| Winter wheat/summer maize rotation is the most important crop growing system inGuanzhong area where is the major area for grain production in Shaanxi Province. Fertilizerincreasing crop yield is out of question, but in recent years, over-use N fertilizer was verypopular, but P, K and organic fertilizer was not concerned very much, what's more, farmerswere used to apply fertilizer by their own ways in Guanzhong area, which cause benefitdescending, fertilizer efficiency lower, and environment pollution. The field experiment wascarried out in Yangling district to study the rules of N, P, K nutrients uptake and accumulationunder the winter wheat/summer maize rotation system. Meanwhile, the effects of differentfertilizer rate on crop yield, culms, shoot dry matter accumulation, fertilizer efficiency, soilinorganic N accumulation and N balance were studied. The objective of this study was toprovide a theoretical basis for scientific fertilizer application and technical supports forsteadily increasing grain yield. The main results were showed as follow:1. Effect of different fertilizer rates on yield, nutrient uptake and soil nitrate nitrogenaccumulation of winter wheatOne-year field experiment from2009to2010was conducted to study yield, nutrientuptake, soil nitrate nitrogen accumulation and N fertilizer use efficiency of winter wheatunder different fertilizer rates. The results showed that NPK combined applicationsignificantly increased grain yield, the yield were6427~6527kg/hm~2, improved8.5%~10.2%compared with farmer's conventinal fertilization, but there was no significant differencebetween the two NPK combined application treatments. The grain yield of applying organicmanure treatment was7225kg/hm~2and22.0%higher than that of farmer's conventinalfertilization. There are significant difference on uptake amount of nutrient between differenttreatments, compared with farmer's conventinal fertilization treatment, uptake amount of N, Pand K of NPK combined application treatments improved11.6%~19.5%,16.5%~17.7%and21.7%~27.6%respectively, that of applying organic manure treatment improved36.4%,38.3%and43.3%respectively. Soil nitrate nitrogen accumulation (0~100cm soil profile) wasincreased with fertilizer rate improved at harvest stage, that of apply fertilizer treatments were 126.2~149.7kg/hm~2and50.8%~78.9%higher than CK treatment. NPK combined applicationsignificantly increased N fertilizer use efficiency, which was41.3%~49.3%, and that ofapplying organic manure treatment was59.6%. In conclusion, the recommend N, P2O5, K2Oapplication rate of winter wheat were150,97.5,75kg/hm~2respectively accompanied by basaldressing15000kg/hm~2organic manure and50%of N fertilizer was top dressing at jointingstage under this experiment condition (target yield is7000kg/hm~2).2. Effect of different fertilizer rates on yield, nutrient uptake and accumulation ofsummer maizeOne field experiment in2010was conducted to study yield, shoot nutrients and drymatter accumulation at various growth stages and N fertilizer use efficiency of summer maizeunder different fertilizer rates. The results showed that NPK combined with organic manureapplication significantly increased grain yield, N, P, K concentration in plant, nutrient and drymatter accumulation at various growth stages, but there was no significant difference betweenthe three NPK combined with organic manure application treatments, the yield were8802~9020kg/hm~2, improved12.5%~15.3%compared with farmer's conventinal fertilization,N fertilizer use efficiency of farmer's conventinal fertilization treatment was11.8%, but thatof NPK combined with organic manure application treatments was16.1%~17.4%. The phasefrom floret to filling was the highest phase of the proportion of N, P, K and dry matteraccumulation accounted for the largest accumulation, the proportions were38.3%~47.5%,51.4%~65.6%,36.9%~42.2%and60.4%~64.1%respectively. In conclusion, the recommendN, P2O5, K2O application rate of summer maize were300,90,60kg/hm~2respectivelyaccompanied by basal dressing15000kg/hm~2organic manure and40%of N fertilizer was topdressing at floret stage under this experiment condition (target yield is9000kg/hm~2).3. Effect of different fertilizer levels on population dynamics and grain yield formationof winter wheatOne-year field experiment from2010to2011was conducted to study yield, culms, shootnutrients and dry matter accumulation at various growth stages and fertilizer use efficiency ofwinter wheat under different fertilizer levels. The results showed that wheat grain yieldincreased significantly above middle application rate of NPK, but the difference of grain yieldwas not significant between H and M treatments, so that middle application rate of NPK wasmore reasonable which yield was6927kg/hm~2and13.4%higher than that of FP treatment.The grain yield of H+OM treatment was10444kg/hm~2and71.0%higher than that of FPtreatment. The culm number, shoot nutrients and dry matter accumulation amount wasincreased with application rate improved at various growth stages. The spike number of M, Hand H+OM treatments were539.2,599.2and891.7×104/hm~2respectively, which the difference was significant among the three treatments. The total shoot dry matteraccumulation amount of M, H and H+OM treatments were15254,15601and26026kg/hm~2respectively, which showed that H+OM treatment can increase total shoot dry matteraccumulation amount significantly over the other two treatments. Balanced fertilization of N,P, K could increase fertilizer use efficiency, the RENand REPof M treatment were highest ofL, M and H treatments, which were44.5%and24.7%, the RENand REPof H+OM treatmentwere highest of all treatments, which were71.8%and40.2%. In conclusion, the recommendN, P2O5, K2O application rate of winter wheat were180,120,75kg/hm~2respectivelyaccompanied by basal dressing20000kg/hm~2organic manure and50%of N fertilizer was topdressing at jointing stage under this experiment condition (target yield is9000kg/hm~2).4. Effect of different N fertilizer rates on yield, nutrient uptake and soil N balance ofsummer maizeOne field experiment in2011was conducted to study yield, nutrient uptake andaccumulation, N fertilizer use efficiency, soil inorganic N accumulation and N balance ofsummer maize under different N fertilizer rates. The results showed that grain yield increasedsignificantly under the N fertilizer rate were between180to270kg/hm~2, the yield were6730~7001kg/hm~2, improved6.3%~10.6%compared with N0treatment, but there was nosignificant difference between N180, N225and N270treatments The yield was not increasingwith amount of N fertilizer application increased when the rate was over-use, even the yieldwould decrease, and N, P and K accumulation at harvest stage had similar trend. N fertilizeruse efficiency of different N application treatments were only12.2%~25.6%. Applying Nfertilizer significantly increased soil nitrate nitrogen content (60~200cm soil profile), and thecontent was increased with soil depth increased, and the content of180~200cm soil profilewas11.5~15.8mg/kg. At harvest stage, apparent N losses amount of N fertilizer and amount ofresidual Nmin(0~200cm soil profile) were increased with rate of N fertilizer applicationincreased, the losses amount was34.4~179.5kg/hm~2and the amount residual Nminwas246.1~324.6kg/hm~2. In conclusion, the recommend N fertilizer rate of summer maize was135~180kg/hm~2under this experiment condition. |
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