Nutrient Management On Rice And Wheat Yield Formation And The Related Physiological Research

In recent years,the problems of food demand and security were more and more severe,especially for the continuously decreased agriculture land area and increased human population.And it become necessary to solve this contradiction through improving crop yield.Rice and wheat are the two most important staple food of China,and rice-wheat rotation system is an important part of China's agricultural structure.As the major agriculture province in China,Jiangsu is one of the most important commodity grain production bases in china.However,due to the blind pursuit of high yield of local farmers,a series of problems were existed during the process of fertilization,and this has also brought some negative impact on crops and the environment.Meanwhile,it doesn't meet the ideas of green agriculture,sustainable agriculture and some other requirements.So we can improve the farmers' fertilization habits,which aims to achieve the synchronization of nutrient supply and crop demand,and finally improve the fertilizer use efficient.Our experiment was conducted from the wheat season of 2015 to the rice season of 2016,in a long-term experiments site located in DongMei Farm of Nandu town,Liyang city,Jiangsu Province.Two experiments were conducted here,one is the experiment of optimization of nitrogen fertilizer and 4 treatments were settled with non-nitrogen fertilizer(PK),Farmer Fertilizer practice(FFP),Optimize treatment(OPT)and Super high yield(SHY);the second experiment is organic replacement,with 8 treatments settled for both wheat and rice,including non-nitrogen fertilizer(PK),Farmer Fertilizer practice(FFP),Pig manure 20%(PM20%),Chicken manure 20%(CHM20%),Cow manure 20%(CM20%),Pig manure 100%(PM 100%),Chicken manure 100%(CHM100%),Cow manure 100%(CM 100%).This study aimed to investigate the effects of nitrogen fertilizer management on yield and yield composition,N absorption and utilization efficiency,temperature and water content during grain filling stage,which could provide theoretical basis for the high yield and high efficiency fertilization in rice-wheat rotation system.The main findings are listed below:1.Under rice-wheat rotation system,we can improve nitrogen use efficiency and keep crop yield through reducing nitrogen fertilizer application and changing nitrogen management.In the rice season,the nitrogen fertilizer application under farmers fertilization treatment could reach 350 kg/hm2,while it was 240 kg/hm2 for optimize fertilization treatment and 270 kg/hm2 for super high yield treatment.Compared with FFP,the crop yield under OPT condition was not decreased,with significant reduced N fertilizer application,whilst the SHY treatment could increase crop yield.For the experiment of organic replacement,20%nitrogen fertilizer was replaced based on the OPT.Compared with FFP,the 20%replacement by pig manure and chicken manure have no significantly influence on crop yield while a little decrease was observed under cow manure replacement.However,the 100%replacement of nitrogen fertilizer by organic manure would resulted in significantly decreased crop yield.In the wheat season,the applied nitrogen amount is same under FFP and SHY(240 kg/hm2),while it was 200 kg/hm2 for OPT.The yield formation under SHY was significantly higher than that under FFP while no significant difference was observed between FFP and OPT.We illustrated that,FFP could achieve a better yield than 20%organic replacement,with the lowest yield exhibited after 100%replacement.And basically,the effect of pig manure was better than the chicken manure,and both were better than cow manure.The OPT changed the yield components of rice and wheat,with increased seed setting rate and grain weight of rice and grain number per panicle and grain weight of wheat,and this eventually achieved the high production and efficiency.2.The nitrogen optimized management resulted in increased nitrogen use efficiency in rice-wheat rotation system.Compared to FFP,OPT and SHY have a significantly higher nitrogen agronomy efficiency,nitrogen recovery efficiency and nitrogen partial factor productivity.After a organic fertilizer replacement,nitrogen use efficiency was further improved.The change of nitrogen fertilizer application increased nitrogen application in the later growth stage,which caused the accumulation of nitrogen and this could prevent crop premature senescence and provide sufficient nitrogen for crop reproduction.3.Meanwhile,after the nitrogen optimized management,the grain filling rate of rice and wheat were changed,which further increased the grouting ratio and dry matter accumulation in the late stage.Significant positive correlation between crop yield and the temperature difference between panicle and leaf was observed in both wheat and rice,and the effect of nitrogen on leaf temperature was higher than that of panicle temperature,which resulted in the difference between crop panicle temperature difference and leaf temperature difference.In summary,through the changes of nitrogen fertilizer application,fertilization time and organic replacement,the nitrogen use efficiency was highly improved,and the nitrogen supply could meet the demand of crop growth and development.And then we can establish the nitrogen management mode of soil-environment-crop trinity,which finally achieved high yield and high fertilizer efficiency.