite-citrate-bicarbonate extractable Al₂O₃ rich soils, than the other procedures. The process of P extraction by different extractants under varying physical and chemical conditions was satisfactorily explained by an acid-catalyzed nucleophilic substitution reaction mechanism. This mechanism satisfactorily links the solubilization of P from Al and Fe surfaces to the strength of nucleophilic agents such as OH⁻, CH₃COO⁻, CI⁻, F⁻, and H₂O, and to the acidity of the supernatant solution. Inorganic P fractionation was determined by the modified Chang and Jackson (1957) procedure of Peterson and Corey (1966) with several modifications, and the organic P analyzed by the Bowman (1989) method. The total P content of the 43 soils in this study ranged from 0.02% to 0.4%. Twenty six percent of the total P was in the labile to moderately labile pool, 49% in the non-labile pool, and 25% in the organic fraction. The distribution pattern of Fe-P, reductant soluble P, occluded P, residual P, and organic P fractions was directly related to soil Fe₂O₃ and clay contents. The Al-P content was not markedly influenced by the clay content or pH. It was concluded that Fe-P, a dominant labile P form in agricultural soils was transformed over time to reductant soluble P, the dominant P form in the soils. The reductant soluble P fraction, which increases with P fertilization and has higher solubility under reduced conditions, through erosion poses a major potential eutrophication threat to surface waters. The eutrophication potential is high in the Piedmont and high clay soils. Phosphorus adsorption in the Davidson and Tatum soils from the Piedmont physiographic region was well explained by the two-site-Langmuir adsorption model. The adsorption maxima was slightly (5%) decreased by long-term P fertilization over three decades. All soil inorganic and organic P fractions were increased by fertilizer application with the reductant soluble fraction increasing by 61 and 57 percent in the Davidson and Tatum soils, respectively. The residual effects of long-term application of P fertilizer increased labile P contents extracted by soil test methods, and in the Davidson soil the uptake from the residual fertilizer P was sufficient to maintain the tissue P concentrations of young corn seedlings at the sufficiency range.
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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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    Selected Topics For Raspberry Producers In Virginia
    Stiles, Herbert D.; Donohue, Stephen J.; Baker, James C. (Virginia Cooperative Extension, 2009)
    Discusses the importance of carefully selecting cultivars of raspberry plants, and locations best suited for growing them. Factors in selection of site include topography and soil type. Other factors for improving health and growth of raspberry plants, crop yield and fruit size include irrigation, and pre-plant site preparations.
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    Soil Sampling for the Home Gardener
    Hunnings, Joseph; Donohue, Stephen J.; Heckendorn, Steven E. (Virginia Cooperative Extension, 2009-05-01)
    This publication explains how to obtain representative soil samples and to submit them for analysis to the Virginia Tech Soil Testing Laboratory. It is an easy-to-learn process that will benefit you, your landscape and the environment.
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    Soil Sampling for the Home Gardener
    Hunnings, Joseph; Donohue, Stephen J.; Heckendorn, Steven E. (Virginia Cooperative Extension, 2019)
    How to collect, sample, and test soil. When and where to sample, equipment to use, where not to sample, soil sampling as a diagnostic tool, how to take a representative sample, how to take sub-samples, composite sample, complete the soil sample information sheet, results from test.
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    Some aspects of nitrogen nutrition on selected Ilex
    Gilliam, Charles Homer (Virginia Tech, 1977-09-05)
    Three holly cultivars, Ilex crenata, Thunb. 'Helleri' and 'Rotundifolia' and Ilex cornuta Lindl. et Paxt. 'Burfordi' were grown in 3 liter containers at 200, 300, 400 and 500 ppm nitrogen (N). Significant correlation coefficients were found between plant growth (dry wt accumulation) and both leaf N content and soil solution nitrates, while low correlation coefficients were found between soil nitrates and plant growth. Shoot growth of 'Helleri' and 'Burfordi' was not increased by N levels higher than 300 ppm while 400 ppm N was optimal for 'Rotundifolia'. The effects of 3N levels on tissue N fluctuations during a flush of growth on 'Helleri' were also studied. For all N levels, tissue N levels were shown to increase following the cessation of stem elongation until a level of tissue N was reached where a new flush of growth began. These N levels were approx the same for all N treatments. The time necessary to reach this level was dependent on the level of N added; 5 weeks for 300 ppm, 13 weeks for 150 ppm and 18 weeks for 50 ppm N. Once new growth began, tissue N levels began to decrease. The response of 'Helleri' to 15 fertilizer treatments consisting of different time and lengths was studied. Fertilizer applied during a period following the cessation of stem elongation and before the next flush resulted in greater total N and shoot growth, regardless of whether it was also applied during other weeks or not. Root growth was suppressed by 3 or more fertilizer applications, regardless of the time of application.
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    Trees and Shrubs for Acid Soils
    Appleton, Bonnie L.; Heins, Robert; Donohue, Stephen J.; Eaton, Gregory K.; Alleman, Dawn (Virginia Cooperative Extension, 2009-05-01)
    This publication reviews the planting guidelines for trees and shrubs for acid soils including plant and site selection, site preparation, tree and shrub preparation, and tree care and planting.
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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).