Phosphorus balance in typical rainfield of black soil region in northeast China

This research aimed to evaluate the phosphorus balances at field level in black Soil Region in northeast China, which is one of three black soil regions in world and is one of the most important agricultural production regions in China. By using the soil nutrient balance method, the phosphorus balances were calculated for 11 fields representing four tillage practices [Conventional tillage system (TCT), No-tillage with straw covered system (TNT), Reduced tillage system (TRT) and Contour tillage system (TTT)], three vegetation recovery measures [Conventional tillage management (TCT), Vegetation recovery management (VVR) and Bare management (VB)], three land’s slope (3°, 5° and 7°) and three land’s length (20 m, 40 m and 60 m). Processes quantified included mineral fertilizer, organic matter and atmospheric deposition (inputs) and harvested products, surface runoff and soil erosion (outputs). Measurements of phosphorus flows were made in the 11 fields and the phosphorous balance of various experiment plots was assessed in a quantified manner in 2013. Moreover, the rainfall, the tillage practices, the flow output and sand output of experiment plots of different slope gradients and lengths and the relations between dissolved phosphorus and particulate phosphorus of 2013 were also analyzed. Results shows that VVR and VB are phosphorus deficiency and the others are phosphorus surplus. Rainfall are the main sources of phosphorus inputs for VVR and VB among the 11 experiment plots, while chemical fertilizers are the main sources for the other 9 zones. Crop harvest and soil erosion are the main outputs of phosphorus in the 11 zones, except in VVR and VB. This research provides support to the farmland nutrient management and the prevention and control of non-point source pollution within the region.