再生水地下滴灌對土壤酶活性和大腸桿菌（Escherichia coli）遷移的影響
發(fā)布時間：2018-09-18 09:34
【摘要】：滴灌是應用再生水最適宜的灌溉方式,能夠避免直接接觸污染和減少污染物隨地表徑流遷移,但是再生水中含有相對較高的鹽分、養(yǎng)分、溶解性有機質和病原體等物質,且再生水滴灌可能增加根區(qū)土壤鹽分和養(yǎng)分含量以及病原體濃度,影響根區(qū)土壤養(yǎng)分轉化和生物活性,進而增加養(yǎng)分淋失、病原體淋溶污染地下水的風險。因此,研究再生水滴灌條件下灌水量和滴灌帶埋深對土壤酶活性、大腸桿菌-Escherichia coli(E.coli)分布和水氮淋失的影響對再生水安全高效灌溉具有重要的理論和實踐指導意義。本文以玉米(Zea mays L.)為研究對象,于2014和2015年在華北平原半濕潤地區(qū)(北京大興)開展再生水地下滴灌大田玉米試驗。試驗因素包括灌水量、滴灌帶埋深和灌溉水質3個因素。其中,灌水量按作物需水量(ETC)的70%(I1)、100%(I2)和130%(I3)設置3個水平;滴灌帶埋深設為0 cm(D1)、15 cm(D2)和30 cm(D3)3個水平;此外,將地下水灌溉設置為對照處理(2014年地下水對照灌水量為12;2015年地下水對照灌水量為I3),對照處理滴灌帶埋深分別為0、15和30 cm,記為C1、C2和C3。玉米生育期內(nèi)監(jiān)測了土壤酶活性(堿性磷酸酶、脲酶和蔗糖酶)、E.coli分布、水氮動態(tài)、NO33--N淋失特征、土壤電導率(ECb)和化學性質,并在關鍵生育階段測定了植株株高、葉面積指數(shù)(LAI)和葉、莖、籽粒干物質質量以及吸氮量,分析了滴灌帶埋深、灌水量和灌溉水質對土壤酶活性、E.coli分布與運移、土壤水氮分布與淋失、土壤鹽分、玉米生長和產(chǎn)量的影響。為了更系統(tǒng)地定量評價施肥制度對再生水虧缺灌溉條件下淺滴灌帶埋深處理(I1D2)硝態(tài)氮淋失的影響,基于HYDRUS-2D軟件構建了地下滴灌水氮運移模型,并模擬分析了施氮量對再生水虧缺灌溉條件下淺滴灌帶埋深處理硝態(tài)氮淋失的影響。主要結論如下:(1)再生水地下滴灌條件下,0～20 cm深度土壤含水率隨灌水量增加而顯著增加,隨滴灌帶埋深增加而顯著減小;較大灌水量和滴灌帶埋深均會導致NO_3~--N向下層土壤運移,增大NO_3~--N淋失風險。與地下水灌溉相比,再生水灌溉增加了土壤NO_3~-N含量而降低了土壤NH4+-N含量。灌溉后表層土壤ECb增幅以較低滴灌帶埋深處理較高,而隨著土壤深度增加,ECb增幅隨滴灌帶埋深呈增加趨勢。兩年試驗中,再生水灌溉明顯提高了 0～50 cm深度土壤ECb,但是不會導致土壤鹽漬化。(2)再生水地面灌和滴灌后堿性磷酸酶、脲酶和蔗糖酶活性在土壤剖面均呈層狀分布。較小的滴灌帶埋深明顯提高了表層土壤酶活性,較大的滴灌帶埋深顯著促進了深層土壤酶活性;與滴灌帶埋深相比,灌水量對土壤酶活性的影響隨土壤深度、生育階段和酶活性類型而變化。相關分析結果表明:灌溉處理前后堿性磷酸酶、脲酶和蔗糖酶活性與土壤有機質、全氮、全磷和pH顯著相關,不同類型酶活性對灌溉施肥管理響應一致;脲酶活性在玉米生育前期促進尿素水解和氮素礦化,后期促進氮素吸收和生物固持。與地下水滴灌相似,再生水地下滴灌提高了根區(qū)土壤酶活性,沒有干擾和改變土壤C、N、P養(yǎng)分轉化,不會對土壤肥力水平造成負面影響。(3)再生水地下滴灌不會導致玉米生育期E.coli在土壤中累積,E.coli不會隨深層滲漏進入深層土壤。水分深層滲漏主要發(fā)生在降雨較大而作物耗水量較小的生育初期和末期。滴灌條件下較大的灌水量和滴灌帶埋深均會增加深層滲漏風險和導致土壤溶液中較高的NO_3~-N濃度;玉米生育期累積NO_3~-N淋失量隨滴灌帶埋深增加而顯著增加。與地下水滴灌相比,再生水滴灌明顯增加了 NO_3~--N淋失量,2014和2015年平均增加幅度分別為65%和84%。(4)灌水量和滴灌帶埋深均未顯著影響玉米產(chǎn)量及其構成要素。與地下水滴灌相比,再生水滴灌未對玉米株高、LAI、地上部分干物質質量及吸氮量、產(chǎn)量及其構成要素和品質造成顯著差異;同時,再生水滴灌未造成玉米籽粒E.coli污染�？紤]節(jié)水、玉米產(chǎn)量和根區(qū)水氮淋失,華北平原半濕潤地區(qū)滴灌條件下玉米生育期內(nèi)采用灌水量為70%ETC較為適宜。(5)基于HYDRUS-2D軟件建立了地下滴灌線源土壤水分、NO_3~--N和NH4+-N運移模型,評估了施氮量及其分配對NO_3~--N淋失的影響。模擬結果表明:玉米生育期累積NO_3~--N淋失量隨施氮量增加而增加。綜上所述,滴灌帶埋深15 cm的地下滴灌結合70%ETC灌溉能夠提高作物根區(qū)土壤酶活性,避免再生水直接接觸污染和E.coli在土壤中累積,同時降低水氮淋失,并維持較高的玉米產(chǎn)量,是華北平原半濕潤地區(qū)大田玉米較合適的再生水灌溉管理方式。
[Abstract]:Drip irrigation is the most suitable irrigation method for reclaimed water, which can avoid direct contact with pollution and reduce pollutant migration with surface runoff. However, reclaimed water contains relatively high salinity, nutrients, dissolved organic matter and pathogens, and reclaimed water drip irrigation may increase soil salinity and nutrient content and pathogen concentration in root zone. Therefore, it is necessary to study the effects of irrigation quantity and buried depth of drip irrigation zone on soil enzyme activity, distribution of E. coli and leaching of water and nitrogen on safe and efficient irrigation of reclaimed water. In this paper, a field experiment of reclaimed water subsurface drip irrigation on Maize (Zea mays L.) was carried out in the semi-humid area of North China Plain (Daxing, Beijing) in 2014 and 2015. The experimental factors include irrigation quantity, buried depth of drip irrigation zone and irrigation water quality. Among them, irrigation quantity is based on crop water requirement (ETC). Three levels were set up for 70% (I1), 100% (I2) and 130% (I3); the buried depth of drip irrigation belt was 0 cm (D1), 15 cm (D2) and 30 cm (D3); in addition, groundwater irrigation was set as the control treatment (groundwater control irrigation in 2014 was 12; groundwater control irrigation in 2015 was I3), and the buried depth of drip irrigation belt was 0, 15 and 30 cm respectively, which was recorded as C1, C2 and C3. Soil enzyme activities (alkaline phosphatase, urease and sucrase), E.coli distribution, water and nitrogen dynamics, NO33-N leaching characteristics, soil electrical conductivity (ECb) and chemical properties were monitored during rice growth period. Plant height, leaf area index (LAI), leaf, stem and grain dry matter quality and nitrogen uptake were measured at key growth stages. Effects of irrigation quantity and irrigation water quality on soil enzyme activity, E.coli distribution and movement, soil water and nitrogen distribution and leaching, soil salinity, maize growth and yield were studied. The main conclusions are as follows: (1) Under the condition of subsurface drip irrigation with reclaimed water, the soil moisture content at 0-20 cm depth increases significantly with the increase of irrigation amount, and decreases significantly with the increase of the depth of the drip irrigation zone. Compared with groundwater irrigation, reclaimed water irrigation increased the content of soil NO_3~-N and decreased the content of soil NH4 +-N. After irrigation, the increase of ECb in surface soil was higher at lower depth of drip irrigation, but with the increase of soil depth, ECb increased. In the two-year experiment, the soil ECb of 0-50 cm depth was significantly increased by reclaimed water irrigation, but soil salinization was not observed. (2) Alkaline phosphatase, urease and invertase activities were stratified in soil profiles after surface and drip irrigation. The results showed that the soil enzyme activities were significantly promoted by the deeper buried depth of drip irrigation zone, and the effects of irrigation amount on soil enzyme activities varied with soil depth, growth stage and enzyme activity types. Nitrogen, total phosphorus and pH were significantly correlated, and the responses of different enzyme activities to irrigation and fertilization management were consistent. Urease activity promoted urea hydrolysis and nitrogen mineralization in early growth stage, and nitrogen absorption and biological fixation in late growth stage of maize. Nutrient transformation had no negative effect on soil fertility. (3) Subsurface drip irrigation with reclaimed water did not cause E. coli accumulation in soil during maize growth period, and E. coli did not enter deep soil with deep leakage. Compared with drip irrigation, drip irrigation with reclaimed water significantly increased the leaching loss of NO_3-N, with an average increase of 65% in 2014 and 2015, respectively. (4) Compared with drip irrigation, there was no significant difference in plant height, LAI, aboveground dry matter quality, nitrogen uptake, yield, components and quality of maize, and there was no significant difference in E. coli pollution. Considering water saving, maize yield and root water and nitrogen leaching loss, 70% ETC was more suitable for maize growth period under drip irrigation in semi-humid area of North China Plain. (5) Based on HYDRUS-2D software, soil moisture, NO_3~--N and NH4 + - N transport models of subsurface drip irrigation line source were established, and the effects of nitrogen application and its distribution on NO_3~--N leaching were evaluated. The results showed that the accumulation of NO_3~--N leaching increased with the increase of nitrogen application. In conclusion, the combination of subsurface drip irrigation with 70% ETC irrigation at a depth of 15 cm in drip irrigation zone could improve soil enzyme activity in crop root zone, avoid the direct contact of reclaimed water with pollution and the accumulation of E.coli in soil, reduce water and nitrogen leaching, and maintain higher maize yield. Yield is a suitable management mode of reclaimed water for field corn in semi humid area of North China Plain.
【學位授予單位】：中國水利水電科學研究院
【學位級別】：博士
【學位授予年份】：2017
【分類號】：S275.6;S154
本文編號：2247501
[Abstract]:Drip irrigation is the most suitable irrigation method for reclaimed water, which can avoid direct contact with pollution and reduce pollutant migration with surface runoff. However, reclaimed water contains relatively high salinity, nutrients, dissolved organic matter and pathogens, and reclaimed water drip irrigation may increase soil salinity and nutrient content and pathogen concentration in root zone. Therefore, it is necessary to study the effects of irrigation quantity and buried depth of drip irrigation zone on soil enzyme activity, distribution of E. coli and leaching of water and nitrogen on safe and efficient irrigation of reclaimed water. In this paper, a field experiment of reclaimed water subsurface drip irrigation on Maize (Zea mays L.) was carried out in the semi-humid area of North China Plain (Daxing, Beijing) in 2014 and 2015. The experimental factors include irrigation quantity, buried depth of drip irrigation zone and irrigation water quality. Among them, irrigation quantity is based on crop water requirement (ETC). Three levels were set up for 70% (I1), 100% (I2) and 130% (I3); the buried depth of drip irrigation belt was 0 cm (D1), 15 cm (D2) and 30 cm (D3); in addition, groundwater irrigation was set as the control treatment (groundwater control irrigation in 2014 was 12; groundwater control irrigation in 2015 was I3), and the buried depth of drip irrigation belt was 0, 15 and 30 cm respectively, which was recorded as C1, C2 and C3. Soil enzyme activities (alkaline phosphatase, urease and sucrase), E.coli distribution, water and nitrogen dynamics, NO33-N leaching characteristics, soil electrical conductivity (ECb) and chemical properties were monitored during rice growth period. Plant height, leaf area index (LAI), leaf, stem and grain dry matter quality and nitrogen uptake were measured at key growth stages. Effects of irrigation quantity and irrigation water quality on soil enzyme activity, E.coli distribution and movement, soil water and nitrogen distribution and leaching, soil salinity, maize growth and yield were studied. The main conclusions are as follows: (1) Under the condition of subsurface drip irrigation with reclaimed water, the soil moisture content at 0-20 cm depth increases significantly with the increase of irrigation amount, and decreases significantly with the increase of the depth of the drip irrigation zone. Compared with groundwater irrigation, reclaimed water irrigation increased the content of soil NO_3~-N and decreased the content of soil NH4 +-N. After irrigation, the increase of ECb in surface soil was higher at lower depth of drip irrigation, but with the increase of soil depth, ECb increased. In the two-year experiment, the soil ECb of 0-50 cm depth was significantly increased by reclaimed water irrigation, but soil salinization was not observed. (2) Alkaline phosphatase, urease and invertase activities were stratified in soil profiles after surface and drip irrigation. The results showed that the soil enzyme activities were significantly promoted by the deeper buried depth of drip irrigation zone, and the effects of irrigation amount on soil enzyme activities varied with soil depth, growth stage and enzyme activity types. Nitrogen, total phosphorus and pH were significantly correlated, and the responses of different enzyme activities to irrigation and fertilization management were consistent. Urease activity promoted urea hydrolysis and nitrogen mineralization in early growth stage, and nitrogen absorption and biological fixation in late growth stage of maize. Nutrient transformation had no negative effect on soil fertility. (3) Subsurface drip irrigation with reclaimed water did not cause E. coli accumulation in soil during maize growth period, and E. coli did not enter deep soil with deep leakage. Compared with drip irrigation, drip irrigation with reclaimed water significantly increased the leaching loss of NO_3-N, with an average increase of 65% in 2014 and 2015, respectively. (4) Compared with drip irrigation, there was no significant difference in plant height, LAI, aboveground dry matter quality, nitrogen uptake, yield, components and quality of maize, and there was no significant difference in E. coli pollution. Considering water saving, maize yield and root water and nitrogen leaching loss, 70% ETC was more suitable for maize growth period under drip irrigation in semi-humid area of North China Plain. (5) Based on HYDRUS-2D software, soil moisture, NO_3~--N and NH4 + - N transport models of subsurface drip irrigation line source were established, and the effects of nitrogen application and its distribution on NO_3~--N leaching were evaluated. The results showed that the accumulation of NO_3~--N leaching increased with the increase of nitrogen application. In conclusion, the combination of subsurface drip irrigation with 70% ETC irrigation at a depth of 15 cm in drip irrigation zone could improve soil enzyme activity in crop root zone, avoid the direct contact of reclaimed water with pollution and the accumulation of E.coli in soil, reduce water and nitrogen leaching, and maintain higher maize yield. Yield is a suitable management mode of reclaimed water for field corn in semi humid area of North China Plain.
【學位授予單位】：中國水利水電科學研究院
【學位級別】：博士
【學位授予年份】：2017
【分類號】：S275.6;S154
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