Effects of Dense Planting with Less Basal N Fertilization on Rice Yield, N Use Efficiency and Greenhouse Gas Emissions

Rice cropping innovations for high yield with high N use efficiency (NUE) and low greenhouse gas (GHG) emissions are significant in ensuring food security and coping with climate change. The objective of this study was to investigate the comprehensive effects of dense planting with less basal N application (DR) on rice yield, NUE and GHG emissions. Field experiments were conducted at three sites in China. Shenyang, Danyang and Jinxian representing annual single rice cropping system, wheat-rice cropping system and double rice cropping system, respectively. Four planting densities with 25, 50, 75 and 100% higher each time correspondingly with about 25, 50, 75 and 100% less in basal N rate (i.e., DR1, DR2, DR3 and DR4 correspondingly) relative to traditional cropping for high yield (CK). Across three tested sites, the DR1 mode showed a large potential of NUE enhancement by 19.6% and GHG emissions mitigation by 12.2% at area-and yield-scaled with similar rice yield compared to the CK. However, further increase in planting density and decrease in basal N application caused a significant reduction in rice yield with a large increase in GHG emissions. Our results will provide important reference to rice cropping innovations for the integrated goals of food security, environmental health and climate change mitigation in China (C) 2015 Friends Science Publishers