Effects of rotational tillage on soil water content and crop yield of spring maize system on Weibei dryland

Weibei dryland in Shaanxi Province belongs to the semi-humid drought climate in warm temperate zone, so drought is the biggest limiting factor for crop production in dryland. Shortage of precipitation and its uneven distribution in seasons are the main factors causing the low and unstable yields of winter wheat and spring maize in dryland. The Loess Plateau that is semi-humid and prone-to-drought, is a typical rain-fed agricultural region. Winter wheat and spring maize are main grain crops cultivated in this region. A long-term practice of applying single soil tillage measure in this area causes soil compaction, poor ability of retaining rainwater and improving water use efficiency. Many studies and practices have demonstrated that reasonable soil rotational tillage systems matching different crop rotation systems have played a very important role in maintaining sustainable development of farmland ecosystem, creating suitable environment (soil, nutrients, water, air, temperature) condition for crop growth and promoting crop yields. In order to investigate the effects of different rotational tillage systems on soil production performance in maize fields, the soil water storage, crop yield and water use efficiency as well as economic benefit were determined on the Loess Plateau of China, which would provide a theoretical basis for establishing a reasonable soil tillage system for the crop rotation system with certain fertilizing method on the semi-humid and prone-to-drought Loess Plateau. The aim of this experiment was to study the effects of different rotational tillage patterns on soil water conservation, grain yield and benefit increase in spring maize rotation region in Weibei highland. A six-year field experiment was carried out from 2007 to 2013 in Dryland Agricultural Research Station, Ganjing Town (35°33′ N; 110°08′ E; 900 m above sea level), Shaanxi Province. Three kinds of different rotational tillage systems in this experiment included continuous no-tillage (NT), no-tillage/subsoiling rotation (NT/ST), and continuous ploughing treatments (CT). The soil moisture during leisure and growth period of spring maize was measured, and the variation regularity of spring maize yield and water use efficiency was analyzed under 3 rotational tillage systems. Results revealed that: 1) Compared to continuous ploughing treatments, average water storage efficiency in 0-200cm soil layers of no tillage with subsoiling rotation and continuous no tillage in six-year winter fallow periods increased (P<0.05) 64.6% and 46.1%. In normal rainfall years, water storage efficiency of no tillage with subsoiling rotation was little higher than continuous no tillage, but it was no significant difference in drought years. 2) Compared to the CT treatment, the average soil water content in 0-200 cm soil layer for the NT/ST and NT treatment in maize growth period in 6 years increased by 9.7 and 2.1 mm, respectively, and the water storage efficiency in the fallow period increased by 0.7 and 0.5 (P<0.05) percentage point, respectively. 3) Compared to the CT treatment, the corn grain yield for the NT/ST and NT treatment in 6 years increased by 7.6% and 0.3% (P<0.05), respectively, the harvest index increased by 3.6 and 2.3 percentage point, respectively, and the water use efficiency increased by 18.6% and 5.8% (P<0.05), respectively. Among the 3 tillage treatments, the effects of soil water storage capacity, crop yield, harvest index and water use efficiency for the NT/ST and NT treatment were better than those for the CT treatment in the fallow period of winter, and the effects of soil moisture conservation and crop yield increment for the NT/ST treatment were the best, so the NT/ST treatment was the more suitable conservation tillage pattern in spring maize field of Weibei dryland.