Effects of different rotational tillage patterns on soil physical properties and yield of winter wheat-spring maize rotation field in Weibei highland

To study the effects of different rotational tillage patterns on soil physical properties and crop yield under winter wheat- spring maize single-cropping rotation systems in Weibei highlands, a 7-year on-site conservation tillage experiment was conducted, which consisted of three rotational tillage and three continuous tillage treatments. The rotational tillage systems included NT/ST (yearly rotation between no-tillage and subsoiling), ST/CT (yearly rotation between subsoiling and conventional tillage) and CT/NT (yearly rotation between conventional tillage and no-tillage). Also the continuous tillage treatments included continuous no-tillage (NT/NT), continuous subsoiling (ST/ST) and continuous conventional tillage (CT/CT). The study was conducted in wheat-maize rotation fields in 2007 to 2014 in Heyang County, Shaanxi Province. Soil physical properties (e.g., bulk density, soil aggregates and soil moisture) and crop yield under different tillage treatments were measured in 2014. The results were as follows: 1) Soil bulk density, soil porosity and field water capacity were significantly impacted by the three rotational tillage patterns, and were best under NT/ST rotational tillage. Compared with CT/CT treatment, NT/ST rotational tillage treatment increased average field capacity in the 060 cm soil layer by 12.9%. 2) The properties of soil aggregates changed significantly under different rotational tillage treatments. The NT/ST treatment was the best with the highest macro-aggregate content (R_0.25), lowest rate of structure break-up, lowest unstable aggregate index (E_LT), highest water-stable aggregate mean weight diameter (MWD) and lowest fractal dimension (D) of mechanical-stable and water-stable aggregates. 3) In wheat growing period, average soil water storage in the 0200 cm soil layer and yield of wheat under NT/ST treatment were respectively 17.7 mm and 9.5% higher than CT/CT treatment. It was concluded that rotational tillage was conducive for improving soil physical structure. Also NT/ST rotational tillage was more favorable for large topsoil aggregates and soil structure stability, for improving soil water conservation and then for increasing crop yield. Thus NT/ST treatment was a more appropriate rotational tillage pattern for wheat-maize rotation fields in Weibei highlands.