Relationships among nutrient concentrations in corn (Zea mays L.) plants and extractable soil nutrients
McCoy, Dennis E.
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Research was conducted to determine relationships among nutrients in corn plants on soils with high yield potentials, to study the suitability of soil tests for estimation of micronutrient concentrations in plants, and to determine if B fertilization affects corn grain yields on selected Virginia soils. Fifty-three field sites were selected in 15 counties throughout Virginia for evaluation of nutrient interactions in plant tissue and micronutrient soil tests. The majority of the soils under study had high yield potentials as attested by the average corn grain yield of 8743 kg/ha. Boron application did not increase corn grain yield in field experiments on five soils. Concentrations of B, Ca, Cu, Fe, K, Mg, Mn, N, P, S, and Zn in the earleaf at the early silk growth stage were determined to assess the nutrient status of corn plants. The experimental data indicated that nutrient concentrations were too low to provide adequate amounts to corn plants on many sites. Corn plants on all of the sites were below the reported critical level of 0.26% S in the earleaf at the early silk growth stage. It was concluded that this critical level may be too high for S deficiency symptoms of corn plants. The negative relationship between concentrations of Ca and K in whole corn plants was attributed to high plant available K in soil which decreases Ca uptake by corn plants. A positive correlation between N and Zn in the sixth leaf tissue was attributed to higher Zn availability as N fertilization decreased soil pH levels. High amounts of soil P which had low soil Zn levels probably caused the inverse relationship between P and Zn in the sixth leaf tissue. Increases in availability of both Cu and Fe at lower pH levels may be responsible for the positive correlation between these micronutrients in the earleaf tissue. Multiple correlation analyses completed between ppm Mn in tissue and dilute HCl-H₂SO₄ extractable soil Mn, pH and organic matter content indicated coefficients of determinations of 0.993 and 0.990 for the 0-20.3- and 0-40.6-cm soil depths, respectively. These data suggest that the Mn test may be a good indicator of available soil Mn to corn plants. Hot water soluble B, soil pH and organic matter content did not give a good indication of B concentrations in corn plants. Extractable Zn by the EDTA-(NH₄)₂CO₃ procedure, soil pH and organic matter content accounted for 84.1% of the variation in Zn concentration in the earleaf of plants at the early silking stage.
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