Effects of cropping system change for paddy field with double harvest rice on the crops growth and soil nutrient

صينى. 探讨红壤地区双季稻田改制对作物生长及土壤养分变化的影响，为灌溉条件较差稻田种植制度改革提供有效模式。利用田间定位试验方法，研究了双季稻田改种牧草、水旱轮作及旱作等模式对作物生长、产量和经济效益的影响，并分析了土壤有机质和养分含量的变化。按各处理生产产品的市场价格进行折算，稻田改制可增加产值、提高产投比。各处理比较，以水旱轮作产值最高，分别比对照、牧草和旱作处理增加34.7%、21.4%和2.2%，且牧草和旱作处理也分别较对照增加了11.0%和31.8%；牧草、水旱轮作和旱作处理产投比值分别比对照高0.9、0.6和0.3。种植牧草对提高土壤有机质和全氮、全磷及速效磷含量有较好效果，但各处理土壤碱解氮、全钾、速效钾的含量均有一定幅度下降，说明在本研究的施肥水平下，有必要增加氮素、特别是钾素养分的投入。在当前红壤地区双季稻田肥力状况、气候及作物栽培管理条件下，对灌溉条件较差的稻田进行改制是可行的，其中，种植牧草或实行水旱轮作对提高经济效益、提升土壤肥力有较好效果。

إنجليزي. This paper aimed to determine the effects of cropping system change for red soil paddy field with double harvest rice on crops growth and soil nutrient. It also aimed to provide with optimum pattern for cropping system reform under bad irrigation condition. Through located field experiments, effects on crops growth, yield and economic benefit were studied under different cropping systems. These included systems from paddy field with double harvest rice to pasture, paddy-upland rotation, upland cropping et al, and the change of related soil organic matter and nutrient content under various cultivation systems was also investigated. The results proved that economic benefit and the ratio of output to input were all increased in terms of the market price for the crops under various treatments. The greatest economic benefit occurred in the treatment of paddy-upland rotation, and the corresponding economic benefit was increased by 34.7%, 21.4% and 2.2% in comparison with equivalent of control (rice-rice-astragali), pasture, upland cropping treatments. The economic benefit from pasture, upland cultivation treatments was increased by 11.0% and 31.8% respectively compared to the equivalent of control. The ratio of output to input under pasture, paddy-upland rotation, upland cropping treatments was enhanced 0.9, 0.6 and 0.3, respectively, in comparison with that of control. It is acceptable to plant pasture grass for improving soil fertility since the contents of soil organic matter, total nitrogen, total phosphorus and available phosphorus were all enhanced obviously. However, the concentrations of soil available nitrogen, total potassium, available potassium was somewhat reduced for all the treatments, suggesting that increasing the input of nitrogen, particularly potassium, was necessary under present fertilization level. Based on the condition of the fertility, climate, cultivation and management in red soil paddy with double harvest rice regions, it is feasible to change the cultivation system of paddy fields with bad irrigation conditions. In particular, such cultivation systems as Pasture and Paddy-Upland Rotation were worth adopting for better economic benefit and improvement of soil fertility in the purpose region.