| China has31%of the paddy fields in Asia and19%of paddy fields on Earth, more than any individual country in the world. China ranks among the world’s highest in terms of both total rice yield and unit area rice yield. This gives China substantial influence on the stability of world grain production. Irrigated rice in China accounts for nearly30%of global rice production and about30%of global nitrogen (N) consumption but the average N recovery efficiency (NRE) is just30%for it in China, indicating that nearly70%of N inputs are lost in ecosystems. Over-fertilization is the main reason for the low N efficiency in fertilization in China. In addition, inappropriate ratios of nitrogen, phosphorus, and potassium, incorrect timing of fertilization, and inadequate use of compost also the problems rice planting faced in China. Therefore, to develop a reasonable fertilization system will be beneficial to increase the rice production, the farmers’income and the fertilization use efficiency of crops. In this project, to understand the mechanism of increased grain yield and efficiency of modified fertilization practices on midseason rice in Hubei Province, we carried out three years field plot experiments using popular local rice cultivars in three representative rice-producing areas:Chibi, which is a hilly area in southeastern Hubei Province, Jingmen and Honghu, which are flat area in southeastern and center Hubei Province, respectively. Moreover, field trials were also conducted to test the effects of modified fertilization technologies on the grain yield and nitrogen use efficiency of mid-season rice at10field spots of Honghu, Hubei Province from2009-2011. The main research results are as follows:1Effect of the optimizing fertilization on the population quality and grain yield of midseason riceLocal popular midseason varieties of rice were used to find out key factors to increase grain yield and nitrogen use efficiency of midseason rice by modified fertilization technology in Hubei Province. Field trials with five N treatments and four replications were conducted synchronously at Jingmen County (2008-2009), Honghu County (2009-2011) and Chibi County (2008-2011) in Hubei Province, respectively. The results showed that the grain yield of MFP (Modified farmers’ fertilizer practice), SHY (Super high yield fertilizer practice) and MSP (Modified super high yield fertilizer practice) increased with varying degrees compared with FFP (Farmers’fertilizer practice), with yield increase rate2.0%-5.7%,1.4%-9.6%, 1.7%-13.6%, and the average income of them increased with742.4Yuan-hm"2,-243.4Yuan·hm"2,1222.4Yuan·hm-2, respectively. Compared with FFP, the nitrogen use efficiency of MFP and MSP increased substantially more than SHY. Further analysis showed that the panicles number of MFP, SHY and MSP were more than that of FFP, which could be attributed to that the modified fertilization technology could delay functional leaf senescence, maintain an optimum leaf area index (LAI), an optimized shoot biomass, a reasonable tiller number and a health population structure with high percentage of productive tiller.2Effect of optimizing fertilization on grain yield of rice and nitrogen use efficiency with different basic soil fertilityThree-year field trials were carried out to investigate the differences in the grain yield, soil N dependent rate (SNDR), N fertilization contribution rate (NCR) and the N fertilization efficiency of the popular midseason rice variety "Fengliangyouxiang1" among three treatments, including modified farmers’ fertilizer practice (MFP), farmers’fertilizer practice (FFP) and the control to study the effect of optimizing fertilization on grain yield of rice and nitrogen use efficiency in paddy fields with different basic soil fertility in Jianghan plain, China. The results showed that the grain yields of MFP were the highest among all the three different nitrogen fertilizer treatments in all the field spots with different basic soil fertilities. The grain yield of MFP increased by about6.9%and5.0%in the high soil fertility field (HSF) and the low soil fertility field (LSF) comparing with the treatment of FFP, respectively; and about17.3%and30.3%in HSF and LSF comparing with the control, respectively. Moreover, the N recovery efficiency (NRE), N agronomic efficiency (NAE) and partial factor productivity of applied N (PEPN) of MFP increased more greatly compared with that of FFP. The contribution of N fertilization on the grain yield in the LSF was significantly more than that in the HSF; however, low soil N dependent rate and good grain yield potential were observed in the LSF. Optimizing fertilization reduced the relative contribution of basic soil fertilities on the grain yield of rice and increased N fertilizer efficiency. |
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