Long-term effects of optimized fertilization, tillage and crop rotation on soil fertility, crop yield and economic profit on the Loess Plateau

Soil nutrient deficiency is the primary factor limiting sustainable development of agriculture on the Loess Plateau. Crop yield and soil fertility can be improved using measures such as optimized fertilization, conser-vation tillage, and crop rotation. A long-term study was conducted between 2007 and 2019 to evaluate the effects of optimized agriculture management on crop yield, economic profit and soil fertility. The following nine treatments were used: CK, local farmers' practice; F, optimization of fertilization; S, optimization of tillage method; R, optimization of cropping system; FS, optimization of fertilization and tillage method; FR, optimi-zation of fertilization and cropping system; SR, optimization of tillage method and cropping system; FSR, opti-mization of fertilization, tillage method and cropping system; HFSR, reduced half fertilization based on FSR. The results showed that grain yield was the highest (6129 kg ha-1) with FSR, and economic profit was increased by 3515 yuan ha-1, relative to CK. Moreover, FSR reduced soil bulk density and improved soil porosity and water storage. For soil nutrients, relative to CK, soil organic carbon (SOC) and soil available potassium (SAK) stock were 22 % and 46 %, respectively, in the 0-60 cm layer, and 7 % and 16 % higher in the 60-200 cm layer, while residual soil nitrate-N was lower in the 60-200 cm under FSR. The key soil nutrient factors affecting yield and economic profit were SOC (positive correlation) at 0-60 cm layer and nitrate-N (negative correlation) at 60-200 cm layer. HFSR had the highest fertilizer partial productivity, improved grain yield and economic profit relative to CK, which is based on sacrificing original soil fertility and resulted in soil degeneration. These findings provide important guidance for selecting effective integrated agricultural strategies to improve grain yield, profit, and soil fertility.