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Zinc sulfate (ZnSO4 · H2O) has traditionally been the “reliable” source of zinc (Zn) fertilizer, but other sources of Zn are also available. Some are derived from industrial by‐products, varying from flue dust reacted with sulfuric acid to organic compounds derived from the paper industry. The degree of Zn mobility in Zn sources derived from these various by‐products is related to the manufacturing process, the source of complexing or chelating agents (organic sources), and the original product used as the Zn source. Many claims are made regarding the relative efficiency of traditional inorganic Zn fertilizers and complexed Zn sources. The objective of this column study was to compare the mobility of several commercial Zn fertilizer materials (organic and inorganic) that are commonly used to correct Zn deficiencies in soils. The sources included three granular inorganic Zn sources, two granular organically complexed Zn sources, and liquid ZnEDTA. Soil columns were leached five times with deionize...

Micronutrient deficiencies in plants are common throughout the world. Many inorganic and organic fertilizers are manufactured and applied to soils and plants to correct micronutrient deficiencies. The objective of this article is to review current research and present our findings on factors that affect micronutrient fertilizer efficacy. In the United States, state laws regulate the “guarantee analysis” of fertilizers and essentially all states require that manufacturers meet a total analysis requirement. However, there is no consideration of micronutrient “availability” in this analysis. Our research has shown that Zn availability in granular fertilizer was related to water solubility (r2=0.92) and not total Zn content. The relative availability coefficients for organic and inorganic Zn fertilizers was also highly related to water solubility and independent of total Zn content. Because of this discrepancy, there are fertilizers in the marketplace that are very low in plant available micronutrien...

Zinc sulfate (ZnSO4) has traditionally been the “reliable” source of Zn fertilizer but other sources of Zn are also available. Some are derived from industrial by-products, varying from flue dust reacted with sulfuric acid to organic compounds derived from the paper industry. The degree of Zn availability in Zn sources derived from these various by-products is related to the manufacturing process, the source of complexing or chelating agents (organic sources), and the original product used as the Zn source. Many claims are made regarding the relative efficiency of traditional inorganic Zn fertilizers and complexed Zn sources. The objective of this greenhouse study was to determine the availability coefficients of several commercial Zn fertilizer materials (organic and inorganic) that are commonly used to correct Zn deficiencies in soils. We evaluated the dry matter production, total Zn uptake, and Zn concentration in corn (Zea mays L. cv. P3752) plants fertilized with six different commercial Zn fertilize...

The behavior of radionuclides of the uranium (U) and thorium (Th) decay series in terrestrial systems is of interest because of environmental effects of mining and disposal activities related to nuclear power plant fuels. The soil-plant relationships of U, Th, and polonium (Pb), and some other daughter radionuclides, notably radium ({sup 226}Ra), are not well understood. Most studies have been concerned with relative uptake of these radionuclides by various plant species. Plant concentrations have been related to total contents of these radionuclides in the soil as a plant/soil concentration ratio (CR), even though the fraction of these radionuclides, which may be available to plants, is not well known. These CR values have been used to predict transport of radionuclides and other elements of interest through the food chain as well as for other purpose including biogeochemical exploration for U. Little information is available on uptake and transport mechanisms of radionuclides in plants. However, the mechanisms relating to Ca uptake and translocation in plants may be similar to those of some radionuclides, especially {sup 226}Ra. Son chemical reactions of these radionuclides also have not been studied as well as those of plant nutrients, although knowledge of the effects of soil pH,more » soil texture, and organic matter content on uptake, as well as mobility in soil of these radionuclides, has been gained in recent years. 45 refs., 13 tabs.« less

Cation movement in soil under leaching conditions has been associated with N fertilization. Therefore, this study was conducted to determine whether the mobility of some heavy metals applied in the inorganic form or in sewage sludge is enhanced in the presence of various sources of N. Columns of heavy metal-amended soil in plastic well casings were cropped with tall fescue (Festuca arundinacea Schreb.) and leached three times with deionized H/sub 2/O. Heavy metal concentrations above check values were not detected in leachates from any column. Mobility of the heavy metals from the inorganic sources was slightly greater than that from the sewage sludge. Nitrogen fertilization did not affect the downward movement of Zn, Cd, Cr, Pb, or Ni in soil but enhanced uptake of these metals by fescue because of increased growth. These results suggest that heavy metal contamination of ground water is not likely in heavy textured soils when sewage sludge applications are accompanied by N fertilization, at least for short periods of time. 11 references, 1 figure, 4 tables.

Etude experimentale de l'absorption par du mais (Zea mays) et des bettes (Beta vulgaris) de Cd, Ni et Pb contenus dans des engrais au zinc prepares a partir de sous-produits industriels

A field experiment was conducted to determine uptake of Cd and other heavy metals by winter wheat (Triticum aestivum L.) from three diammonium phosphate (DAP) fertilizers containing 2, 74, and 153 ..mu..g Cd/g. A phosphorus-deficient Paden silt loam (Glossic Fragiudult, pH 4.7) was limed at two rates and treated with the DAP sources at a rate of 50 kg of P/ha (100 lb of P/sub 2/O/sub 5//acre). Grain yields were higher at pH 5.9 than at pH 5.1, were significantly increased by P applications, and results were similar using all DAP sources. Concentrations of Cd in both grain and straw were significantly increased only with application of high-Cd DAP to the low-lime soil. Cadmium concentrations in grain increased from 0.028 to 0.086 ..mu..g/g, and those in straw increased from 0.067 to 0.118 ..mu..g/g (dry weight basis) with application of low-Cd DAP and high-Cd DAP, respectively, and were lower on the high-lime soil. Concentrations of Cu, Mn, Ni, and Zn in both grain and straw were not significantly affected by DAP source. Results for a second year on the same plots limed to pH 5.8 and 7.0 and treated again with the same DAP sources were similar to those for themore » first year, except that heavy metal uptake was generally lower. Results suggest that Cd concentrations in wheat products are not significantly changed by the phosphate fertilization and crop production practices in general use in the United States at this time.« less

Greenhouse and laboratory experiments were conducted to characterize the chemical form or forms of Cd, which is a contaminant in phosphate fertilizers, in terms of plant availability and extractability from soil. Winter wheat (Triticum aestivum L.), cv. Nugaines, was grown on Mountview silt

Influence d'epandage de phosphogypse sur la croissance et l'absorption de cadmium et de radium des vegetaux (mais, ble et soja)

Many Fe sources have been tested to correct Fe chlorosis over the past 35 years, and no single Fe source has been found that is both effective and economical for most crops. Results from many Fe experiments are discussed. Variable results are reported from Fe source studies related to differences in Fe placement, rate, time of application, and weather and soil conditions. While controlling Fe chlorosis by developing more Fe‐efficient cultivars appears more promising, work to develop effective Fe fertilizers should continue. Perhaps the best method to control Fe chlorosis will be a combination of Fe‐efflcient cultivars with the best management practices, and reasonably effective Fe fertilizers.

Calcium silicate slag is a by‐product of the electric furnace reduction process for producing phosphoric acid from phosphate rock (PR). Since slag contains trace amounts of radium (Ra), and uranium (U) as contaminants from the PR, a greenhouse pot experiment was conducted to determine if plants absorb Ra from slag applied to soil. Slag at rates equivalent to 0 and 22 mt/ha was mixed with Mountview silt loam (Typic Paleudults) limed to pH 5.8 and 7.2. Three clippings each of fescue (Festuca arundinacea Schreb.), and Swiss chard (Beta vulgaris L.), and one harvest of wheat (Triticum aestivum L.) for grain and straw were grown on separate series of treated soil, and plant samples were analyzed for radioactivity due to Ra uptake. Samples of sugarcane (Saccharum officinarum L.) forage and extracted juice from field experiments in Florida testing this slag as a Si source also were analyzed for radioactivity. Dry forage yields of fescue and wheat were not affected by slag applications, but those of Swis...

Increased emphasis on biological fixation of N has resulted in increased soybean acreage and establishment of legumes for pastures in the Southeastern United States. Many of the soils in this region are acid and therefore may be marginal in available Mo, which is involved in symbiotic N fixation by legumes. A greenhouse experiment was conducted to determine relative response to applied Mo of two cultivars of soybeans and six species of forage legumes on acid and limed soil. Decatur sil (Rhodic Paleudult), at pH 5 and limed to pH 6 and 7, was fertilized with 0 and 2 ppm of Mo, P, K, and a micronutrient mixture minus Mo, inoculated with appropriate rhizobia, and seeded to legumes. Soybean tops were harvested after 6 weeks and three clippings of the forage legumes were made after 6, 9, and 13 weeks’ growth. Dry forage yields of all species increased with soil pH level without applied Mo. Soil application of Mo resulted in increased growth and uptake of N and Mo of most species at pH 5. Crop response...

Two coarsely ground air-dried municipal sewage sludges and a garbage compost were mixed with Hartsells fsl (limed to pH 5.5) rates of 15, 75, or 300 g/3 kg of soil in two greenhouse pot experiments. Fine ZnSO₄ and Na₂Cr₂O₇ were each mixed with soil limed to pH 5.5 to 7.0 at rates up to 1,400 ppm of Zn and 320 ppm of Cr, equivalent to rates applied in the organic wastes. Three successive crops of corn (Zea mays L.) were planted 0, 7, and 18 months after waste application. Corn forage yields were increased only in Crops 1 and 3 by compost applications but were not affected by sludge applications. Concentrations of Zn in the corn forage increased with application rate and Zn content of the three waste products. In contrast, Cr concentrations in the corn were not affected by the 0.05% to 1.36% Cr in the wastes. Concentrations of both Zn and Cr in the corn forage were much higher from ZnSO₄ and Na₂Cr₂O₇ from each waste at similar Zn and Cr rates and soil pH. Levels of 0.5N HCl-extractable Zn and Cr in the soil after each harvest increased with application rate of Zn and Cr in each organic waste and inorganic salt, but were not proportional to plant concentrations. Trivalent Cr as Cr₂(SO₄)₃ was less toxic to corn than hexavalent Cr as Na₂Cr₂O₇ at a rate of 80 ppm of Cr, while both sources were very toxic at 320 ppm. Toxicity resulted from ZnSO₄ in pH 5.5 soil at 240 ppm Zn and at 960 ppm in soil above pH 6.5. Results of these experiments suggest that Zn and Cr contained in municipal wastes applied at high rates are not toxic to corn even after relatively long periods in the soil. Reduced plant uptake of these heavy metals in organic waste was not due entirely to their liming effect on the soil.

Absorption of Zn by 14-day-old intact rice seedlings was studied in short-term uptake experiments. Severe retardation of Zn absorption by various metabolic inhibitors indicated that an active process prevails at Zn concentrations often found in soil solutions. Several cultivars all showed similar sensitivity to the metabolic inhibitor 2,4-dinitrophenol (DPN). At concentrations of 10−4 M, both FeCl2 and MnCl2 depressed Zn uptake in roots and translocation to shoots; uptake was depressed to a lesser extent with Ca. Although Mg reduced uptake by the roots, translocation to the shoots was enhanced. These results suggest that high solution concentrations of reduced Fe and Mn which develop in paddy culture may be related to Zn nutrition. This information could assist in predicting Zn deficiency and may explain correction of Zn deficiency by draining flooded rice fields.