Distribution of Phosphorus in Soils Irrigated with Municipal Waste-Water Effluent: A 5-Year Study

Latterell, J. J.; Dowdy, R. H.; Clapp, C. E.; Larson, W. E.; Linden, D. R.

Distribution of Phosphorus in Soils Irrigated with Municipal Waste-Water Effluent: A 5-Year Study

1982

Latterell, J. J. | Dowdy, R. H. | Clapp, C. E. | Larson, W. E. | Linden, D. R.

This 5-year field study of phosphate (PO₄) management was conducted on Waukegan silt loam (Typic Hapludoll) soil, which has a water table at about the 140- to 150-cm depth. The results of municipal waste-water irrigation, with annual application means of 0, 126, and 237 cm, indicates that in terms of PO₄ management, soils receiving comparable quantities of PO₄ from either waste water or mineral fertilizer (rates for good crop management) behaved in similar manner. Sharp increases in organic-P were found in the surface horizon of soil receiving effluent, while increased levels of available-P were observed to a depth of 60 cm in the high-treatment area (mean annual P addition of 160 kg/ha). Phosphate-adsorption studies, with the aid of the Langmuir equation, showed that the adsorption power of soil from the higher effluent application rates (237 cm/year) had been reduced. This was substantiated by higher P concentrations (0.01 vs. 0.07 mg/liter) observed in soil water at the 60-cm depth of the high-treatment areas. These observations were fitted into a simplified model that described the fate of effluent PO₄ applied to soil.

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