Increasing N-use Efficiency Of Rice In No-tillage Scattering Management

No-tillage scattering is a simplified cultivation method for simplifying land preparation and crop establishment tasks. Extension of no-tillage scattering can achieve great social and economic benefits. However, fertilizer only can apply on the soil surface under no-tillage conditions, which can result in large fertilizer loss and environmental problems. Increasing N-use efficiency through improving fertilizer management practices is critical to achieving a better environment. Currently, there is limited information available on increasing N-use efficiency in no-tillage scattering rice. Therefore, we conducted several field experiments. In2012, field experiments were conducted at Huaiji, Guangdong Province with Wuyou308as test cultivar and Liuyang, Hunan Province with Shentaiyou9712and Xinyou9113as test cultivars in late season to compare coating urea (B) with common urea (A) used as one-time fertilization. In2013, a field experiment was conducted at Liuyang, Hunan Province with Lingliangyou104and Zhongjiazao17as tested cultivars in early season to compare coating urea (B), sulfur-carrying urea (C), KSFBJ-4-carrying urea (D) and common urea (A) used as one-time fertilization, and to compare three urea types (B, C and D) under two management practices (T1:total N application rate was150kg hm-2, which was split applied as basal fertilizer, tillering fertilizer and panicle fertilizer at a ratio of5:2:3; T2:application of5g N/seedling tray1-4h before scattering, total N application rate was120kg hm-2, which was split applied as tillering fertilizer at a rate of75kg N hm"2and panicle fertilizer); field experiments were conducted at Liuyang, Hunan Province with Lingliangyou104as tested cultivar in early season and at Changsha, Hunan Province with Xiangwanxian12as tested cultivar in late season to determine the effect of fertilizer-attached seedlings on rice performance. By analyzing the yield performance, dry matter accumulation characteristics and N-use efficiency, we obtained the following results:(1) Under no-tillage scattering conditions, coating urea had no significant effect on improving rice yield, dry matter accumulation and N-use efficiency.(2) Under one-time fertilization conditions, N applied as tillering fertilizer (its grain yield was0.65-1.47t hm-2lower than the highest grain yield of the same cultivar in the same region) was more efficient than as basal(it was2.58-3.10t hm-2lower) for improving rice yield.(3) Improving N management practices could largely reduce N input (15%-45%) without sacrificing rice yield.(4) Application5g N/seedling tray1-4hours before scattering had no damage risk on rice seedlings.Accordingly, we proposed a N management strategy for no-tillage scattering rice: reducing total N application rate by disapplying basal fertilizer, adoption of fertilizer-attached seedlings to offset the potential negative effect of disapplying basal fertilizer, targeting application rates of tillering and panicle fertilizers according to cultivar growth characteristics during early growing period (if growth during early growth period is slow, more tillering fertilizer is applied; if growth during early growth period is fast, more panicle fertilizer is applied).