Abstract:
Abstract: Weibei highland of Shaanxi province belongs to warm temperate and semi-humid drought climate zone, so drought is the biggest limiting factor for crop production on dryland. Shortage of precipitation and uneven distribution in seasons are the main factors to cause the low and unstable yields of spring maize (Zea may L.) grown on dryland. A long-term practice of applying single soil tillage measures in this area causes soil compaction, poor ability of retaining rainwater and a low crop water use efficiency. In order to investigate the effects of different rotational tillage systems on soil production for spring corn fields, soil organic carbon sequestration, crop yields and water use efficiency (WUE) as well as economic benefits for different tillage system were determined on the Loess Platform of China. The research results could provide basis to establish a reasonable soil tillage system for a cop rotation system under a certain fertilizing method in the semi-humid and prone-to-drought Loess Platform. The objectives of this research were to study the effects of different rotational tillage patterns on soil bulk density, soil organic carbon sequestration, yield and economic benefit increase in spring maize rotation region in Weibei highland. A five-year field experiment was carried out from 2008 to 2012 in Dryland Agricultural Research Station, Ganjing Town (latitude 35°33′N; longitude 110°08′E; 900 m above sea level), Shaanxi province. There were six different rotational tillage systems in the study including no-tillage/sub-soiling rotation (NT?ST), sub-soiling/ continuous- tillage rotation (ST?CT), continuous tillage /no-tillage rotation (CT?NT), no-tillage/ no-tillage rotation (NT?NT), sub-soiling /sub-soiling rotation (ST?ST) and continuous tillage / continuous rotation (CT?CT). The data for spring corn grain yield, water use efficiency and economic benefits under different rotational tillage treatments were analyzed. Results showed that in the aspects of loosening soil, decrease of the frequency of tillage machine rolling and improving soil structure and lower bulk density, NT ? ST was the best among the six different rotational tillage systems, followed by ST ? ST (P > 0.05). In addition, soil organic carbon reserves increased by 6.6%-17.4% in average of 0-60 cm soil layer with the applying of six rotational tillage systems. NT ? NT tillage showed advantages in increasing the soil organic carbon sequestration. NT?ST rotation system changed the distribution of soil organic carbon characteristics in the top soil layer, and then made the soil nutrients distribute evenly. Through comprehensive evaluation and analysis of the grain yield, water use efficiency and economic benefit for spring corn of six rotational tillage systems in five years, NT?ST rotation tillage was the best with a yield of 9 338.8 kg/hm2, WUE of 22.6 kg/(hm2·mm) and economic benefit of 7 600.5 Yuan/hm2. The second was ST?CT. Increase of crop grain yield, water use efficiency and economic benefits of the NT?ST rotation tillage was respectively 3.7%-15.7%, 17.6%-45.8% and 10.1%-40.4% higher than other treatments(P > 0.05). The grain yield, water use efficiency and economic benefits of all five rotational tillage systems were higher than conventional tillage. The soil bulk density and soil organic carbon sequestration of NT?ST treatment were the best among six tillage treatments, as well as the crop yield, water use efficiency and crop yield increment. Therefore NT?ST was the most suitable conservation tillage practice for spring maize field on Weibei dryland, followed by ST?CT rotation tillage.