Soil Temperature and Sewage Sludge Effects on Metals in Crop Tissue and Soils
1979
Sheaffer, C. C. | Decker, A. M. | Chaney, R. L. | Douglass, L. W.
Effects of soil temperature and sewage sludge application on plant and soil Zn, Cu, Cd, Ni, and Pb levels, soil pH, and soil organic matter were determined in a field experiment in which corn (Zea mays L.) was grown for 2 years in a sandy Typic Hapludult soil amended with 0, 56, and 112 metric tons/ha of sewage sludge at the start of the experiment. Soil temperature regimes of 16, 27, 35°C, and ambient (x̄ = 22°C) were applied to sludge treatments from May to October each year. Following removal of corn at the conclusion of the 1975 growing season, oats (Avena sativa L.), wheat (Triticum aestivum L.), rye (Secale cereale L.), crimson clover (Trifolium incarnatum L.), and arrowleaf clover (Trifolium vesiculosum Savi) were grown until the following spring. Sewage sludge application resulted in significant increases in soil organic matter, pH, and DTPA extractable Zn, Cu, Cd, and Ni. Soil heating to 35°C significantly reduced soil pH for all sludge rates compared to 16°C and ambient (22°C) temperatures by the conclusion the experiment. This decrease was greatest for plots amended with 112 metric tons/ha sewage sludge and least for the check plots. Soil temperature had no effect on levels of soil organic matter or DTPA extractable metals. Extractable Zn, Cu, and Ni levels increased from the start to the conclusion of the experiment. Concentrations of Zn, Cu, Ni, and Cd were increased in corn, legume, and small grain tissue by sludge treatments. Corn seedling Zn and Cu concentrations exceeded that in ear leaves, stover, and grain; lowest metal concentrations were found in the corn grain. Increasing soil temperature did not consistently affect Cu, Ni, Cd, or Pb concentrations in corn tissue. Zinc concentrations in corn tissue generally increased as soil temperature rose, but exceptions did exist. No residual soil temperature effects were observed on metal concentrations in legumes or small grains.
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