發(fā)布時間：2018-06-07 00:39

  本文選題：填閑作物 + 紫云英�。� 參考：《華中農(nóng)業(yè)大學》2016年博士論文

【摘要】：氮素形態(tài)轉(zhuǎn)化與循環(huán)過程是元素生物地球化學過程中的重要一環(huán)。水稻(Oryza sativa L.)是我國主要種植的三大糧食作物之一。氮素是水稻等作物生長發(fā)育以及形成一定產(chǎn)量的首要限制性因素。自改革開放以來,我國長期不合理施用化肥尤其是氮肥,至上世紀90年代末,無論是氮肥施用總量還是施用強度均已位居世界前列,而有機物料投入用量則驟然下降。隨著時間的推移,由于長期過量且不合理施用氮肥,不僅其當季利用率比較低,大量硝態(tài)氮累積于土壤中而產(chǎn)生下滲淋溶損失、NH3揮發(fā)和硝化反硝化脫氮(NOx)等途徑損失進入土壤、水體和大氣等環(huán)境中而引發(fā)一系列環(huán)境問題,而且氮肥的增產(chǎn)效益逐年下降。種植和利用冬季填閑作物是我國傳統(tǒng)農(nóng)業(yè)的精華和重要組成部分,其鮮草還田經(jīng)土壤微生物腐解釋放出來的氮素同樣可被水稻作物吸收利用,還可能影響了土壤氮庫中各形態(tài)氮素分布、轉(zhuǎn)化及其歸趨等一系列生物地球化學過程,從而影響氮素生物有效性以及稻田生產(chǎn)力的可持續(xù)性。以往關(guān)于填閑作物的多研究集中于旱地土壤或者更關(guān)注于其在培肥改土、供應下茬作物養(yǎng)分等方面的作用,而關(guān)于填閑作物對淹水稻田系統(tǒng)土壤供氮能力和水稻生產(chǎn)力持續(xù)變化以及氮素形態(tài)轉(zhuǎn)化的作用等方面的機制尚不清楚。因此,本文擬采用紫云英(Astragalus sinicus L.)為模式填閑作物,通過大田長期定位試驗、室內(nèi)盆栽和15N示蹤(交叉標記)微區(qū)試驗相結(jié)合的方法,探討填閑作物對氮素形態(tài)轉(zhuǎn)化、硝化反硝化等過程以及稻田供氮能力及其生產(chǎn)力持續(xù)演化過程的影響機理,研究結(jié)果將對外源物質(zhì)投入相對較少的南方水稻種植體系中合理利用填閑作物,提高稻田土壤中氮素貯藏和循環(huán)能力和利用率,減少稻田氮素損失及其環(huán)境風險,維持稻田系統(tǒng)生產(chǎn)力與可持續(xù)性具有十分重要的意義。主要結(jié)論如下:1.采用室內(nèi)土壤盆栽試驗研究了尿素配施紫云英對單季稻田系統(tǒng)氮素氣態(tài)損失的影響。結(jié)果表明,單季稻田氮素的NH3揮發(fā)損失率超過20%,而N2O損失率則小于1%。與尿素單施相比,尿素配施紫云英顯著降低表面水中銨態(tài)氮含量和分蘗期土壤中羥胺還原酶活性以及各生育期土壤中硝化反硝化細菌數(shù)量與硝酸和亞硝酸還原酶活性,從而分別顯著降低單季稻田NH3揮發(fā)量和N2O排放量14.6%和45.2%,進而分別降低N2O的增溫潛勢和溫室氣體強度45.2%和46.8%。2.與尿素單施相比,尿素配施紫云英顯著增加水稻各生育期土壤中固定態(tài)銨、土壤微生物量碳與氮含量以及銨態(tài)氮和非酸解氮(NAHN)含量,卻降低硝態(tài)氮含量;增加氨基酸態(tài)氮(AAN)、氨基糖態(tài)氮(ASN)和酸解氨態(tài)氮(AHAN)含量,而降低酸解未知態(tài)氮(AHUN)含量,從而分別增加無機氮、酸解氮(AHN)和總氮含量5.13%-24.2%、3.44%-8.36%和9.17%-10.9%,新增加的AHN中以AAN和AHAN為主。3.與尿素單施相比,尿素配施紫云英分別顯著增加土壤中細菌、放線菌、真菌、固氮菌數(shù)量和脲酶、蛋白酶、蔗糖酶活性14.5%-36.6%和15.3%-31.1%,但分別顯著降低土壤中氨氧化細菌(AOB)數(shù)量和氨氧化古菌基因(AOA amo A)豐度24.6%和66.4%;顯著降低15NU對分蘗期土壤中ASN、AHUN、AHAN和NAHN及其對成熟期土壤中AAN和ASN的貢獻率,卻顯著增加其對成熟期土壤中AHUN、NAHN和固定態(tài)銨的貢獻率。通徑分析結(jié)果則表明,AHAN是土壤中15NU的暫時累積庫,而NAHN則是穩(wěn)定的儲存庫。4.與尿素單施相比,尿素配施紫云英促進水稻各生育期對15NU的吸收累積及其在實籽粒中的分配量,降低其對土壤氮(SoilN)的吸收累積以及15NU在秕谷中的分配量,從而顯著提高15NU利用率46.1%-83.0%,降低水稻對土壤氮素的依存率14.0%,改善產(chǎn)量各構(gòu)成要素(每穗實粒數(shù)、結(jié)實率和千粒重),從而增加籽粒產(chǎn)量3.02%。5.水稻收獲后,種植填閑作物紫云英分別顯著增加盛花期土壤總氮、固定態(tài)銨、土壤微生物量氮和銨態(tài)氮含量,降低硝態(tài)氮含量;增加盛花期土壤中AAN、ASN和AHAN含量,降低AHUN含量,最終分別平均增加酸解氮和非酸解氮含量13.0%和15.9%,另外,種植填閑作物紫云英還顯著增加殘留15NU對盛花期土壤中銨態(tài)氮、AAN、ASN和AHAN的貢獻率6.31%-22.3%,而分別降低其對土壤總氮、硝態(tài)氮、固定態(tài)銨和AHUN、AHN、NAHN的貢獻率8.28%-85.7%和6.37%-33.2%。6.在大田條件下,研究了紫云英和尿素不同配比(紫云英氮分別替代20%-80%尿素氮)對雙季稻田系統(tǒng)土壤供氮能力及其生產(chǎn)力可持續(xù)演變過程的影響。結(jié)果表明,不施肥或者尿素單施均不利于稻田系統(tǒng)生產(chǎn)力的可持續(xù)性發(fā)展。N80M20或N60M40處理條件下,耕層土壤有機質(zhì)和總氮含量以及早稻、晚稻籽粒和秸稈及其周年產(chǎn)量均隨時間的推移呈增加趨勢,而N100、N40M60或N20M80處理早稻、晚稻籽粒和秸稈及其周年產(chǎn)量變化趨勢則相反。與N100相比,N80M20或N60M40處理顯著提高耕層土壤有機質(zhì)、總氮、銨態(tài)氮含量和無機氮總量,促進水稻地上部對氮素的吸收累積,提高水稻籽粒和秸稈周年產(chǎn)量及其可持續(xù)指數(shù)以及氮素農(nóng)學利用率和偏生產(chǎn)力,而N40M60或N20M80處理則均表現(xiàn)為顯著降低趨勢。另外,紫云英替代尿素均顯著降低耕層土壤硝態(tài)氮含量。
[Abstract]:Nitrogen form transformation and circulation process is an important part of the elemental biogeochemical process. Rice (Oryza sativa L.) is one of the three major grain crops planted in China. Nitrogen is the primary limiting factor for the growth and development of rice and other crops. Since the reform and opening up, China has been using fertilizer for a long time. In particular, nitrogen fertilizer, at the end of the 90s of the last century, both the total amount of nitrogen fertilizer application and the application intensity have been in the forefront of the world, while the amount of organic materials dropped suddenly. With the passage of time, due to the long and unreasonable application of nitrogen fertilizer, not only the utilization ratio of the nitrogen fertilizer is lower, but a large amount of nitrate nitrogen is accumulated in the soil. Loss of leach, NH3 volatilization and nitrification denitrification and denitrification (NOx) are lost into the soil, water and atmosphere, which cause a series of environmental problems, and the benefits of nitrogen fertilizer increase year by year. Planting and utilization of winter leisure crops is the essence and important part of traditional agriculture in China, and its fresh grass is returned to soil by soil microorganism. The nitrogen released by decomposition can also be absorbed and utilized by rice crops, and it may also affect the distribution of nitrogen in the soil nitrogen pool, transformation and its return to a series of biogeochemical processes, thus affecting the bioavailability of nitrogen and the sustainability of the productivity of rice fields. Soil may be more concerned with the role of soil nutrient in the soil and the supply of crop nutrients, while the mechanism for soil nitrogen supply capacity and the continuous change of rice productivity and the role of nitrogen morphologic transformation in the flooded rice field system are not clear. Therefore, this paper is to use Astragalus sinicus L. as a model. In this paper, the mechanism of nitrogen morphologic transformation, nitrification and denitrification, nitrogen supply capacity and the continuous evolution of productivity in paddy fields were discussed by long-term location test in field and combined with 15N tracer microarea test. The results of the research will be relative to foreign substances. It is of great significance to improve nitrogen storage and recycling capacity and utilization in paddy soil, reduce nitrogen loss and environmental risk in paddy soil, reduce nitrogen loss and environmental risk in paddy soil, and maintain the productivity and sustainability of rice field system. The main conclusions are as follows: 1. a pot experiment in indoor soil was used to study urea. The results showed that the loss rate of NH3 volatilization of nitrogen in single season rice field was more than 20%, while the loss rate of N2O was less than that of 1%. compared with that of urea in single application. Urea was significantly reduced in the surface water and the activity of hydroxylamine reductase in the tillering stage and the soil of each growth period. The number of nitrification and denitrifying bacteria in the soil and the activity of nitric acid and nitrous reductase significantly decreased NH3 volatilization and N2O emissions by 14.6% and 45.2% in single cropping rice fields, respectively, and then decreased the temperature potential of N2O and the greenhouse gas intensity 45.2% and 46.8%.2., respectively, compared with the single application of urea. The medium fixed ammonium, soil microbial biomass carbon and nitrogen content, ammonium nitrogen and non acid nitrogen (NAHN) content decreased nitrate nitrogen content, increased amino acid nitrogen (AAN), amino sugar nitrogen (ASN) and acid ammonia nitrogen (AHAN) content, and decreased the content of unknown nitrogen (AHUN) in acid solution, thus increasing the content of inorganic nitrogen (AHN) and total nitrogen content 5.13%-2 respectively. 4.2%, 3.44%-8.36% and 9.17%-10.9%, compared with the single application of AAN and AHAN in the newly added AHN, the application of urea to the application of the urea with the urea and the application of the urea to the actinomycetes, fungi, nitrogen fixing bacteria and urease, protease, invertase activity 14.5%-36.6% and 15.3%-31.1% respectively, respectively, decreased the amount of ammonia oxidizing bacteria (AOB) in the soil, respectively. The abundance of AOA amo A was 24.6% and 66.4%, and the contribution rate of 15NU to ASN, AHUN, AHAN and NAHN and their contribution to AAN and ASN in the mature soil were significantly reduced, but the contribution rate to AHUN, NAHN and fixed ammonium in mature soil was significantly increased. In addition, NAHN is a stable storage.4.. Compared with single application of urea, urea is used to promote the absorption and accumulation of 15NU in each growth period of rice and its distribution in the real grain, the absorption and accumulation of nitrogen (SoilN) and the distribution of 15NU in the grain, thus significantly improving the 15NU utilization rate 46.1%-83.0% and reducing rice. The dependence rate of soil nitrogen was 14%, improving the yield components (the number of grain per panicle, seed setting rate and 1000 grain weight), thus increasing grain yield 3.02%.5. rice after the harvest, the planting and filling crops increased significantly the total soil nitrogen, fixed ammonium, soil microbiological nitrogen and ammonium nitrogen content, and decreased nitrate nitrogen content; The content of AAN, ASN and AHAN in the flowering soil decreased AHUN content, and the content of acid nitrogen and non acid nitrogen was increased by 13% and 15.9%, respectively. In addition, the contribution of residual 15NU to ammonium nitrogen, AAN, ASN and AHAN in the flowering soil was 6.31%-22.3%, and the total nitrogen, nitrate nitrogen and immobilization were reduced respectively. The contribution rate of ammonium and AHUN, AHN, NAHN was 8.28%-85.7% and 6.37%-33.2%.6. in field conditions, and the effects of different proportions of carbamide and urea on the capacity of soil nitrogen supply and the sustainable evolution of productivity in the system of double cropping rice field were studied. The results showed that no fertilization or single application of urea was not favorable. Under the condition of the sustainable development of rice field system productivity, the content of organic matter and total nitrogen in the soil and the yield of early rice, late rice grain and straw and their annual yield increased with time under.N80M20 or N60M40 treatment conditions, while N100, N40M60 or N20M80 treatment of early rice, late rice seed and straw and the trend of annual yield changes were the opposite. Compared with N100, N80M20 or N60M40 treatment significantly improved soil organic matter, total nitrogen, ammonium nitrogen and total inorganic nitrogen, promoted the accumulation of nitrogen in the upper part of rice, increased the annual yield and sustainability index of rice grain and straw, as well as nitrogen agronomy utilization and partial productivity, while N40M60 or N20M80 treatment showed significant difference. In addition, the substitution of Chinese milk vetch for urea significantly reduced nitrate nitrogen content in the topsoil.
【學位授予單位】：華中農(nóng)業(yè)大學
【學位級別】：博士
【學位授予年份】：2016
【分類號】：S158;S142.1
，

本文編號：1988876