Assessing of an irrigation and fertilization practice for improving rice production in the Taihu Lake region (China)

To address the global environmental and resource crisis, integrated, efficient, and sustainable agricultural practices need to be developed. We examined the effects of combining one of two irrigation methods (i.e., controlled irrigation and conventional flooding irrigation) with one of four different levels of nitrogen fertilizer applications (N; 300 (N0), 270 (N1), 240 (N2), and 180 kg N ha−1 (N3)) on grain yield, water use efficiency, and N production efficiency in rice. Additionally, we analyzed nitrogen leaching at different soil depths (20 cm and 80 cm) using lysimeters and N2O emission using a polyvinyl chloride chamber for each of the combinations examined. We found that the irrigation regime and level of N application significantly affected rice yield, and the rice yield in the controlled irrigation treatment was higher than that in the conventional flooding irrigation treatment by 2.12%–12.30%. Of all the treatments, combining controlled irrigation with the N1 fertilizer application resulted in the greatest grain yield. Loss of N was mainly caused by nitrate leaching. Controlled irrigation and reducing the amount of N fertilizer applied in the soil reduced N leaching, and increased the N production efficiency, while increasing N2O emission. Furthermore, water use efficiency was increased under controlled irrigation conditions, but reduced when less N fertilizer was applied. Thus, an agricultural regime that uses less water and lower amounts of N fertilizer than are currently being used in standard practices would likely increase yield and N production efficiency in soils, while reducing potential N leaching; however, the N2O emissions would also increase.