晋南黄土旱塬小麦养分投入与化肥减施经济环境效应评价

Evaluation on Fertilizer Application and Its Economic-Environmental Benefits Associated with Fertilizer Reduction Potential for Dryland Wheat in Loess Plateau of Southern Shanxi Province

【目的】明确晋南黄土旱塬冬小麦养分投入现状,为当地旱作冬小麦稳产增产、减肥增效和控制农田面源污染提供理论依据。【方法】通过连续9年对黄土旱塬984个小麦种植户进行施肥调查,采用基于冬小麦产量确定的推荐施肥量,评价农户施肥,分析农户施肥的减肥潜力及其经济和环境效益。【结果】调研农户小麦籽粒平均产量3 711 kg·hm^(-2),其中属于低产(≤3 200 kg·hm^(-2))和中产(3 200-4 220 kg·hm^(-2))的农户比例分别占56.0%和18.1%。农户氮肥、磷肥和钾肥的平均用量分别为292.3 kg N·hm^(-2)、159.8 kg P_(2)O_(5)·hm^(-2)和92.0 kg K_(2)O·hm^(-2)。随着产量水平提高,施肥过量(即高投入+很高投入)的农户比例增加,其中氮肥、磷肥和钾肥施用过量的农户比例分别为68.7%、65.1%和57.9%。在各产量水平投入高和很高的农户减肥潜力较大,其中高投入的农户氮肥、磷肥和钾肥减施量为24.1 kg N·hm^(-2)、12.8 kg P_(2)O_(5)·hm^(-2)和6.2 kg K_(2)O·hm^(-2),减少比例依次为15.9%、16.7%和16.7%;很高投入的农户氮肥、磷肥和钾肥减施量为250.9 kg N·hm^(-2)、205.7 kg P_(2)O_(5)·hm^(-2)、124.6 kg K_(2)O·hm^(-2),减少比例依次为66.5%、76.7%和80.0%。进一步分析表明,高投入和很高投入的农户化肥减施后经济效益可增加251和3 425元/hm^(2),即分别增加4.0%和55.0%;高投入的农户氮肥、磷肥和钾肥的农学效率可分别提高18.8%、23.2%和22.1%,很高投入的可分别提高192.5%、321.3%和388.1%;高投入的农户氮肥、磷肥和钾肥的偏生产力可分别提高20.2%、23.7%和19.2%,很高投入的可分别提高210.4%、317.9%和388.1%。同时,合理降低高投入和很高投入的农户施氮量,N_(2)O排放可分别减少0.3和6.3 kg N_(2)O·hm^(-2),减少幅度为11.2%和72.5%;NH_3挥发分别减少14.1和90.7 kg NH_3 hm^(-2),减幅为20.8%和62.8%;NO_(3)^(-)-N淋洗减少3.1和231.1 kg NO_(3)^(-)-N·hm^(-2),减幅为4.9%和79.6%;整体上,总氮污染物(包括N_(2)O排放、NH_(3)挥发和NO_(3)^(-)-N淋洗)可分别减少17.4和328.1 kg·hm^(-2),减幅13.1%和74.0%,节约氮肥12.5和130.9 kg N·hm^(-2),减少氮肥投入65.0和683.3元/hm~2。【结论】通过基于产量的农户施肥评价、减肥潜力估测、化肥减施后的经济效益和氮化合污染物的减排效应分析,明确了高和很高投入的农户氮磷钾减施潜力分别为24.1-250.9 kg N·hm^(-2)、12.8-205.7 kg P_(2)O_(5)·hm^(-2)、6.2-124.6 kg K_(2)O·hm^(-2),且化肥减施后农户的经济收益提高251-3 425元/hm^(2),氮、磷、钾肥的农学效率分别提高18.8%-192.5%、23.2%-321.3%、22.1%-388.1%,同时,氮、磷、钾偏生产力提高20.2%-210.4%、23.7%-317.9%、19.2%-388.1%,还能减少包括N_(2)O排放、NH_(3)挥发、NO_(3)^(-)-N淋洗等总氮污染物的排放17.4-328.1 kg·hm^(-2)。该研究全面系统地揭示了当前旱作小麦生产中存在的资源环境问题、面临的挑战与机遇,为节本、增效的环境友好型施肥提供一定的理论依据。

【Objective】The aim of this study was to clarify situation of the farmers’nutrient application,so as to provide a theory base for the realization of stable and high yield,high nutrient use efficiency,and lower environmental pollution in dryland wheat production.【Method】A 9-yr survey of 984 farmers was carried out,and a yield based fertilizer recommendation method were used to analyze and evaluate their nutrient applications and the fertilizer reduction potential and economic-environmental benefits in Loess Plateau.【Result】The farmers’wheat yield was lower,with the average of 3711 kg·hm^(-2),and they were allocated into three groups as:low(≤3200 kg·hm^(-2))and moderate(3200-4220 kg·hm^(-2)),respectively,accounting for 56.0%and 18.1%of the total farmers.Farmers’nitrogen(N),phosphorus(P_(2)O_(5))and potassium(K_(2)O)application were very high,with the average of 292.3 kg N·hm^(-2),159.8 kg P_(2)O_(5)·hm^(-2)and 92.0 kg K_(2)O·hm^(-2).And the proportion of the high-application farmers were N 68.7%and P_(2)O_(5)65.1%and K_(2)O 57.9%,respectively,which was large in low-yield level.Generally,these high-application farmers were recommended to reduce 24.1 kg N·hm^(-2),12.8 kg P_(2)O_(5)·hm^(-2),and 6.2 kg K_(2)O·hm^(-2),and the reduction range was N 15.9%,P 16.7%and K 16.7%,respectively,but these very high-application farmers were recommended to reduce 250.9 kg N·hm^(-2),205.7 kg P_(2)O_(5)·hm^(-2),and 124.6 kg K_(2)O·hm^(-2),and the reduction range was 66.5%,76.7%,and 80.0%,respectively.Then,their economic effects increased by 251 yuan/hm2 and 3425 yuan/hm2,4.0%and 55.0%,NPK agronomic efficiency increased by N 18.8%,P 23.2%,and K 22.1%for the high farmers,and N 192.5%,P 321.3%,and K 388.1%for the very high farmers.NPK partial productivity increased by N 20.2%,P 23.7%,and K 19.2%,and N 210.4%,P 317.9%,K 388.1%,respectively.According to the estimation,the environmental impact of reducing nitrogen application was that emission of the N-pollutant reduced,such as N2O emission decreased by 0.3 kg N2O·hm^(-2)and 6.3 kg N2O·hm^(-2),11.2%and 72.5%,NH3 volatilization decreased by 14.1 kg NH3·hm^(-2)and 90.7 kg NH3·hm^(-2),20.8%and 62.8%,and NO3 leaching decreased by 3.1 kg NO3·hm^(-2)and 231.1 kg NO3·hm^(-2),4.9%and 79.6%,respectively.Total nitrogen pollutants(including N2O emission,NH3 volatilization and NO3 leaching)reduced 17.4 kg·hm^(-2)and 328.1 kg·hm^(-2),with 13.1%and 74.0%,respectively.In total,12.5 kg N·hm^(-2)and 130.9 kg N·hm^(-2)with 65.0 yuan/hm2 and 683.3 yuan/hm2 were saved,respectively.【Conclusion】In this paper,based on the wheat yield,the farmer’s fertilization was evaluated,and the potential of reducing excessive fertilization was estimated,and the economic benefits and the effect of the reducing nitrogen-pollutants emission were analyzed through reducing fertilizer application.It was known that the farmers with high and very-high fertilizer application not only had different potential for reducing fertilizer application,such as 24.1-250.9 kg N·hm^(-2),12.8-205.7 kg P_(2)O_(5)·hm^(-2),6.2-124.6 kg K_(2)O·hm^(-2),but also farmers’economic benefits was improved by 251-3425 yuan/hm2,and fertilizer agronomic efficiency was improved by N 18.8%-192.5%,P 23.2%-321.3%,K 22.1%-388.1%,and partial productivity was improved by N 20.2%-210.4%,P 23.7%-317.9%,K 19.2%-388.1%,and the emission of total nitrogen pollutants(including N2O,NH3 and NO3)was reduced by 17.4-328.1 kg·hm^(-2).This study comprehensively and systematically revealed the resource and environmental problems,challenges and opportunities in the current dry wheat production,which provided a certain theoretical basis for an environment-friendly fertilization with saving cost and increasing efficiency.