Study On The Efficient Regulation And Application Techniques Of Nitrogen Fertilizer In Crop Field Incorporated With Straw Returning

With the combination of incubation test and field experiments, this paper studied theeffects of nitrogen regulation agents on nitrogen transformation, crop yields and nitrogenuse efficiency in wheat/maize ration system incorporated with straw returning in the twotypical ecological region, i.e, piedmont plain area of Taihang Mountain and Heilonggangarea in Hebei province. Moreover, the characteristics of decomposition and nutrientsrelease of wheat/maize straw were investigated. The major results were illustrated asfollows:(1) Urease inhibitors (UIa and UIb) played the role of inhibition on urea hydrolysis ina short time. The synergistic effects of UIa or UIbwith nitrification inhibitor (NI) onnitrogen transformation had been found, and that of UIb was better than that of UIa.(2) The results of laboratory incubation test showed that soil nitrification intensity wassignificantly inhibited by NI whether straw returning or not. While the better inhibitoryeffect was observed under the straw returning condition. The main reason was thestimulation effects of straw on the number and the activity of soil microbial communities,which was proved by the higher soil respiration rate, significantly increased the amount ofmicrobial immobilized nitrogen. The application of NI could significantly inhibit soilnitrification potential and nitrate reductase activity, but the soil total microbial communityor activity were not affected, which further explained the specificity of NI.(3) During the whole growth period of wheat or maize in the wheat-maize rotationsystem, the accumulative decomposition rate of maize and wheat straw was around50%and32%~46%, respectively. The accumulative release rate of K from wheat or maizestraw was fastest, that of P was the secondary one, and the third one was N. Theaccumulative released amount of N, P, K was11.36~23.62kg/hm2,32.68~40.62kg/hm2and114.18~120.38kg/hm2for winter wheat, and13.78~22.18kg/hm2,4.37~12.94kg/hm2and92.74~98.14kg/hm2for summer maize, respectively.(4) The results of field experiments in different ecological region showed that thewheat yield was not affected by reducing the amount of nitrogen fertilizer appropriately onthe basis of farmer conventional fertilization. The maize yield was significantly increasedin treatment with comnbination of nitrogen fertilizer and nitrogen regulation agents.Compared with the control treated with urea, wheat yield and maize yield in treatmentswith the combination of UI and NI were increased by23.1%~26.1%and5.2%~12.3%, respectively. And the partial factor productivity, apparent N recovery efficiency, nitrogenuptake efficiency and agronomic efficiency were increased by18.3%~24.6%,104.3%~225.8%,100.2%~208.3%and18.1%~21.0%for wheat, and increased by5.5%~8.0%,15.7%~30.1%,22.0%~27.8%and12.0%~22.1%for maize, respectively.(5) The nitrogen input/output balance in wheat-maize rotation system in Gaochengcounty was analyzed. The results indicated that reducing nitrogen fertilizer inputsappropriately and adding urease/nitrification inhibitors could reduce the nitrogen balancesurplus amount and the nitrogen balance surplus rate significantly, which contributed toreducing the waste of nitrogen resource and alleviating environmental pollution.