發(fā)布時間：2018-04-28 13:23

  本文選題：溫室氣體 + 玉米-小麥輪作��； 參考：《中國農(nóng)業(yè)大學(xué)》2016年博士論文

【摘要】：針對不同輪作系統(tǒng)中氮肥過量及不合理施用和未來水資源緊缺將會成為四川盆地農(nóng)業(yè)可持續(xù)發(fā)展的限制因子,從2012年起本人在重慶市江津區(qū)進行單季稻轉(zhuǎn)換為不同輪作系統(tǒng)的田間試驗,動態(tài)監(jiān)測土壤N_2O、CH_4和生態(tài)系統(tǒng)CO2排放通量及農(nóng)業(yè)生產(chǎn)投入帶來的當量CO2排放,采用基于土壤的方法計算農(nóng)田凈溫室效應(yīng)(net Global Warming Potential,簡稱net GWP)。探討不同輪作體系下N_2O、CH_4的排放規(guī)律及凈溫室效應(yīng),分析影響溫室氣體排放和凈溫室效應(yīng)的主控因子,提出針對性減排措施,為該地區(qū)農(nóng)業(yè)的可持續(xù)發(fā)展提供理論指導(dǎo)。試驗設(shè)早旱輪作(玉米-小麥,MW)、水旱輪作(水稻-小麥,RW)、水稻-冬水休閑(水稻-休閑,RF)三種輪作體系為主處理,每種輪作體系設(shè)不施氮對照(N0：不施用氮肥)、優(yōu)化施氮(Nopt:小麥季96 kg N h-1,玉米季或水稻季150 kg N ha1).傳統(tǒng)施氮(Ncon:小麥季180 kg N ha-1,玉米季或水稻季225kgN ha-1)3個副處理。溫室氣體采用靜態(tài)箱-氣相色譜法進行田間原位測量,每周1-3次,共2周年。得到以下主要結(jié)果：(1)氮肥施用是農(nóng)田土壤N_2O排放的重要來源,主要是通過增加土壤無機氮含量而促進N_2O排放,降雨強度是玉米季土壤N_2O排放年際變化的主要原因。不同輪作體系比較,N_2O排放以MW RW RF;不同施氮水平比較,N_2O排放以NconNoptN0。小麥季、玉米季、水稻季Ncon和Nopt處理的N_2O平均排放因子分別為0.68～0.82%、3.16%、0.35～0.36%以及0.48～0.73%、2.23%、0.21～0.22%。這些結(jié)果表明,傳統(tǒng)處理較優(yōu)化處理有較高的N2O排放風險；稻麥輪作改為玉麥輪作,增加N2O排放,而將稻麥輪作改為水稻-冬水田輪作,則減少N_2O排放。(2)農(nóng)田CH_4排放以RF系統(tǒng)最高,RW次之,MW最低。由于施肥,灌溉和降雨的影響,小麥季、玉米季、水稻季土壤5cm的溫度僅能解釋6%、13%、14%的CH_4排放,同時稻季水層深度可解釋19%的CH_4排放。2013年度(第一年)單季稻改旱作,MW玉米季有明顯甲烷排放,2014年度(第二年)則未出現(xiàn)；RW系統(tǒng)兩年甲烷排放量無顯著差異；單季稻改為冬水田后,甲烷排放在第二年明顯增加。MW、RW、RF三輪作系統(tǒng)的兩年平均值均表現(xiàn)出甲烷的凈排放,并以水稻或玉米季為主。大量施氮后,抑制RW和MW系統(tǒng)甲烷排放,對RF系統(tǒng)無影響。MW、RW、RF體系第一年的甲烷排放量分別為13.5、26.7和89.8kg CH_4-C ha-1,第二年為第一年相應(yīng)體系的6.2%、85.1%和263.1%。在NO處理中,MW、RW、RF系統(tǒng)兩年平均的CH_4排放量分別為9.1、28.2、156.6 kg CH_4-Cha-1, Nopt處理分別為相應(yīng)對照處理的91.3%、107.9%、108.9%,Ncon處理分別為相應(yīng)對照處理的46.1%、54.5%、103.5%。(3)農(nóng)田生態(tài)系統(tǒng)呼吸存在明顯的年際變異,生態(tài)系統(tǒng)呼吸以2013年度2014年度；不同輪作體系比較,MW系統(tǒng)的農(nóng)田生態(tài)系統(tǒng)呼吸通量最高,RW系統(tǒng)次之,RF系統(tǒng)最低；隨著施肥量的增加,農(nóng)田生態(tài)系統(tǒng)呼吸明顯增加。農(nóng)田生態(tài)系統(tǒng)呼吸排放變化受溫度控制。小麥季CO2排放與箱內(nèi)溫度有較好的相關(guān)性,玉米季和水稻季CO2排放與5 cm土溫有較好的相關(guān)性,分別能夠解釋38.3%、28.6%、48.9%的生態(tài)系統(tǒng)呼吸。小麥季、玉米季CO2呼吸與WFPS有明顯的負相關(guān),但僅能解釋9.3%、8.5%的生態(tài)系統(tǒng)呼吸。(4)N_2O和CH_4產(chǎn)生的GWP和GHGI (Greenhouse Gas Intensity,指單位產(chǎn)量的溫室氣體排放強度)中,RW系統(tǒng)均為最低,RF系統(tǒng)均為最高；施肥處理的N_2O貢獻了MW系統(tǒng)GWP的90%,RW系統(tǒng)GWP中不低于40%,RF系統(tǒng)GWP中不足8%。MW和RW的凈溫室效應(yīng)中,除了監(jiān)測到的溫室氣體產(chǎn)生的當量CO2排放,由于生產(chǎn)效率較低,肥料投入也是很重要的一面；RW稻田灌溉是干旱年份溫室效應(yīng)的主要貢獻者,而RF系統(tǒng)中,最主要的貢獻是CH_4排放。從單季稻轉(zhuǎn)變?yōu)樗�旱輪作、旱旱輪作和冬水田之�?土壤有機碳發(fā)生了明顯的變化,旱旱輪作土壤有機碳表現(xiàn)為排放,冬水田土壤有機碳表現(xiàn)為明顯的碳固定,水旱輪作表現(xiàn)為弱的碳固定。旱旱輪作的net GWP和net GHGI均最高,而冬水田的均最低。
[Abstract]:Excessive nitrogen fertilizer and unreasonable application in different rotation systems and the shortage of future water resources will be the limiting factors for the sustainable development of agriculture in Sichuan basin. From 2012, the field experiment of single season rice conversion to different rotation systems in Jiangjin area of Chongqing city was carried out to dynamically monitor soil N_2O, CH_4 and CO2 emission fluxes in the ecosystem. And the equivalent CO2 emissions from agricultural production input, the net greenhouse effect of farmland (net Global Warming Potential, referred to as net GWP) was calculated based on the soil method. The emission laws of N_2O and CH_4 under different rotation systems and the net greenhouse effect were discussed, and the main controlling factors affecting the emission of greenhouse gas and the net greenhouse effect were analyzed, and the targeted reduction was proposed. In order to provide theoretical guidance for the sustainable development of agriculture in this area, the experiment set up three kinds of rotation systems, namely, early drought rotation (maize wheat, MW), water and drought rotation (rice wheat, RW), rice winter water leisure (rice leisure, RF), each rotation system without nitrogen control (N0: no nitrogen application) and optimized nitrogen application (Nopt: wheat season 96 kg N H -1, maize season or rice season 150 kg N HA1). Traditional nitrogen application (Ncon: wheat season 180 kg N HA-1, corn season or rice season 225kgN HA-1) 3 side treatments. Greenhouse gases were measured in situ using static box gas chromatography, 1-3 times a week, a total of 2nd anniversary. (1) application of nitrogen fertilizer is an important part of the field soil N_2O emission. The source, mainly by increasing the content of soil inorganic nitrogen to promote N_2O emission, the rainfall intensity is the main reason for the interannual variation of soil N_2O emission in the maize season. The N_2O emission is MW RW RF compared with the different rotation system, and the N_2O emission is based on the NconNoptN0. wheat season, the jade rice season, the Ncon and Nopt treatment of the rice season. The results were 0.68 to 0.82%, 3.16%, 0.35 to 0.36%, 0.48 to 0.73%, 2.23%, and 0.21 to 0.22%., the results showed that the traditional treatment had higher N2O emission risk than the rice wheat rotation, and the N2O emission was increased, and the rice wheat rotation was changed to rice winter water Da Waku, and the N_2O emission was reduced. (2) CH_4 emission from farmland was RF system Due to the effects of fertilization, irrigation and rainfall, the temperature of soil 5cm in wheat season, corn season, and rice season can only explain 6%, 13%, 14% CH_4 emissions due to fertilization, irrigation and rainfall. At the same time, the depth of the rice season water layer can be explained by 19% CH_4 emissions in.2013 year (first year) to dry rice, the MW corn season has obvious methane emission, 2014 (second years) is not in the 2014 year. There was no significant difference in methane emission in RW system for two years. After the single season rice was changed to winter water, the methane emission was obviously increased by.MW in second years. The average annual value of the RW and RF three wheel system showed the net methane emission and was dominated by rice or corn season. After a large amount of nitrogen application, the methane emission of RW and MW systems was suppressed, and.MW and RW were not affected to the RF system. The emission of methane in the first year of RF system is 13.5,26.7 and 89.8kg CH_4-C HA-1 respectively. The second year is 6.2%, 85.1% and 263.1%. in the first year of the corresponding system. The average CH_4 emission of MW, RW and RF systems in the two years is 9.1,28.2156.6, respectively, and the treatment is 91.3%, 107.9%, 108.9%, respectively. The respiration of ecosystem respiration in 46.1%, 54.5%, 103.5%. (3) farmland ecosystem has obvious interannual variation. The respiration of the ecosystem is in 2013 year 2014. Compared with the different rotation system, the respiratory flux of the MW system is the highest, the RW system is the second, the RF system is the lowest; as the amount of fertilizer increases, the farmland ecosystem calls The respiration rate of the farmland ecosystem was controlled by temperature. The CO2 emission from the wheat season had a good correlation with the temperature in the box. The CO2 emission from the corn season and the rice season had a good correlation with the 5 cm soil temperature, which could explain the ecological respiration of 38.3%, 28.6%, 48.9% respectively. There was a significant negative phase between the wheat season and the maize season CO2 respiration and WFPS. But it can only explain 9.3%, 8.5% of the ecosystem respiration. (4) GWP and GHGI produced by N_2O and CH_4 (Greenhouse Gas Intensity, the greenhouse gas emission intensity of unit output), RW system is the lowest, RF system is the highest, and the N_2O of the fertilizer treatment has contributed 90% of MW system GWP, not less than 40%. In the net greenhouse effect of RW, in addition to the monitoring of the equivalent CO2 emissions produced by greenhouse gases, fertilizer input is also an important aspect of the low production efficiency; RW rice field irrigation is the main contributor to the greenhouse effect in the drought years, and the most important contribution of the RF system is the CH_4 emission. After the winter water field, the soil organic carbon changed obviously, the soil organic carbon in the dry and dry rotation soil was discharged, the soil organic carbon in the winter water field was marked carbon fixation, and the water and drought rotation showed weak carbon fixation. The net GWP and net GHGI of the drought and drought rotation were the highest, while the winter water fields were the lowest.

【學(xué)位授予單位】：中國農(nóng)業(yè)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：S181
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本文編號：1815449