Studies On Aptimum Ratio Of Basal And Tillering N Fertilizer Under Different Fertility Soil In Rice

In china,nitrogen(N)utilization efficiency is only 30%-35%,only 20%in TaiHu lake where the overuse of N fertilizer is common,far lower than the word level.Most of nitrogen is lost by ammonia volatilization,leaching and runoff,directly or indirectly caused the pollution of underground water,eutrophication of rivers and lakes as well as global warming.How to coordinate the crop N demand with soil N supply,improve N utilization efficiency and keep high yield,and further reduce the risk of environmental pollution,is hot issue in N management.The formal studies were most focused on the amount of N rate and the ratio of early(basal and tillering fertilizer)and late fertilizer(panicle fertilizer),however few studies involved in the ratio of basal and tillering fertilizer on different fertility soil.Hence,this study aim to research the effect of different ratio of basal and tillering N on yield and yield components,N utilization and translocation,and population quality using field plot experiment and pot experiment.Five ratios of basal and tillerffing N fertilizer(R1(10:0)、R2(7:3)、R3(5:5)、R4(3:7)、R5(0:10))were set in field experiment,and three ratios of basal and tillering fertilizer R1(10:0)、R3(5:5)、R5(0:10))were set in pot experiment,which both using wuyunjing 23.The main results are as follows:1 Effect of different ratio of basal and tillering N fertilizer application on population quality of riceTwo year’s experiments proved that the effect of different ratio of basal and tillering fertilizer is different base on fertility soil.In the low fertility soil,with the increasing proportion of tillering N,leaf grows faster under the treatments of R3(5:5)and R4(3:7),tillering rate first increases then declined,while the peak of tiller numbers showed a decreasing trend.Under high fertility soil,leaf growth was slowed and tillering rate and the peak of tiller numbers were reduced with the increasing proportion of tillering N.Under high fertility soil conditions,tillering rate was significantly higher than that of the low fertility soil,and the time reaching the tillers peak was shortened.Comparing with others fertilization condition,tillering was delayed,the time reaching the tillers peak and peak number of tillers was reduced under the treatment without basal N(R5).It suggested that basal fertilizer is good for promoting tillering,increasing nitrogen use effence and protecting environment.2 Effect of different ratio of basal and tillering N fertilizer on rice yieldTwo year’s experiments showed that the effect of different ratio of basal and tillering N fertilizer is different base on soil fertility level.In the low fertility soil,the yield increased first and then decreased with the increasing ratio of tillering N,and was highest under the R3(5:5)treatment at the N rate of 300 kg hm-2 and R4(3:7)treatment at the N rate of 240 kg hm-2,and the difference with other treatments was significant.The higher yield was mainly attributed to the higher panicles.Under high soil fertility conditions,there are no significant difference with the increase of tillering N proportion,but the panicles showed a decreasing trend.The yield under high fertility soil was higher than that of low fertility soil with the same N rate or even 20%less N rate,which mainly due to the more panicles achieved under high fertility soil.3 Effect of different ratio of basal and tillering N fertilizer on N use efficienc y(NUE)The influences of different ratio of basal and tillering N fertilizer on NUE differed with the soil fertility:the total N accumulation and NUE of R3(5:5)treatment at the N rate of 300 kg hm-2 and R4(3:7)treatment at the N rate of 240 kg hm-2 was significantly higher than other treatments under low fertility soil condition.However,under high fertility soil conditions,NUE decreased with the increase of tillering N proportion,but the difference between treatments was not significant.Nitrogen translocation amount and transfer efficiency is not affected by the basal fertilizer management proportion,but related to soil fertility and amount of nitrogen fertilizer.4 Effect of different ratio of basal and tillering N fertilizer on the N dynamic of surface water and soilThe N concentration of sxurface water and soil are effected by different basal and tillering fertilizer management.The suitable ratio of basal and tillering N fertilizer(5:5 and 3:7)decreased the peak of N concentration and reduce the risk of nitrogen loss.Soil N concentration was increased by N fertilizer and is higher under high fertility soil condition than that under low soil fertility.The accumulative ammonia volatilization amount during the basal fertilizer period is decreasing with the increasing tillering N ratio,and was higher than the tillering fertilizer period.Under the same N rate,accumulative ammonia volatilization amount is higher under high fertility soil than low fertility soil.In order to promote the tillering,improve the NUE and reduce the N loss,N managing should fully take into account the differences of soil fertility,and coordinate the ratio of basal and tillering N.