節(jié)水灌溉稻田水氮遷移轉化機理及模擬
發(fā)布時間：2018-09-06 18:09
【摘要】：水稻是中國主要的糧食作物之一,稻田種植面積約占糧食作物種植總面積的28%,其產量約占糧食作物總產量的40%。稻作區(qū)水資源短缺已成為當地農業(yè)生產中的重要問題。與傳統(tǒng)淹灌稻田相比,干濕交替稻田面臨的水氮遷移轉化問題更為復雜,受土壤水分和溫度變化的影響更為嚴重。節(jié)水和省肥(氮肥)這兩個水稻生產中重要的目標在干濕交替稻田中可能互為一對矛盾體。如何讓干濕交替灌溉達到此兩目標最優(yōu),有賴于研究水氮在干濕交替水稻土壤中的遷移轉化機理,確定合理的精確灌溉制度和氮肥施用措施。本文以稻田田間土壤-水稻-大氣連續(xù)體系統(tǒng)為研究對象,采用野外田間水氮試驗觀測,室內土壤理化分析和田間一維水氮遷移轉化模擬等三種手段,研究了水氮在干濕交替條件下的遷移轉化規(guī)律,揭示了稻田水氮情勢隨灌溉和降水變化的內在機理,探求了干濕交替稻田節(jié)水、省肥和高產的水氮高效利用機制。本文主要研究內容和結論如下：(1)試驗監(jiān)測了干濕交替灌溉和長期淹灌稻田水滲漏和氮素滲漏量,比較研究了干濕交替灌溉的運用對水稻生長和作物產量的影響,以及干濕交替稻田與傳統(tǒng)淹灌稻田水氮入滲的區(qū)別與聯系。干濕交替節(jié)水灌溉在田間層面對產量沒有不利的影響。施氮能顯著增加糧食產量,但氮素生產率反而隨著施氮量增加而下降。干濕交替灌溉的成功實施減少了灌溉水的投入,一是由于減少入滲和滲漏損失。但是,由于在干燥階段形成的裂縫,干燥后再濕潤時期的優(yōu)先流造成大量的田間水滲漏流失。犁底層的土壤是防止?jié)B漏的關鍵,所以干燥時期的裂縫和收縮不應該延伸至犁底層。干濕交替灌溉田塊的地下水的毛細上升占水投入總量的26.1-27.4%。干濕交替灌溉在很大程度上減少了灌溉用水,二是由于其增加了地下水毛細上升。因此,在設計灌溉制度時應該考慮地下水毛細上升對節(jié)水灌溉的貢獻。水稻生長季節(jié)干濕交替灌溉田塊滲漏水硝態(tài)氮濃度比同時期長期淹灌田塊高64%,干濕交替灌溉田塊的硝態(tài)氮滲漏損失比長期淹灌田塊增加了29.4%。故干濕交替灌溉能誘導更高的氮素損失,增加稻田氮素滲漏的風險。干濕交替灌溉稻田和長期淹灌稻田中氮素的來源和去向均有很大不同。相較于長期淹灌,干濕交替灌溉加強了氮素轉化過程,包括硝化-反硝化,礦化和揮發(fā)作用等,從而增加了氮素的氣態(tài)排放和潛在的溫室氣體(N2O和NH4)排放。水稻可持續(xù)生產中干濕交替灌溉的成功實施需要充分考慮此負面效應。(2)針對室內外長期水氮試驗,構建土壤特征參數、田間水氮情勢和氣候微環(huán)境數據庫,利用其進行了HYDRUS-1D和系統(tǒng)動力學模型模擬研究。系統(tǒng)動力學模型能夠最大限度地簡化田間水氮平衡分析,HYDRUS-1D模型能很好地處理干濕交替灌溉稻田和長期淹灌稻田中動態(tài)變化的邊界條件。盡管HYDRUS-1D模型不能通過一階動力反應鏈完全描述所有氮素轉化過程,稻田各形態(tài)氮素濃度和平衡能夠通過集合一些相似的氮素轉化過程,利用HYDRUS-1D模型來分析和模擬。因為HYDRUS-1D模型能夠處理氮素轉化參數值對土壤含水量的變化,所以HYDRUS-1D模型能很好得被應用于比較干濕交替灌溉稻田和長期淹灌稻田中的水氮情勢,評價稻田中水氮平衡各要素,為稻田水氮管理提供決策依據。(3)試驗研究了南方水稻灌區(qū)塘堰系統(tǒng)水肥重復利用對區(qū)域節(jié)水和減少農業(yè)面源污染的作用。研究表明,在水稻生長季節(jié),灌溉塘堰可以有效地提高農業(yè)排水再利用和減少污染物排放。降水是決定塘堰回歸水再用率的決定性因素。充分利用塘堰的蓄水容積收集上游稻田回歸水和調控塘堰出流最大限度用于下游灌溉同樣可以提高塘堰回歸水利用率。塘堰水質監(jiān)測表明,灌溉塘堰去除農田排水中47.2%的總磷和60.8%的總氮,并對增加農業(yè)排水和灌區(qū)徑流的泥沙沉降,其懸浮物去除率平均達到68.4%。銨態(tài)氮是稻田回歸水中的主要氮素污染物,而顆粒態(tài)磷是回歸水中的主要磷素污染物。顆粒態(tài)磷占灌溉塘堰入流總磷的90%。較長的水力停留時間有利于提高總氮負荷去除率,而磷負荷去除率與水力停留時間關系不確定。因此,整合灌溉塘堰對回歸水和營養(yǎng)物的再利用,對減少農田氮和磷向區(qū)域外排放有重要意義,對稻田的生態(tài)環(huán)境改善具有積極意義。
[Abstract]:Rice is one of the main grain crops in China. The planting area of paddy field accounts for 28% of the total planting area and its yield accounts for 40% of the total grain yield. Water shortage in paddy field has become an important problem in local agricultural production. Water saving and fertilizer saving (nitrogen fertilizer) are two important objectives in rice production, which may be a pair of contradictions in alternate dry and wet paddy fields. In this paper, the soil-rice-atmosphere continuum system in paddy field was used as the research object to study the transfer and transformation of water and nitrogen under the condition of alternating wetting and drying by means of field water and nitrogen experimental observation, indoor soil physical and chemical analysis and field one-dimensional water and nitrogen transfer and transformation simulation. The main research contents and conclusions are as follows: (1) The water and nitrogen leakage and nitrogen leakage of paddy fields under alternate irrigation and long-term flooding irrigation were monitored and compared. The effect of alternate irrigation on rice growth and crop yield, and the difference and relationship between dry-wet alternate paddy field and traditional flooded paddy field were studied. Successful implementation of wet alternate irrigation reduces the input of irrigation water. First, it reduces the loss of infiltration and leakage. However, due to the cracks formed in the drying stage, preferential flow during the drying and wetting period results in a large amount of field water leakage and loss. The soil at the bottom of the plough is the key to prevent leakage, so the cracks and shrinkage during the drying period do not occur. The capillary rise of groundwater accounts for 26.1-27.4% of the total water input in dry-wet alternate irrigation fields. Dry-wet alternate irrigation greatly reduces irrigation water use and increases the capillary rise of groundwater. Therefore, the contribution of capillary rise of groundwater to water-saving irrigation should be considered in designing irrigation schemes. Nitrate nitrogen concentration in seepage water of paddy field under alternate dry-wet irrigation was 64% higher than that under long-term flooding irrigation during the growing season, and nitrate nitrogen loss in alternate dry-wet irrigation was 29.4% higher than that under long-term flooding irrigation. Compared with long-term flooding irrigation, dry-wet alternative irrigation enhances nitrogen transformation processes, including nitrification-denitrification, mineralization and volatilization, thus increasing nitrogen gaseous emissions and potential greenhouse gas emissions (N2O and NH4). Successful implementation of alternative irrigation requires full consideration of this negative effect. (2) For indoor and outdoor long-term water and nitrogen experiments, soil characteristic parameters, field water and nitrogen situation and climatic micro-environment database were constructed, and HYDRUS-1D and system dynamics model were used to simulate the field water and nitrogen balance. The HYDRUS-1D model can well deal with the boundary conditions of dynamic changes in paddy fields under alternate dry-wet irrigation and long-term flooding irrigation. Although the HYDRUS-1D model can not fully describe all nitrogen transformation processes through a first-order dynamic response chain, the concentration and balance of nitrogen forms in paddy fields can be combined by some similar nitrogen transformation processes, and the H-DRUS-1D model can be used to describe all nitrogen transformation processes in paddy fields. Because HYDRUS-1D model can deal with the change of soil water content caused by nitrogen transformation parameters, HYDRUS-1D model can be well applied to compare the water and nitrogen situation in paddy fields under dry-wet alternate irrigation and long-term flooding irrigation, to evaluate the water and nitrogen balance in paddy fields, and to provide a decision for paddy field water and nitrogen management. (3) The effect of water and fertilizer reuse on regional water saving and agricultural non-point source pollution reduction in the pond and weir system of southern rice irrigation area was studied experimentally. Fully utilizing the storage capacity of the pond weir to collect the returning water from the upstream paddy field and regulate the outflow of the pond weir for the downstream irrigation can also increase the utilization rate of the returning water from the pond weir. The average removal rate of suspended solids was 68.4%. Ammonium nitrogen was the main nitrogen pollutant in the returning water of paddy field, and particulate phosphorus was the main phosphorus pollutant in the returning water. Therefore, the reuse of returning water and nutrients by integrated irrigation ponds and weirs is of great significance to reduce nitrogen and phosphorus emission from farmland and to improve the ecological environment of paddy fields.
【學位授予單位】：武漢大學
【學位級別】：博士
【學位授予年份】：2016
【分類號】：S511
本文編號：2227124
[Abstract]:Rice is one of the main grain crops in China. The planting area of paddy field accounts for 28% of the total planting area and its yield accounts for 40% of the total grain yield. Water shortage in paddy field has become an important problem in local agricultural production. Water saving and fertilizer saving (nitrogen fertilizer) are two important objectives in rice production, which may be a pair of contradictions in alternate dry and wet paddy fields. In this paper, the soil-rice-atmosphere continuum system in paddy field was used as the research object to study the transfer and transformation of water and nitrogen under the condition of alternating wetting and drying by means of field water and nitrogen experimental observation, indoor soil physical and chemical analysis and field one-dimensional water and nitrogen transfer and transformation simulation. The main research contents and conclusions are as follows: (1) The water and nitrogen leakage and nitrogen leakage of paddy fields under alternate irrigation and long-term flooding irrigation were monitored and compared. The effect of alternate irrigation on rice growth and crop yield, and the difference and relationship between dry-wet alternate paddy field and traditional flooded paddy field were studied. Successful implementation of wet alternate irrigation reduces the input of irrigation water. First, it reduces the loss of infiltration and leakage. However, due to the cracks formed in the drying stage, preferential flow during the drying and wetting period results in a large amount of field water leakage and loss. The soil at the bottom of the plough is the key to prevent leakage, so the cracks and shrinkage during the drying period do not occur. The capillary rise of groundwater accounts for 26.1-27.4% of the total water input in dry-wet alternate irrigation fields. Dry-wet alternate irrigation greatly reduces irrigation water use and increases the capillary rise of groundwater. Therefore, the contribution of capillary rise of groundwater to water-saving irrigation should be considered in designing irrigation schemes. Nitrate nitrogen concentration in seepage water of paddy field under alternate dry-wet irrigation was 64% higher than that under long-term flooding irrigation during the growing season, and nitrate nitrogen loss in alternate dry-wet irrigation was 29.4% higher than that under long-term flooding irrigation. Compared with long-term flooding irrigation, dry-wet alternative irrigation enhances nitrogen transformation processes, including nitrification-denitrification, mineralization and volatilization, thus increasing nitrogen gaseous emissions and potential greenhouse gas emissions (N2O and NH4). Successful implementation of alternative irrigation requires full consideration of this negative effect. (2) For indoor and outdoor long-term water and nitrogen experiments, soil characteristic parameters, field water and nitrogen situation and climatic micro-environment database were constructed, and HYDRUS-1D and system dynamics model were used to simulate the field water and nitrogen balance. The HYDRUS-1D model can well deal with the boundary conditions of dynamic changes in paddy fields under alternate dry-wet irrigation and long-term flooding irrigation. Although the HYDRUS-1D model can not fully describe all nitrogen transformation processes through a first-order dynamic response chain, the concentration and balance of nitrogen forms in paddy fields can be combined by some similar nitrogen transformation processes, and the H-DRUS-1D model can be used to describe all nitrogen transformation processes in paddy fields. Because HYDRUS-1D model can deal with the change of soil water content caused by nitrogen transformation parameters, HYDRUS-1D model can be well applied to compare the water and nitrogen situation in paddy fields under dry-wet alternate irrigation and long-term flooding irrigation, to evaluate the water and nitrogen balance in paddy fields, and to provide a decision for paddy field water and nitrogen management. (3) The effect of water and fertilizer reuse on regional water saving and agricultural non-point source pollution reduction in the pond and weir system of southern rice irrigation area was studied experimentally. Fully utilizing the storage capacity of the pond weir to collect the returning water from the upstream paddy field and regulate the outflow of the pond weir for the downstream irrigation can also increase the utilization rate of the returning water from the pond weir. The average removal rate of suspended solids was 68.4%. Ammonium nitrogen was the main nitrogen pollutant in the returning water of paddy field, and particulate phosphorus was the main phosphorus pollutant in the returning water. Therefore, the reuse of returning water and nutrients by integrated irrigation ponds and weirs is of great significance to reduce nitrogen and phosphorus emission from farmland and to improve the ecological environment of paddy fields.
【學位授予單位】：武漢大學
【學位級別】：博士
【學位授予年份】：2016
【分類號】：S511
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