稻田轮作系统的生态学分析

针对目前稻田单一化的连作耕作制度对农田环境造成的不利因素，根据5a田间定位试验，从土壤理化性状、作物产量变化、病虫害发生发展规律、能流及养分平衡状况等角度对稻田连作耕作制度和轮作系统进行生态学分析。结果表明，与连作耕作制度相比较，在试验设计范围内，稻田轮作系统明显改善了土壤的理化性状，使得土壤随着耕种年限增加，容重下降，而孔隙度增加，固相比率下降，气相比率上升，气液比值增大，土壤通透性大大增强，有效阻止土壤次生潜育化和土壤酸化，提高土壤pH值；改变了植株病原菌寄生，增强了植株的抵抗能力，对作物病、虫、草害产生了一定的抑制作用。同时，稻田轮作系统的总初级生产力、光能利用率、辅助能利用率分别比连作系统高17．47％、9．87％和5．0％。N、P、K的养分利用率也同样明显高于连作系统。提出了合理轮作的优化模式和复种模式。

ECOLOGICAL ANALYSIS OF CROP ROTATION SYSTEMS IN PADDY FIELD

Aimed at the unfavorable impact of mono-cropping cultivation on farmland environment, in paddy field, a fiveyear field experiment was carried out. Ecological analysis in the experiment was conducted to compare crop rotation with monocropping cultivation in soil physical and chemical properties, yield, incidence of crop diseases and pests, energy flow and nutrient balance. The results show that the former significantly improved soil physical and chemical properties and yield by 384.8%, 226.2% and 3.0%, respectively. Moreover, crop rotation not only altered the environment for pathogen bacteria, but also built up plant resistance to diseases and pest, and suppressed crop diseases, insects, and weeds, etc. and increased the overall initiative productivity, light energy use rate and auxiliary energy use rate by 17.47%, 9.87% and 5.0%, respectively, N, P and K use rate as well. Therefore, reasonable optimized muhi-crop rotation systems are presented in the paper.