A Complete Measurement for Phosphorus Loss with Phosphorus-Based Cattle Manure Application from a Clay Loam Soil.

Changes in manure application from nitrogen-based to phosphorus (P)-based approach can alter P dynamics in soil and its fate from soil to surface water, and the later has to be quantified to improve P management efficiency and to program long-term nutriment management planning. We investigated the effects of P-based application of liquid (LCM) and solid cattle manure (SCM), in comparison with chemical fertilizer (CF), on soil P loss in both surface runoff and tile drainage in a clay loam soil under corn-soybean rotation over a four-year period.  Each of the three sources of P was applied at 50 kg P ha^-1 to the corn phase of the rotation. Both surface and sub-surface flows were continuously monitored and sampled on a year-round base using the state-of-art auto-systems. Water samples were analyzed for dissolved reactive P (DRP) and particulate P (PP). Concentration of DRP with SCM was generally higher than those with CF and LCM addition in surface runoff, while in tile drainage water it was largely identical amongst the three P sources. Concentrations of PP in both surface runoff and tile drainage water followed the order of SCM>CF>LCM. As a result, total soil P loss (TPL) in both surface runoff and tile drainage with LCM remained unchanged, although the DRP loss was 16% less, relative to CF. In contrast, addition of SCM decreased the TPL by 19% through the reduction in PP loss, although it increased the DRP loss by 54%, compared with CF. The calculated values for manure P source coefficients (PSC) were 0.84 and 1.54 based on DRP loss, and 0.99 and 0.81 based on TPL, for LCM and SCM, respectively. The PSC values can be applied to improve the prediction efficiency of site P index for risk assessment of soil P loss and to develop manure application BMPs.