Anaerobically digested sewage sludge at 11.2, 33.6, and 67.2 metric tons/ha and farm manure at 6.7, 20.2, and 40.4 metric tons/ ha rates were applied annually for two consecutive years to an acid Byler loam soil (Typic Fragiudalf) cropped to corn (Zea mays L.) and sorghum (Sorghum vulgare L.). A recommended NPK check was included. Available P (1% (NH 4 ) 2 SO 4 in 0.05N H 2 SO 4 -extractable) levels in the soil were determined after crop harvest in the ensuing spring, each of the two years. Levels of available P in the organic amended plots did not increase significantly in the surface soil (0 to 20cm) layer the first year. Some movement of P into the subsurface soil (20 to 40cm) layer was observed, however. Significant buildup of available P due to the organic amendments was ob-611

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