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[Effects of tillage alternation pattern with subsoiling on soil physical and chemical properties and spring maize yield in the Loess Plateau, China].

Straw mulching and subsoiling can protect soil and improve soil structure. However, long-term continuous subsoiling cannot continuously gain yield increasing and soil improvement. To realize continuous soil improvement and yield enhancement, a long-term experiment on subsoiling alternation patterns was carried out with spring maize continuous cropping in the Loess Plateau in 2007-2016. The subsoiling alternation patterns were no-tillage/conventional tillage/subsoiling (NT/CT/ST) and subsoiling/conventional tillage (ST/CT), with continuous subsoiling (ST) as control. We analyzed the effects of the different patterns on soil physical and chemical properties and maize yield. The results showed that, compared with the ST, the mechanical-stable aggregates (DR0.25) and water-stable aggregates (WR0.25) in NT/CT/ST were significantly increased by 9.2% and 21.9%, with the mean weight diameter (MWD) and geometrical mean diameter (GMD) being significantly increased. The WR0.25 in ST/CT was significantly increased by 11.9%. In 0-20 cm soil layer, soil bulk density in NT/CT/ST and ST/CT decreased by 7.0% and 11.5%, and soil porosity increased by 8.4% and 13.9%, respectively. In 20-40 cm soil layer, soil bulk density in ST/CT increased by 6.9%, and soil porosity decreased by 5.7%. In the NT/CT/ST, soil total nitrogen and organic matter contents significantly increased, but soil total phosphorus and total potassium contents reduced. The multi-year average grain yield of spring maize in NT/CT/ST was 10.2% higher than ST and 4.8% higher than ST/CT. The DR0.25, WR0.25, soil total nitrogen content and soil organic carbon content were all positively correlated with maize yield, indicating such changes faci-litated corn grain yield. Considering the effects on soil fertility and corn yield, the NT/CT/ST model was conducive to soil fertility, soil structural stability and higher maize yield.