Effects of rotational tillage practices on soil properties, winter wheat yields and water-use efficiency in semi-arid areas of north-west China

Soil degradation caused by continuous conventional tillage and long-term minimum and no-tillage in rain-fed areas of north-west China is known to reduce water-use efficiency and crop yield, because of the reduced soil porosity and decreased availability of soil water and nutrients. A 3-year field study was conducted to determine the effects of interval with no-tillage and subsoiling to overcome some of the tillage after crop harvesting on soil properties, crop yields and water-use efficiency in semi-arid areas of southern Ningxia. Three tillage treatments were tested: conventional tillage (CT) for 3 years as the control; no-tillage in year 1, subsoiling in year 2, and no-tillage in year 3 (NT/ST/NT); subsoiling in year 1, no-tillage in year 2, and subsoiling in year 3 (ST/NT/ST). The mean soil bulk density of tilth soil (0–40 cm) was significantly decreased by 3.5% and 6.2% compared with CT under NT/ST/NT and ST/NT/ST, respectively, and both treatments greatly improved total soil porosity. Rotational tillage could increase water-stable aggregates, soil organic matter and the available N and P content. Rotational tillage significantly in the 0–40 cm soil layers, with a higher effect under ST/NT/ST. Rotational tillage significantly improved soil water status, increased the amount of soil water stored during the summer fallow and wheat growing season compared with conventional tillage. Higher yield improvements coupled with greater water-use efficiency were achieved with NT/ST/NT and ST/NT/ST compared with CT, and these treatments increased wheat yields by 9.6% and 10.7%, along with water-use efficiency improvements of 7.2% and 7.7%, respectively. The results showed that the interval of no-tillage and subsoiling (rotational tillage) could improve soil physical and chemical properties, and thus significantly increase crop yields and water-use efficiency. This method could have important applications in the semi-arid areas of north-west China.