Bicarbonate‐Extractable Phosphorus in Fresh and Composted Dairy Manures

Abstract

Abstract The availability of the P from manure and from KH 2 PO 4 was estimated by extraction with NaHCO 3 following incubation in soils for 15, 30, and 45 days. In two alkaline sandy soils the availability of the P from manures was equal to that from KH 2 PO 4 . The availability of manure P relative to P from KH 2 PO 4 increased as the pH increased and as the sand content increased, i.e., as the clay plus silt increased. The relative availability of the manure P increased in some soils as the time of incubation increased.