Cross-ridge tillage decreases nitrogen and phosphorus losses from sloping farmlands in southern hilly regions of China

Losses of nutrients, water and soil from sloping farmlands have a large potential to contribute to water eutrophication and land degradation. However, few long-term and multi-site measurements are available to assess the magnitude of effects of cross-ridge tillage on surface runoff and nitrogen (N) and phosphorus (P) losses from sloping farmlands. Field experiments were conducted under natural rainfall conditions for six to seven years across four experimental sites in southern China. Each site-year experiment consisted of three management practices: downslope ridge without fertilizer as control (CK), downslope tillage with fertilizer (DF), and cross-ridge with fertilizer (CF). Results indicated that compared to the downslope tillage practice, cross-ridge tillage reduced the average annual runoff by 6.11% to 64.2%. Compared with DF, CF significantly decreased total N (TN) and total P (TP) losses by 11.3% to 69.7% and 15.9%- to 63.5%, respectively (P