Combined tillage: A management strategy to improve rainfed maize tolerance to extreme events in northwestern China

Climate warming has increased the frequency of droughts and excessive precipitation, adversely affecting crop growth, particularly under traditional intensive tillage. No-till improves crop tolerance to extreme events by reducing soil evaporation and improving soil structural stability to enhance soil water storage capacity and crop resistance, but long-term mono-no-till cakes the soil, reducing crop yield. Combining intensive tillage with no-till can compensate for some deficiencies arising from conventional tillage or single no-till. A three-year field experiment was conducted in wet (2020) and normal (2019 and 2021, where a drought event occurred in 2021) years to study the effect of tillage practices on summer maize productivity under different precipitation types. Treatments included conventional tillage (CT), no-tillage (NT), ridge cultivation with no-tillage (RNT), and conventional tillage of winter wheat combined with no-tillage of summer maize (NC). Compared with NT, NC and RNT significantly reduced soil bulk density and increased soil porosity in the 0–20 cm soil layer. Compared with CT, NC and RNT significantly improved aggregate stability, NC increased available soil water storage by 19.7% in the dry season (P < 0.05), and NC and RNT significantly reduced lodging rate in the rainy season. Over the three years, NC and RNT maintained higher maize yields (NC: 10.3 t ha–1 and RNT: 10.0 t ha–1) than CT (9.2 t ha–1), and NC had significantly higher yield stability than CT. Meanwhile, NC and RNT had higher precipitation use efficiency (PUE; NC: 21.2 kg ha–1 mm–1, RNT: 20.7 kg ha–1 mm–1) than NT (20.1 kg ha–1 mm–1) or CT (19.1 kg ha–1 mm–1). In terms of combined productivity, NC and RNT provide a more suitable soil environment for crop growth and maintain higher yield than NT and CT. NC rotation is recommended as the optimal tillage system for sustainable crop production under semi - arid agricultural conditions. RNT can be extended to areas prone to flooding with abundant rainfall. These results offer a benchmark for future studies on regional maize production under climate change.