Land Application of Chemically Treated Sewage Sludge: II. Effects on Plant and Soil Phosphorus, Potassium, Calcium, and Magnesium and Soil pH

Anaerobically digested sewage sludge resulting from treatment of sewage with Ca(OH)2, Al2(SO4)3, or FeCl, for phosphorus precipitation were applied at rates supplying up to 1,600 kg N/ha each year to corn (Zea mays L.) and bromegrass (Bromus inermis Leyess). Treatments with NH4NO3 supplying up to 400 kg N/ha were included. Soil PH was increased by Ca‐sludge and reduced slightly by Fe‐sludge application. Phosphorus and magnesium concentrations in corn grain and stover were unaffected by treatment. Phosphorus concentration in bromegrass, and NaHCO3‐soluble soil P, were increased by Ca‐sludge and, to a lesser extent, by Fe‐sludge additions. The Ca‐sludge treatments resulted in a lower K concentration in corn stover and seedlings than either Al‐ or Fe‐sludge treatments. Increasing sludge or NH4NO3 application reduced K concentration in bromegrass. Both sludge and NH4NO3 applications decreased ammonium acetate‐extractable soil K in the bromegrass experiment. Sludge application had no effect on Ca concentration in corn grain or stover from Conestoga loam and Caledon loamy sand, but increased it in corn seedlings and stover from Oneida clay loam. Calcium in bromegrass was increased by sludge treatment with the Ca‐sludge having the greatest effect. Magnesium in bromegrass was increased by sludge and by NH4NO3 applications. The Ca‐sludge decreased Mg extracted by ammonium acetate from the loam and clay loam soils but not from the loamy sand.