Coupling Effects Of Controlled Release Urea And Subsoiling On Nitrogen And Water Utilization, Biomass Yield And Quality Of Maize

Field experiments in the experimental station of Shandong Agricultural University werecarried out from2009to2010. The experiment adopted a split-plot design. The main plotconsisted of two tillage methods, rototilling for stubble breaking (R) and subsoiling afterrototilling for stubble breaking (S). The deputy main plot used the maize varieties ofZhengdan958(Z) and Denghai3(D). The deputy plot focused on two urea types, normalurea (U) and controlled-release urea (C) with the amount of225kg N/hm2, with non-N (0) asthe control. Nitrogen and water use, photosynthetic characteristics, stem flow characteristics,and yield and quality of the biomass of maize were studied. The main findings are as follows:1. Nitrogen utilizationUnder the conditions of the same species and same farming methods, the application ofcontrolled-release urea increased nitrogen uptake of RC and SC,12.1%and8.5%higher thanRU and SU, respectively. With the same species and same urea types, subsoiling increased theN uptake of S0, SU, and SC,11%,10.1%, and6.5%, higher than R0, RU, and RC,respectively. And nitrogen uptake of D was3.1%higher than Z. The application of controlledrelease urea increased the NUEA of RC and SC,27.7%and19.6%higher than those of RU,and SU, respectively. The NUEA of SU and SC were8.5%and1.8%higher than those of RUand RC, respectively. And NUEA of D was8.6%higher than Z. NUEP and NPE withapplication of controlled release urea under subsoiling tillage was higher than that withapplication of conventional urea under rototilling for stubble breaking. Application ofnitrogen could increase the soil nitrate content in0~100cm soil layers compare with nonitrogen treatment. The slow release urea nitrogen increased the nitrogen absorption of maizeand reduced the residual nitrate in the soil. Subsoiling leaded to more nitrate leach to deeper soil layers, and reduce the efficiency of normal urea, while used release urea could reduce thenitrate leaching.2. Effects on Water Production EfficiencyThe nitrogen application significantly increased grain yield and water use efficiency ofmaize. The total water use efficiency was as follows: SC> RC> SU> RU> S0> R0. UnderZhengdan958, SC was2.36%,1.21%and3.25%higher than those of SU, RC and RU,respectively. Under Denghai3, SC was3.79%,2.15%and5.26%higher than those of SU, RCand RU, respectively. Under the same conditions, the total water use efficiency of Denghai3was significantly higher than that of Zhengdan958. The grain yields of SC, RC, SU and RUof Denghai3were4.85%,3.64%,4.21%and4.97%higher than those of Zhengdan958. Itshowed that controlled-release fertilizer could benefit the water management of time andspace, in the early stage it could saving water for the use in the late stage, which as a result,increase the production. Subsoiling can increase the use of soil water and increase the yield.Release urea matched with subsoiling could increase the precipitation and soil water useefficiency, and also obtain high yield.3. Effects on photosynthesis and snap flow of maizeThe release urea could significantly increase the photosynthetic rate and chlorophyllcontent. Subsoiling was benefit to maintain higher photosynthetic rate and chlorophyll contentafter flowering. The average advantage of the net photosynthetic rate and chlorophyll contentapplied the release urea at different growth stages were higher. SOD and POD activity andsoluble protein content of release urea were significantly higher, but MDA was lower contentthan those of normal urea. Subsoiling can significantly enhance thess effects. Thecontrolled-release urea and subsoiling can increase the antioxidant capacity of leaves, andextend the functional period of the leaves.The application of urea can significantly improve the average sap flow of maize. Beforeflowering, the stem flow of the treatment applied controlled release urea was significantlylower than that of normal urea. But from the flowering period, application of controlledrelease urea could increase the stem flow compared with that of normal urea. Stem flow undersubsoiling in the growth period of maize was significantly higher than rototilling for stubblebreaking.4. Effects on yield of maizeBefore flowering, the maize aboveground dry weight, leaf area index of release urea werelower than those of normal urea treatment, but after flowering those of release urea began tocatch up with the normal urea treatment. Grain yield and biomass yield under controlled-release urea at harvest were significantly higher than those of normal urea.Release urea could significantly increase maize N uptake, grain protein content, fat content,starch content, and protein yield. Subsoiling could significantly imcrease the protein yield,grain fat and starch content.5. Effects on straw composition of maizeIt can be seen, most of the chemical composition are affected significantly. Applied releaseurea could increase the crude protein content of maize stover. Controlled release urea andsubsoiling could increase the crude fat, ash, cellulose, and lignin contents of straw. And usingcontrolled release urea and subsoiling could increase the quality of straw.6. Better water-nitrogen mode for maizeThe application of coated urea and subsoiling could increase the yield by10.1%withhigher fertilizer use efficiency, and increase the quality of maize grain and straw.