Assessment of the effects of integrated rotation-tillage management on wheat productivity in the Loess Plateau region

The long-term use of conventional management practices coupled with the overapplication of synthetic fertilizers by smallholder family farms to meet food demand has negatively impacted the environment of farmland. Therefore, improved agronomic management practices are needed to enhance crop productivity. A 3-year (2016-2019) experiment was conducted to evaluate the effects of integrated rotation-tillage management [maize/soybean-wheat (MW/SW); chisel plow tillage (CPT), zero tillage (ZT), and plow tillage (PT)] on the farmland environment and wheat productivity in the Loess Plateau of China. The results indicated that SW and conservation tillage (CPT and ZT) increased soil nutrient levels and decreased soil pH and C/N values compared with conventional management practices (MW and PT); meanwhile, conservation tillage substantially increased soil moisture (SM, 3.56-16.06 %) compared with PT. Compared with MW and PT, SW and CPT increased aboveground biomass (0.26-4.45 % and 0.73-2.15 %, respectively) and nitrogen content (1.24-2.30 % and 0.26-2.73 %, respectively) during wheat development. Coincidentally, SW increased wheat actual yield (AY, 2.98 %) and maintained wheat theoretical yield (TY) and harvest index (HI) compared with MW; CPT increased wheat grain yield (AY, 6.72 %; TY, 3.28 %) and HI (2.26 %) compared with PT, while ZT caused significantly opposite results. CPT increased nitrogen fertilizer productivity (NfP, 3.28 %), nitrogen uptake efficiency (NupE, 1.19 %), and nitrogen use efficiency (NUE, 1.67 %) compared with PT regardless of crop rotations, while ZT significantly decreased NfP (9.69 %) and NupE (16.99 %) and increased NUE (8.18 %). Nevertheless, crop rotation did not substantially affect wheat nitrogen efficiency. Further correlation and partial least squares path modeling analysis revealed that elevated SM and nitrogen levels due to improved management practices had the potential to improve wheat productivity by regulating wheat growth characteristics. Overall, integrated SW-CPT management was more positive for improving farmland environment and enhancing wheat productivity in the Loess Plateau, which is suitable as a conservation strategy to adjust the cropping structure of smallholder family farms and promote sustainable agricultural development in arid and semiarid agricultural regions.