Evaluating of phosphorus quantity/intensity parameters in soil with different systems of organic fertilising

Abstract

One of the refinement methods for estimating the parameters of phosphorus dynamics in soil is the construction of sorption isotherms in dependence on changes of exchangeable sorbed phosphorus in soil (ΔQ) and changes of phosphorus amount in soil solution (ΔI). Regression analysis allows to calculate equilibrium concentration (cequ) and phosphorus buffering capacity (BC). The mentioned analyses were realised on soils from the long-term field ex-periments of the Czech University of Life Sciences (CULS) in Prague and Crop Research Institute (CRI) in Ruzyně, Czech Republic. The influence of different organic fertilisers compared to the control (not amended) treatment was tested. For the evaluating of parameters, the root and logarithmic functions were used. The lowest cequ of the logarithmic function was always found on not amended treatment. Low amounts were found in the treatments amended with barley straw as well. The highest amounts were found in soil after potatoes cropping fertilised with farmyard manure (FYM). In the FYM variant fertilised with 70 kg P/ha, the cequ value reached 0.45 mg P/1. Both treatments fertilised with sewage sludge (720 kg P/ha and 240 kg P/ha) showed similar values of about 0.25 mg P/1. A different trend was found for the phosphorus buffering capacity (BC); this was the highest at the control treatment and at the treatment fertilised with straw. The lowest BC was observed in both soils after potatoes fertilised with FYM, where it reached 61 mg P/kg and 65 mg P/kg, respectively. Similar trends were found when evaluating root function.