Effects of irrigation methods on soil environment and rice yield in paddy ecosystems

On the basis of the long-term field experiments in Taoyuan Experimental Station of Agriculture Ecosystem-CERN, Hunan Province, effects of irrigation methods on the soil physic and chemical properties and productivity of paddy were simulated and analyzed. The four treatments included rain-fed paddy field (RI), basin irrigation (BI), normal irrigation (NI), controlled moist irrigation (CI). The results showed that in the red soil region of south China, BI led a low soil bulk density and a high water storage capacity, which were favorable for the accumulation of soil organic matter (SOC) and nitrogen (N). SOC in surface layer (0-20 cm) of BI was higher than RI and CI by 7.0% and 6.1%, respectively, and soil N was 10.8% and 8.8%. The experiment also showed that, the soil surface temperature of RI was 0.3-0.5℃ higher than CI during days of rice growing. Because of the rich rainfall resources in this area, the differences yield of the early rice among treatments could be attributed to the changes of soil nutrients induced by different irrigation methods. And water became the limited factor for the high yield of late rice. Among the four irrigation methods, BI might be the best model for obtaining high rice yield.