Phosphorus Mobility in a Soil with Long Term Manure Application

Abstract

The objective of this experiment was to determine the movement of different forms of phosphorus (P) in a clay loam soil with 33 years of manure application at the rate of 0, 30, 60 and 120 Mg ha^-1yr^-1. Soil samples were taken from 3 soil layers and subjected to leaching in packed soil column. Leachate was analyzed for total (P_t), inorganic (P_i) and organic P (P_o). Inorganic P accounted for about 70% of leachate P_t. About 50% of P_t in leachate was lost within the first 5 pore-volume (PV). While 2% of soil total P was lost in 20 PV of leachate from the control soil, 5-7% was lost from the manure amended soil. The amount of P lost in the leachate increased with the rate of manure application but decreased with soil depth. This column leaching study showed that P could be lost through leaching especially at high rate of manure application. Irrigation activity enhanced in situ movement of P down the soil profile.