【作者】 Sikander Khan Tanveer；

【导师】 廖允成；

【作者基本信息】 西北农林科技大学 ， 作物栽培学与耕作学， 2013， 博士

【摘要】 在旱作生态系统中，温室气体尤其是二氧化碳和氧化亚氮排放浓度的增加显著影响生态环境。这些气体浓度的增加不但有损健康的环境，同时损害了整个生产系统的可持续性。本研究设计了一个2年试验，旨在探讨不同耕作方法（深松耕，免耕，旋耕和翻耕）、覆盖水平（M0：无玉米秸秆覆盖，M1：有玉米秸秆覆盖）和氮肥水平（0，80，160，240和320公斤/公顷）对黄土高原旱作农区温室气体（CO₂和N₂O）排放和小麦作物生产力的影响。本试验为三因素裂区试验设计，以耕作方式为主区、覆盖为裂区、N素水平为再裂区。CO₂排放量使用便携式GXH-3010E1气体分析仪测定，在2年试验中每周测定一次，而N₂O排放仅在2011-12年对旋耕处理进行测定。同时测定SOC，土壤全氮，土壤酶，土壤pH值，土壤湿度，土壤温度等土壤理化特性，作物生长，作物光合，以及气温度，相对湿度和风速等不同的环境因素，杂草虫害，肥料利用效率和经小麦产量及经济效益也进行了记录。旋耕措施下CO₂排放量最高，与此相反，免耕措施下CO₂排放量最小。对于各氮肥水平，施氮量160公斤/公顷时的二氧化碳排放最低。2年试验中，2010-11年二氧化碳排放量高于2011-12。在2010-11年种植期间，作物秸秆覆盖显著增加了CO₂的排放量，然而在2011-12种植期间，在两种覆盖条件下，排放量相同。在耕作后，二氧化碳排放量迅速上升。降雨、空气温度等环境因素，土壤温度，土壤水分，SOC，C/N比，土壤土壤脲酶和土壤蔗糖酶均显著影响二氧化碳排放量。连续使用氮肥增加了N₂O向大气排放。2011-12年，旋耕法N₂O排放被记录。使用作物秸秆覆盖和未使用作物秸秆覆盖两个不同覆盖水平被使用。五种不同氮肥水平包括N0（0，公斤/公顷），N1（80公斤/公顷），N2（160公斤/公顷），N3（240公斤/公顷）和N4（320公斤N/公顷）被使用。最大的N₂O排放量出现在小麦种植的前三个星期。除N3（240公斤N/公顷）之外，其他氮肥处理条件下作物秸秆覆盖处理降低了N₂O的排放量。在整个生育期，最小的N₂O排放出现在N1（8O公斤/公顷）水平。除N3（240公斤/公顷），其它氮肥水平情况下应用作物秸秆覆盖增加了粮食产量。所以，可以得出结论，适当的氮肥水平结合作物秸秆覆盖对环境和经济效益有益。在孕穗期，抽穗期，籽粒形成期，作物成熟期等不同的作物生长阶段记录光合作用的数据。免耕处理表现出最大光合作用，其次为深松耕，同时旋耕和翻耕作情况下表现出最低光合作用。在作物生长的后期，秸秆覆盖提高了光合作用。同样，与N0相比，氮肥水平提高增加了光合作用，但当光合作用增加到一定限度后，氮肥施用对光合作用的提升效果并不显著。结果表明，保护性耕作、覆盖和应用适当的氮肥可以提高光合作用，这可以帮助在雨养生态条件下获得更多的粮食产量。降雨时间和降雨量显著影响粮食产量和水分利用效率，但整体而言，籽粒、整株以及降雨的最大水分利用效率分别为26.2公斤/公顷，和降雨的51.5千克/公顷和40.3公斤/公顷，均出现在免耕处理，其次为深松耕处理。秸秆覆盖水分利用效率与未覆盖处理相等。虽然两年度间降水利用效率在不同的氮肥水平间表现不同，但两年的平均值表明80公斤N/公顷的施氮量处理的水分利用效率最高。数据表明，免耕技术是获得最大水分利用效率的适宜耕作方法。使用不同的耕作方法和玉米秸秆覆盖技术提高了土壤中有机碳的含量，尤其是在0-10厘米土壤深度的有机碳含量。这有助于减少二氧化碳的排放。不同年间降雨时间和雨量的不同，导致谷物的产量显著变化。产量的不同也源于不同的生产管理方法，比如使用不同的耕作方法以及施用不同的氮肥，这些因素都显著地影响小麦产量。由于降雨含量不同，2010-2011年最大产量为免耕处理的6.58吨/公顷以及80公斤/公顷氮肥水平的6.72吨/公顷。2011-2012年采用同样的耕作方法，而最高产量出现在320公斤/公顷氮肥水平下，为7.46吨/公顷。根据两年的平均水平，与其他耕作方式或氮肥水平相比，免耕和80公斤N/公顷氮肥水平获得最大的粮食产量，即6.75吨/公顷和6.80吨/公顷。与未使用秸秆覆盖处理相比，使用秸秆覆盖于可减少高达40%的杂草侵扰。经济分析表明，适当免耕种植方法、使用秸秆覆盖和根据预计降雨最低限度地使用氮肥，不仅减少了温室气体的排放量，并且随着土壤环境的改善，减少了除草剂的使用。可见，在免耕，作物秸秆覆盖的基础上根据预计降雨量使用最少量的氮肥是既经济又环保的栽培耕作措施。更多还原

【Abstract】 Escalating concentrations of different Greenhouse gases particularly the emissions ofCO2and N₂O are very hazardous for the environment. Rising concentrations of these gasesare not only detrimental for the healthy environment but are also injurious for thesustainability of whole production system. A2year study was designed to assess the effects ofdifferent tillage methods （Chisel plough tillage, Zero-tillage, Rotary tillage and Mouldboardplough tillage）, two mulch levels （M0i.e. No corn residue mulch and M1i.e. Corn residuemulch） and5N fertilizer levels （0,80,160,240and320kg N ha-1） on the emissions ofGreenhouse gases （CO2and N₂O） and wheat crop productivity under the rainfed ecology ofLoess Plateau China. Factorial experiment with three replications, having strip, split-splitarrangement, with tillage methods in the main plots, mulch levels in the sub-plots and N-fertilizer levels in the sub-sub plots was used for this study. CO2emissions data was recordedevery week by using the portable GXH-3010E1gas analyzer during the both years of study,while N₂O data was recorded from the Rotary tillage during wheat crop growing season2011-12. Data was also recorded regarding different soil properties like SOC, total soil Nitrogen,Soil enzymes, soil pH, soil moistures, soil temperatures, crop growth, crop photosynthesis,different environmental factors like air temperatures, relative humidity and wind speed etc.Data was also recorded regarding weeds infestations, fertilizer use efficiencies and economicsof production of wheat crop by using the different management practices.Maximum emissions of CO2were recorded in case of Rotary tillage planting method, ascompared to the minimum emissions of CO2recorded in case of Zero tillage planting method.In case of N fertilizer levels minimum emissions were CO2were recorded in case of160kg Nha-1, N fertilizer level. In case of different planting year’s maximum emissions of CO2wererecorded during the cropping year2010-11as compared to the year2011-12. During the cropping year2010-11, applications of corn residue mulch significantly increased theemissions of CO2as compared with the non residue mulched treatments, while during thecropping year,2011-12equal emissions were recorded in case of both kinds of mulchtreatments. Higher emissions of CO2were recorded immediately after the tillage operations.Different environmental factors i.e. rains, air temperatures, soil temperatures, soil moisturesand some soil characteristics like SOC, C/N ratio and soil enzymes like soil Urease and soilInvertase had significant effects on the emissions of CO2.The continuous use of N fertilizers for crops production is consistently increasing theemissions of N₂O in the atmosphere. One year （2011-12）, N₂O emission data was recordedfrom the Rotary tillage planting method. Two different mulch levels were applied includingapplication of no corn residue mulch and as well as application of corn residue mulch. Fivedifferent N fertilizer levels were used including, N0（0, kg N/ha）, N1（80kg N/ha）, N2（160kgN/ha）, N3（240kg N/ha） and N4（320kg N/ha）. Maximum emissions of N₂O were recordedduring the first three weeks of planting of wheat crop. Except in case of N3,（240kg N/ha） N,fertilizer level, applications of corn residue mulch reduced the emissions of N₂O in case of allthe other N fertilizer levels. On cumulative basis, minimum emission of N₂O was recorded incase of N1（8o kg N/ha）, N fertilizer level. Except in case of N3（240kg N/ha）, applications ofcorn residue mulch increased the grain yields in all the other N fertilizer treatments. So it canbe concluded that the application of crop residue mulch along with appropriate N fertilizerlevel has many environmental and economical benefits.Photosynthesis data was recorded on the different crop growth stages i.e. booting stage,50%heading stage, grain formation stage and near to crop maturity stage. Maximumphotosynthesis was recorded in case of Zero tillage planting method, followed by Chiselplough tillage method, while minimum photosynthesis was recorded in case of Rotary tillageand Mouldboard plough tillage method. Application of mulch improved the photosynthesisprocesses as compared to the non residue mulched treatments especially at the later cropgrowth stages. Similarly, as compared with the N0, N fertilizer level, application of higherlevels of N fertilizer, enhanced the photosynthesis up to a certain limit but further increase inthe rate of N fertilizer could not improve this processes. The results show that conservationtillage, use of mulches and application of appropriate N fertilizer can improve thephotosynthesis processes, which can be helpful in getting the better grain yields from the rainfed ecologiesRainfall timings and concentrations significantly affected the grain yields and water useefficiencies but on overall basis maximum water use efficiencies i.e.26.2kg/ha mm-1,51.5kg/ha and40.3kg/ha mm-1for grains, biomass and rainfall were recorded in case of Zero tillage planting method, followed by Chisel plough tillage. Equal water use efficiencies wererecorded in case of corn residue mulched or non mulched treatments. Although both yearsthere were variations in the water use efficiencies by using the different N fertilizers levels buton two years average basis application of80kg N/ha gave the maximum water useefficiencies. Data shows that the adaptation of Zero tillage technology is the most suitabletillage method to get the maximum water use efficiencies.Use of different tillage methods and application of corn residue mulch increased theSoil organic carbon （SOC） contents of the soil especially in the0-10cm soil depth, whichhelped in the reductions of the emissions of CO2. Variations in the rainfall timings andquantities resulted in the significant variations of grains yields during the different croppingyears. Variations in the grain yields due to the different management practices like use ofdifferent tillage methods and application of different N fertilizer levels significantly affectedthe wheat crop grain yields. Due to variations in rainfalls, during the cropping year,2010-11,maximum grain yields i.e.6.58t/ha and6.72t/ha were recorded in case of Zero tillageplanting method and similarly in case of80kg N/ha, N fertilizer level, while during thecropping year2011-12equal grain yields were recorded in case of all tillage methods,however maximum grain yield （7.46t/ha） was recorded in case of320kg N/ha, N fertilizerlevel. On two years average basis, maximum grain yields i.e.6.75t/ha and6.80t/ha wererecorded in case of Zero tillage planting method and similarly in case of80kg N/ha, Nfertilizer level as compared with the other tillage methods or N fertilizer levels. Use of cornresidue mulch reduced the weeds infestation up to40%as compared with the non residuemulched treatments. Economic analysis shows that the adaptation of Zero tillage plantingmethod and minimum use of N fertilizer according to the projected rainfalls, along with theapplication of corn residue mulch not only reduces the emissions of Greenhouse gases, butalong with improving the soil health, also reduces the use of herbicides.It can be concluded that the adaptation of Zero tillage, use of corn residues as a mulchand the application of minimum N fertilizers according to the projected rainfall are botheconomic and environmental friendly.更多还原