Abstract: 【Objective】 This paper was to explore the effects of cropping system in paddy field of red soil on the crops growth and soil nutrient change, and to provide with effective mode for cropping system reform under bad irrigation condition. 【Method】Through located field experiments, effects of different cropping systems of paddy soil including Pasture, Paddy-Upland Rotation, Upland Cropping et al on crop growth, yield and economic benefit was studied, and the change of soil organic matter and nutrient content was investigated.【Results】The results showed that crop yield and economic benefit were all increased as well as the ratio of output/ input according to the calculation with different crops’ price in present market. The yield under Paddy-Upland Rotation was increased by 51.3%, 31.7%, 16.3% respectively, comparing to that of control (Rice-Rice-Astragali), Pasture, Upland Cropping treatments. The greatest economic benefit occurred under Paddy-Upland Rotation, whose yield was increased by 34.7%、21.4% and 2.2% comparing to that of that of control (Rice-Rice- Astragali), Pasture, Upland Cropping treatments. Comparing to that of control, the economic benefit under Pasture, Upland Cropping treatments was increased by 11.0% and 31.8% respectively. The ratio of output/input under Pasture, Paddy-Upland Rotation, Upland Cropping treatments was enhanced 0.9, 0.6 and 0.3, repectively, when compared with that of control. It is good to plant pasture for improving soil fertility since soil organic matter, total nitrogen, total phosphorus and available phosphorus were all increased. However, the content of available nitrogen, total potassium, available potassium was reduced in certain degree for all the treatments, which indicated that it is necessary to increase nitrogen, especially potassium input under this field experiment fertilization level. 【Conclusion】Under the status of present paddy fertility of red soil regions, climate and crops cultivation and management, it is feasible to alter the cropping system of paddy fields with bad irrigation condition. In order to increase crops yield, to obtain considerable economic benefit, and to better regulate agricultural structure, it is suggested that to adopt such cropping system as Pasture and Paddy-Upland Rotation.

Key words: Cropping system, Crop growth, Economic benefit, Soil nutrient