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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...

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...

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

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...

This study related Cd-Zn concentrations in plants to levels of Cd and Zn in soil recovered by several extractants soon after application of Cd and Zn sources to soil. Cadmium nitrate and ZnSO/sub 4/ or Zn(C/sub 2/H/sub 3/O/sub 2/)/sub 2/ were mixed with a Zn-deficient Crowley silt loam soil, cropped with corn (Zea mays L.), and then cropped with Swiss chard (Beta vulgaris). Applied Cd significantly increased the Cd/Zn ratio in both crops, especially in Swiss chard, which accumulates heavy metals. A previously published sequential-extraction procedure was used to fractionate Cd and Zn in soil after the corn harvest. Results of statistical analyses showed the highest correlation between Cd uptake by each crop and the carbonate and sulfide fractions of Cd in soil. Including other Cd fractions resulted in only slightly higher R/sup 2/ values. Zinc uptake by each crop was best related to the organic fraction of Zn in soil, and including the other Zn fractions did not affect the relationship. These results show that Cd and Zn uptake by corn or Swiss chard was not related to similar chemical fractions of these elements in soil, and that the Cd/Zn ratio in plant tops was significantly affected by bothmore » Cd and Zn applications to soil.« less

Soil applications of inorganic Fe sources are generally not effective for crops unless rather high rates are applied. Since previous results had indicated that these sources may be effective if applied at lower rates with fluid polyphosphate fertilizers, several greenhouse pot tests were conducted. Dry matter production and Fe uptake by grain sorghum (Sorghum bicolor) were higher with FeEDDHA than with FeSO₄ or Fe₂₍SO₄)₃ applied to Epping sil (pH 7.5), a calcareous soil low in available Fe. There was very little crop response to either inorganic Fe source applied alone to the soil at rates up to 24 ppm Fe. However, both sources were somewhat effective when applied with fluid polyphosphate fertilizers at the same rates. Seed and foliar spray applications were not as effective as soil application, probably because the rate of Fe was limited by the application method. Without applied Zn, crop response to FeEDDHA was limited. However, Zn uptake by sorghum decreased while forage yields increased with FeEDDHA application rate, even though ZnSO₄ was also applied to the soil. Evidence for a marked Fe-Zn interaction in sorghum was shown on this soil. Application of ZnSO₄ to the no-Fe check treatment reduced growth and Fe uptake, while high Fe applications reduced Zn uptake in the presence or absence of applied Zn.

Fertilizers varying in level of H₂O-soluble Zn were prepared by combining fine ZnO and ZnSO₄ in various proportions and pressure-granulating the powders with ammonium nitrate, monoammonium phosphate, or ammonium polyphosphate. Forage yields and uptake of Zn by corn (Zea mays L.) grown on a P- and Zn-deficient soil in the greenhouse increased with the level of H₂O-soluble Zn in these macronutrient fertilizers. Additional crop response was slight to fertilizers with levels of H₂O-soluble Zn in excess of about 50% but this varied, depending upon the macronutrient carriers. However, the amounts of Zn extracted after cropping from untreated soils and soils initially receiving 12 mg of Zn per 3 kg of soil in a highly H₂O-soluble form were comparable. In a second experiment differential response of several corn hybrids to amount of P and Zn and level of Zn solubility in the fertilizers suggests that the test variety might influence the interpretation of the results from fertilizer evaluation studies. No relationship was found between P/Zn ratios in the corn forage and the seed. The P/Zn ratios in corn forage were not related to the response of corn to applied Zn.

Zinc oxide, ZnSO₄, and ZnS were tested as sources of Zn at rates of 1, 2, and 4 ppm Zn for two successive crops of corn (Zea mays) grown on Nolichucky sandy clay loam (pH 7.3). Each source was mixed throughout the soil as finely ground material, incorporated into granules of ammonium nitrate (AN) or ammonium polyphosphate (APP) by pressure granulation, and into granules of concentrated superphosphate (CSP) during the granulation stage of the manufacturing process. When mixed with the soil ZnO and ZnSO₄ were more effective than when incorporated with a macronutrient carrier. Both ZnO and ZnSO₄ were markedly superior to ZnS. Ammonium nitrate and APP were comparable carriers when ZnSO₄ was the source, but APP was superior to AN when ZnO was used. A higher concentration of Zn in the CSP granules resulted in poorer response to this carrier. Zinc oxide was pressure granulated with CSP, AN, APP, or Nolichucky soil to contain 0.5, 2.0, or 8.0% Zn. Soil granules and CSP were applied at 1, 2, and 4 ppm Zn while AN and APP were applied at 2 ppm only. Forage yields and Zn uptake varied inversely with concentration of Zn in all carriers.

Movement of Zn in Hartsells fine sandy loam (pH 5.2) from granules containing 2% Zn as ⁶⁵Zn labeled ZnSO₄ decreased in the order: ammonium nitrate (AN) > soil (no carrier) = concentrated superphosphate (CSP) > monoammonium phosphate (MAP) = triammonium pyrophosphate (TPP). In limed soil (pH 7.1) Zn movement was less from MAP than from all other carriers, and Zn movement from each carrier was less than that in acid soil. Zinc also moved further from MAP than TPP in other soil systems below pH 6.0, the same between pH 6.0 and 6.8, and less above this range. Most Zn movement from P carriers occurred during the first week, except in extremely acid soil. Carrier-Zn reactions affected the amount of Zn which moved out of the fertilizer granules, but soil-Zn reactions were also important in affecting Zn movement from the granule site. The recovery by various chemical extractants of Zn applied in granules of soil and in all macro-nutrient carriers to acid soils was similar. The amount of Zn recovered by 2N MgCl₂ from limed soil less than 0.5 cm from the granule varied with carrier after 1 week, but was similar for all carriers after 8 weeks. Uptake of Zn by corn (Zea mays L.) in a greenhouse pot experiment was greater from AN, but no clear relationship was evident with the P carriers.

Movement of Mn in acid Hartsells fsl (pH 5.1) from fertilizer granules containing 2% Mn as ⁵⁴Mn-labeled MnSO₄ was in the order: KCl = NH₄NO₃ [AN] > soil (no carrier) = concentrated superphosphate [CSP] = NH₄H₂PO₄ [MAP] ≫ (NH₄)₂HPO₄ [DAP] = (NH₄)₃HP₂O₇ [TPP] = ammonium polyphosphate [APP]. In limed Hartsells soil (pH 7.6) Mn movement was less from granules of all fertilizers, but the order remained the same. Movement of Mn applied in soil or MAP granules was greater in Spencer sil (pH 4.7) than in five other soils with higher pH levels. Application of Mn with MAP resulted in decreased Mn movement in all soils except Houghton muck. Little or no movement of Mn occurred when MnSO₄ was applied with TPP to any of these soils. Reduced movement may have been due to formation of reaction products of low solubility which reduced the concentration gradient of soluble Mn in the soil near the granule site. Percentage recoveries of applied Mn from the soil immediately adjacent to the granule sites by H₂O, neutral 1N NH₄OAc, and neutral 1N NH₄OAc containing 0.2% hydroquinone showed little difference for Mn applied alone or with granular AN, KCl, CSP, or MAP. However, the recoveries of Mn applied with DAP, APP, and TPP were lower, indicating lower solubility of Mn applied with these fertilizers. Recoveries of applied Mn also were less in soils with higher pH levels.