【目的】合理施用氮肥不仅会提高肥料利用率,还会降低氮素面源污染的风险。通过2年田间肥料定位试验,研究北疆灰漠土区不同氮肥用量下,土壤无机氮积累量、氮素平衡和玉米产量间的相互关系,为氮肥合理施用提供依据。【方法】研究采用肥料田间定位试验,小区试验于20112012年开展,设计6个氮肥( N)用量水平：0、225、300、375、450、600 kg/hm2,分别以N0、N225、N300、N375、N450、N600表示,其中300 kg/hm2为当地玉米农田氮肥推荐用量,磷肥(P2O5)施用量为75 kg/hm2,钾肥(K2O)施用量为37.5 kg/hm2。【结果】1)施用氮肥增加了土壤硝态氮和铵态氮残留量,硝态氮主要残留于0-60 cm土层,铵态氮主要分布在0-20 cm土层深度。2011年试验中,土壤无机氮残留量随氮肥用量增加而显著增加,与对照相比,施氮处理无机氮残留量增幅为12%102%,与施氮量呈指数增长关系。2012年氮肥用量对土壤无机氮残留量的影响与2011年相似。2)施氮量<225 kg/hm2时,0-100 cm土层深度土壤无机氮积累量降低,表现为负积累效应,N0和N225处理下2012年土壤无机氮积累量分别较2011年降低165%和170%；施氮量高于300 kg/hm2时,土壤无机氮积累量显著增加,表现为富集现象,其中,N375、N450和N600处理下2012年土壤无机氮积累量分别较2011年增加17%、388%、170%。土壤无机氮积累量与施氮量显著呈二次抛物线关系,2011年回归方程为y=0.0001x2+0.1013x-22.537(R2=0.9288),无机氮无积累时施氮量为187 kg/hm2；2012年为y =0.0003x2+0.1417x -52.78(R2=0.9583),无机氮无积累时施氮量为245 kg/hm2。土壤氮素表观损失量和氮素盈余量的增加幅度随氮肥用量增加而显著加大。3)氮肥投入可提高玉米产量,产量与施氮量呈显著的二次抛物线或线性加平台的关系,施氮量高于300 kg/hm2时,玉米产量与最高产量差异不显著；产量与无机氮积累量呈二次抛物线形关系,当土壤无机氮达到平衡时,玉米产量显著低于最高产量,当玉米产量达到最大时,土壤无机氮有一定积累。氮肥利用率则随氮肥用量增加呈指数关系显著降低。施氮量270 kg/hm2为产量与氮肥利用率的交点,施氮量340 kg/hm2是土壤无机氮残留量与氮肥利用率的交点。【结论】利用产量效应、环境效应与肥料效应函数的交点确定氮肥投入阈值,是较为优化的方法。合理的氮肥投入不仅能获得玉米高产,降低氮素面源污染风险,还能获得较高的氮肥利用率。因此,施氮量260340 kg/hm2为本研究区玉米高产与环境友好的氮肥投入阈值。
【目的】閤理施用氮肥不僅會提高肥料利用率,還會降低氮素麵源汙染的風險。通過2年田間肥料定位試驗,研究北疆灰漠土區不同氮肥用量下,土壤無機氮積纍量、氮素平衡和玉米產量間的相互關繫,為氮肥閤理施用提供依據。【方法】研究採用肥料田間定位試驗,小區試驗于20112012年開展,設計6箇氮肥( N)用量水平：0、225、300、375、450、600 kg/hm2,分彆以N0、N225、N300、N375、N450、N600錶示,其中300 kg/hm2為噹地玉米農田氮肥推薦用量,燐肥(P2O5)施用量為75 kg/hm2,鉀肥(K2O)施用量為37.5 kg/hm2。【結果】1)施用氮肥增加瞭土壤硝態氮和銨態氮殘留量,硝態氮主要殘留于0-60 cm土層,銨態氮主要分佈在0-20 cm土層深度。2011年試驗中,土壤無機氮殘留量隨氮肥用量增加而顯著增加,與對照相比,施氮處理無機氮殘留量增幅為12%102%,與施氮量呈指數增長關繫。2012年氮肥用量對土壤無機氮殘留量的影響與2011年相似。2)施氮量<225 kg/hm2時,0-100 cm土層深度土壤無機氮積纍量降低,錶現為負積纍效應,N0和N225處理下2012年土壤無機氮積纍量分彆較2011年降低165%和170%；施氮量高于300 kg/hm2時,土壤無機氮積纍量顯著增加,錶現為富集現象,其中,N375、N450和N600處理下2012年土壤無機氮積纍量分彆較2011年增加17%、388%、170%。土壤無機氮積纍量與施氮量顯著呈二次拋物線關繫,2011年迴歸方程為y=0.0001x2+0.1013x-22.537(R2=0.9288),無機氮無積纍時施氮量為187 kg/hm2；2012年為y =0.0003x2+0.1417x -52.78(R2=0.9583),無機氮無積纍時施氮量為245 kg/hm2。土壤氮素錶觀損失量和氮素盈餘量的增加幅度隨氮肥用量增加而顯著加大。3)氮肥投入可提高玉米產量,產量與施氮量呈顯著的二次拋物線或線性加平檯的關繫,施氮量高于300 kg/hm2時,玉米產量與最高產量差異不顯著；產量與無機氮積纍量呈二次拋物線形關繫,噹土壤無機氮達到平衡時,玉米產量顯著低于最高產量,噹玉米產量達到最大時,土壤無機氮有一定積纍。氮肥利用率則隨氮肥用量增加呈指數關繫顯著降低。施氮量270 kg/hm2為產量與氮肥利用率的交點,施氮量340 kg/hm2是土壤無機氮殘留量與氮肥利用率的交點。【結論】利用產量效應、環境效應與肥料效應函數的交點確定氮肥投入閾值,是較為優化的方法。閤理的氮肥投入不僅能穫得玉米高產,降低氮素麵源汙染風險,還能穫得較高的氮肥利用率。因此,施氮量260340 kg/hm2為本研究區玉米高產與環境友好的氮肥投入閾值。
【목적】합리시용담비불부회제고비료이용솔,환회강저담소면원오염적풍험。통과2년전간비료정위시험,연구북강회막토구불동담비용량하,토양무궤담적루량、담소평형화옥미산량간적상호관계,위담비합리시용제공의거。【방법】연구채용비료전간정위시험,소구시험우20112012년개전,설계6개담비( N)용량수평：0、225、300、375、450、600 kg/hm2,분별이N0、N225、N300、N375、N450、N600표시,기중300 kg/hm2위당지옥미농전담비추천용량,린비(P2O5)시용량위75 kg/hm2,갑비(K2O)시용량위37.5 kg/hm2。【결과】1)시용담비증가료토양초태담화안태담잔류량,초태담주요잔류우0-60 cm토층,안태담주요분포재0-20 cm토층심도。2011년시험중,토양무궤담잔류량수담비용량증가이현저증가,여대조상비,시담처리무궤담잔류량증폭위12%102%,여시담량정지수증장관계。2012년담비용량대토양무궤담잔류량적영향여2011년상사。2)시담량<225 kg/hm2시,0-100 cm토층심도토양무궤담적루량강저,표현위부적루효응,N0화N225처리하2012년토양무궤담적루량분별교2011년강저165%화170%；시담량고우300 kg/hm2시,토양무궤담적루량현저증가,표현위부집현상,기중,N375、N450화N600처리하2012년토양무궤담적루량분별교2011년증가17%、388%、170%。토양무궤담적루량여시담량현저정이차포물선관계,2011년회귀방정위y=0.0001x2+0.1013x-22.537(R2=0.9288),무궤담무적루시시담량위187 kg/hm2；2012년위y =0.0003x2+0.1417x -52.78(R2=0.9583),무궤담무적루시시담량위245 kg/hm2。토양담소표관손실량화담소영여량적증가폭도수담비용량증가이현저가대。3)담비투입가제고옥미산량,산량여시담량정현저적이차포물선혹선성가평태적관계,시담량고우300 kg/hm2시,옥미산량여최고산량차이불현저；산량여무궤담적루량정이차포물선형관계,당토양무궤담체도평형시,옥미산량현저저우최고산량,당옥미산량체도최대시,토양무궤담유일정적루。담비이용솔칙수담비용량증가정지수관계현저강저。시담량270 kg/hm2위산량여담비이용솔적교점,시담량340 kg/hm2시토양무궤담잔류량여담비이용솔적교점。【결론】이용산량효응、배경효응여비료효응함수적교점학정담비투입역치,시교위우화적방법。합리적담비투입불부능획득옥미고산,강저담소면원오염풍험,환능획득교고적담비이용솔。인차,시담량260340 kg/hm2위본연구구옥미고산여배경우호적담비투입역치。
[Objectives]For reasonable application of nitrogen fertilizer and low risk of pollution from nitrogen fertilizer, accumulation of inorganic nitrogen and nitrogen balance under different N fertilizer application rates were investigated in gray desert soil. Correlation between accumulation of inorganic nitrogen in soils and yield of maize was also evaluated by conducting field experiments in 2011 and 2012, respectively. [Methods]A field experiment was conduced in grey desert soil from 2011 to 2012. There were six treatments with N application levels of 0 , 225 , 300, 375, 450 and 600 kg/ha, accordingly, noted as N0, N225, N300, N375, N450 and N600, respectively. The local recommended N application rate was 300 kg/ha, P2 O5 75 kg/ha, K2 O 37. 5 kg/ha. [Results]The results show that the residual contents of NO3--N and NH4+-N in soils are enhanced by the N application. The residual NO3--N is mainly distributed in 0-60 cm soil depth and the residual NH4+-N in 0-20 cm soil depth. The residual nitrogen amounts are increased significantly with the increase of N application rate, and the increments are ranged from 12% to 102% when the N application rates are from 0 kg/ha to 225 kg/ha, and to 600 kg/ha in 2011. There are significantly exponential correlations between the residual nitrogen in soils and N application rates. The N application effect on soil residual nitrogen in 2012 is similar to that in 2011. The accumulation of inorganic nitrogen in the 0-100 cm soil layer is decreased, negative to the N application rate when it is less than 225 kg/ha. The accumulation amounts of inorganic nitrogen under N application rates of 0 and 225 kg/ha treatments are 165%and 170%, respectively, in 2011 and less in 2012, while the soil nitrogen accumlate significantly when N application rate is higher than 300 kg/ha. The accumulation amounts of inorganic nitrogen under N application rates of 375 , 450 , and 600 kg/ha treatments in 2011 are about 17%, 388%, and 170% higher than those in 2012. The regression equations of nitrogen accumulation with the N application rates are y2011 =0. 0001x2 +0. 1013x-22. 537(R2 = 0. 9288), and y2012 = 0. 0003x2 + 0. 1417x - 52. 78(R2 = 0. 9583), respectively. Both the loss of nitrogen and surplus are significantly increased with the increase of the N application rate. The accumulation amounts of inorganic nitrogen are balanced under the N application rates of 187 kg/ha in 2011 and of 245 kg/ha in 2012 . The correlations between the yields of maize and the N application rate are parabolic or linear plus platform growth. There are no significant differences among the yield changes and the highest yields when the N application rate is higher than 300 kg/ha. The yield of maize is significantly lower than the highest yield when the net soil inorganic nitrogen accumulation equals zero can be expressed by. The nitrogen use efficiency is significantly reduced by an exponential relationship with the N application rate. There is an intersection point between the yield and the nitrogen use efficiency appeares at the N rate of 270 kg/ha, and that between residues of inorganic nitrogen and nitrogen utilization at the application rate of 340 kg/ha . [Conclusions]It is an optimized method that using the production effect, environment effect and fertilizer effect to determine the nitrogen input threshold, and the reasonable nitrogen application rate can increase the yield of maize, reduce the risk of nitrogen non-point source pollution and improve the nitrogen use efficiency. Therefore, using three curves method, the N application rate of 270-340 kg/ha is the optimum nitrogen input threshold in maintaining maize high production.
