Abstract
Abstract: The semi-humid and prone-to-drought Loess Platform is a typical rain fed agricultural region, in which the planting system is mostly one harvest a year or one harvest two years. Winter wheat and spring maize are main grain crops cultivated in this region. A long-term practice of applying single soil tillage measures in this area causes soil compaction, poor ability of retaining rainwater and providing nutrition. Many studies and practices have demonstrated that reasonable soil rotational tillage systems matching different crop rotation cropping systems played a very important role in maintaining the 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 wheat-maize fields, the soil bulk density, soil porosity, soil nutrients contents, water storages, crop yields and water use efficiency (WUE) as well as economic benefits were determined on the Loess Platform of China, which will provide a theoretical 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. A six-year field experiment was carried out from 2007 to 2013 in Dryland Agricultural Research Station, Ganjing Town (latitude 35°33′N; longitude 110°08′E; 900 m above sea level), Shaanxi province. Six kinds of different rotational tillage systems of this experiment included no-tillage/sub-soiling rotation (NT/ST), sub-soiling/ploughing rotation (ST/PT) and ploughing/no-tillage rotation (PT/NT), no-tillage/ploughing/sub-soiling rotation (NT/PT/ST), no-tillage/no-tillage/sub-soiling rotation (NT/NT/ST), ploughing/ploughing/sub-soiling rotation (PT/PT/ST). The continuous no-tillage (CK1), continuous sub-soiling (CK2) and continuous ploughing (CK3) for six years were used as control. Results revealed that, 1) ST/PT was the best to decrease soil bulk density, increase soil porosity, improve soil structure and permeability in six kinds of rotational tillage systems, followed by PT/PT/ST; 2) Comparing with other rotational tillage systems, NT/ST and ST/PT increased the soil organic matter and total nitrogen content significantly in 0-40 cm soil layer, ST/PT and PT/PT/ST increased the available nutrient content apparently; 3) Comparing with other rotational tillage systems, NT/ST and NT/NT/ST got higher soil water storage before sowing, and the same results was founded after harvesting; 4) Considering the overall effects of grain yields, WUE, and economic benefits, ST/PT was the highest, followed by NT/ST, thirdly NT/PT/ST, NT/NT/ST was the lowest. ST/PT increased grain yields by 5.4%-14.1%, WUE by 1.9%-14.1%, economic benefits by 8.2%-22.6%, compared with other rotational tillage systems. NT/ST increased grain yields by 2.8%-8.2%, WUE by 5.7%-11.5%, economic benefits by 5.1%-13.3%, compared with other four rotational tillage systems. In conclusion, appropriate rotational tillage systems are beneficial for protecting soil environment, improving soil structure, retaining soil water, increasing crop yield and economic benefits. sub-soiling/ploughing rotation system (ST/PT) had good production performance in reducing soil bulk density, improving soil structure, promoting soil increasing water storages and soil nutrients contents, promoting crop yields and WUE, which is more suitable soil rotational tillage system in winter wheat and spring maize rotation fields. No-tillage/sub-soiling rotation system (NT/ST) could increase rainwater infiltration, protect soil, and enhance water reserving and soil moisture keeping, and its crop yields and economic benefits were only inferior to ST/PT. Hence, NT/ST was also a good soil rotational tillage system in this region. Considering the local conditions, ST/PT could be recommended as suitable soil tillage patterns to match the "one crop one year" crop rotation system, followed by NT/ST. These two systems can be employed to achieve better production performance on the basis of the specific situation.
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