Phosphorus Availability and Balance with Long-Term Sewage Sludge and Nitrogen Fertilization in Chernozem Soil under Maize Monoculture.

A continuous long-term field experiment with maize monoculture was conducted to evaluate the P availability and balance, DM yield, P uptake, and P sorption parameters in chernozem soil after 27 years. A total of 2 doses of nitrogen (120 and 240 kg ha -1 ) were applied as mineral nitrogen (N 120 and N 240 ) and sewage sludge (SS 120 and SS 240 ) and compared with unfertilized control (Con). The aboveground biomass (DM) yields significantly increased in the order of Con < SS 120 < SS 240 < N 120 < N 240 treatments and the maximum P uptake was recorded for both N 240 and SS 240 (25.1 kg P ha -1 ) according to the nutrient application gradient. The N 120 and N 240 treatments positively influenced the DM yield but negatively influenced the P balance (-648 and -678 kg P ha -1 27 years -1 ), gradually bringing a risk of P deficiency in the soil. On the other hand, applications of SS 120 and SS 240 positively influenced the P availability and pseudototal (P AR ) content in the soil, which resulted in a buildup of legacy P or an increase in P saturation greater than the environmental threshold value. Aluminum was found to be a major controlling sorption factor for P in our chernozem soil.