Study On The Reasonable Amount Of Nitrogen Fertilizer Applied To Rice-wheat System In Central Jiangsu

The experiment was carried out in the experiment base of Jiangdu Xiao Ji Town,Jiangsu Province,in the year of 2014-2016.Through the study on the rice and wheat of different fertilizer combinations of nitrogen fertilizer of rice and wheat reasonable anniversary amount of nitrogen fertilizer.Rice test materials are conventional japonica variety Wuyunjing 24,Nanjing 9108,hybrid rice Yongyou 2640,Set the six nitrogen levels ON(0kg/667m2),14N(14kg/667m2),18N(18kg/667m2),22N(22kg/667m2),26N(26kg/667m2),and 30N(30kg/667m2),are provided.Planting method is Seedling transplanting machine;Based on the test of rice,wheat in Yangmai 16 as test materials.Set the five nitrogen level ON(0kg/667m2),14N(14kg/667m2),18N(18kg/667m2),22N(22kg/667m2),26N(26kg/667m2),planting patterns for drilling machine.The effects of nitrogen application rate on yield formation and nitrogen uptake and utilization of rice and wheat were studied systematically,which provided the basis for the rational application of nitrogen in rice and wheat in two seasons.The main results are as follows:1.The yield of rice varieties showed a trend of increasing first and then decreasing with the increase of nitrogen application rate,yield reached the highest when the amount of nitrogen applied to 22N,the Wuyunjing 24,Nanjing 9108 and Yongyou 2640 were respectively 700,650 and 750kg per mu(1mu=667m2=1/15ha),but there was no significant difference with the amount of nitrogen application 18N;with the increase of the rate of nitrogen application,the earing percentage decreased with the increase of nitrogen application rate;tiller number increase in early with the increasing of nitrogen,in the later period,the amount of nitrogen fertilizer increased and then decreased with the increase of the nitrogen application rate.Dry matter accumulation of rice transplanting to heading stage increased with the increase of N application rate,in the heading to maturity,the amount of nitrogen increased and then decreased with the increase of nitrogen application,and then decreased to the maximum value of 22N.The population growth rate of rice also showed the same trend as dry matter accumulation.2.The nitrogen content of rice varieties was the highest in the jointing stage,the higher in the heading stage and the lowest in the maturity stage.The amournt of nitrogen uptake increased with the increase of the amount of nitrogen applied at the stage of transplanting to jointing stage and heading stage;during heading to maturity,the amount of N uptake increased first and then decreased with the increase of N application rate,all varieties had the highest nitrogen uptake at 22N level,the utilization rate of Nanjing 9108 at the 18N level was the highest,the utilization rate of the other two varieties in the 22N level was the highest;agronomic efficiency,partial productivity and physiological utilization decreased with the increase of nitrogen application rate.after more than 18N,it decreased significantly;one hundred kilograms grain nitrogen demand increases with the increase of nitrogen.3.With the increase of the amount of nitrogen application,wheat yield increased first and then decreased,in 18N,the highest yield of mu,reaching 400kg,the amount of nitrogen application in the first cropping rice had a certain effect on the yield of wheat,when the amount of nitrogen fertilizer was ON and 14N in wheat season,the wheat yield increased with the increase of the amount of nitrogen applied in the previous rice cropping season;the application in the previous rice cropping season of nitrogen fertilizer in wheat season still had a certain effect on the fertilizer application rate of 18N,a slight increase in yield of 22N was increased from ON to with the increase of nitrogen content in the previous cropping rice cropping season,the amount of nitrogen applied to rice in the rice season increased,but the yield of wheat increased slightly;wheat yield increased to 22N,wheat yield did not increase but decrease,the amount of nitrogen fertilizer not only did not increase the yield of rice,and even played a role in reducing the yield of rice.The amount of nitrogen fertilizer not only did not increase the yield of rice,and even played a role in reducing the yield of rice.Therefore,from the point of view of production,the annual reasonable amount of nitrogen fertilizer for rice and wheat is 36-40N.Wheat tillers decrease with the increase of nitrogen fertilizer amount,under the ON and 14N levels,the spike rate also decreased with the increase of the amount of nitrogen application in rice.Wheat dry matter accumulation also increased first and then decreased with the increase of nitrogen application rate,under the ON and 14N levels,it increased with the increase of nitrogen content in rice,after reaching 18N and beyond,the impact is not significant,the overall trend is similar to the yield.4.The highest nitrogen content in wheat was the highest in the jointing stage,the second in the heading stage and the lowest in the maturity stage.In the three period,the whole plant nitrogen content showed an increasing trend with the increase of the amount of nitrogen application.When wheat was in ON and 14N,the nitrogen application in rice also had a certain effect on it,with the increase of the amount of nitrogen application in rice,the nitrogen content of wheat increased slightly;however,under the high nitrogen treatment,the effect of the amount of nitrogen application in rice was not significant.The total nitrogen uptake of wheat increased with the increase of N application rate,in the amount of nitrogen fertilizer reached and exceeded 18N,the increase in the amount of absorption is not significant.Nitrogen uptake and utilization rate of wheat showed a trend of first increasing and then decreasing with the increase of N application rate,when the amount of nitrogen application in wheat was 18N,it reached the highest,and then decreased obviously;the amount of nitrogen applied to rice also had some influence on it,when the amount of nitrogen application was 14N,the rate of nitrogen uptake and utilization increased significantly with the increase of the amount of nitrogen application in rice,after arriving at 18N,the utilization rate can be increased slightly,then the effect is not significant.Wheat agronomic efficiency also increased first and then decreased with the increase of nitrogen application rate,and the trend was consistent with the nitrogen utilization rate.The partial productivity and physiological utilization rate of wheat decreased with the increase of nitrogen application rate;the N-requirement for 100 kg grain of wheat showed with the nitrogen decreases and then increases again.