本文選題：黑土坡耕地　切入點(diǎn)：苗期玉米　出處：《吉林大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：東北黑土區(qū)面積遼闊、土壤肥沃,是我國(guó)主要的糧食生產(chǎn)基地之一,坡耕地在黑土區(qū)的分布十分廣泛。由于人類長(zhǎng)期不合理的開發(fā)利用以及一些利于土壤侵蝕發(fā)生發(fā)展的自然因素不斷持續(xù)甚至加劇,導(dǎo)致黑土區(qū)坡耕地土壤侵蝕情況十分嚴(yán)重,土壤質(zhì)量連年下降,并引發(fā)大面積的農(nóng)業(yè)非點(diǎn)源污染。因此,研究黑土區(qū)坡耕地的不同耕作措施,尤其是在地表覆蓋較少的玉米苗期保護(hù)性耕作措施的水保效應(yīng)意義重大。為此,本文分析研究了不同降雨條件下黑土區(qū)坡耕地幾種保護(hù)性耕作措施在玉米苗期對(duì)于雨量分配、降雨動(dòng)能分配、降雨前后土壤物理性狀的變化、水土流失以及農(nóng)業(yè)非點(diǎn)源污染物運(yùn)移的影響,揭示了降雨時(shí)不同耕作措施處理的土壤侵蝕和農(nóng)業(yè)非點(diǎn)源污染發(fā)生、發(fā)展過程,并根據(jù)不同需求對(duì)各類耕作措施進(jìn)行了評(píng)價(jià)。主要研究結(jié)論如下：1.苗期玉米本身對(duì)降雨的分配作用并不理想,只能攔截大約6.5%的降雨；冠層郁閉度決定了植株對(duì)降雨的重分配能力,因而在坡耕地上郁閉度較大的順坡／豎壟種植方式可攔截更多的降雨雨量。苗期玉米可以使到達(dá)地表的總體雨滴直徑增大,并降低雨滴動(dòng)能和到達(dá)地表的降雨總能量。秸稈覆蓋可以大幅降低降雨時(shí)的濺蝕速率和擊濺搬運(yùn)速率。2.秸稈覆蓋可基本消除降雨對(duì)于表層土壤容重變化的影響；其他耕作措施條件下,降雨則會(huì)增加土壤容重并將其統(tǒng)一至1.30g/cm2左右。降雨引起的黑土坡耕地上層土壤含水量增量明顯大于下層土壤增量；橫壟和秸稈覆蓋一般會(huì)增加含水量的增長(zhǎng)率。大雨強(qiáng)降雨條件下土壤的水分入滲率高于同等條件下的小雨強(qiáng)降雨；橫壟和秸稈覆蓋處理可以增加降雨時(shí)的水分入滲率,橫壟的效果更加明顯。3.苗期玉米本身的水土保持效應(yīng)并不理想。一般情況下,順壟會(huì)加劇徑流小區(qū)的土壤侵蝕和水土流失情況。秸稈覆蓋和橫壟則會(huì)降低降雨時(shí)的徑流流失速率和土壤流失速率,以及總的徑流量和土壤流失量；但當(dāng)橫壟處理在降雨過程中發(fā)生斷壟時(shí),水、土流失速率均會(huì)在斷壟發(fā)生的一段時(shí)間內(nèi)出現(xiàn)十分明顯的峰值。從保水保土的角度考慮,橫壟+秸稈覆蓋應(yīng)是東北黑土區(qū)坡耕地上苗期玉米的最佳耕作措施選擇。4.徑流中的農(nóng)業(yè)非點(diǎn)源污染物以NH4-N為主,泥沙中則以有機(jī)質(zhì)為主。一般情況下,秸稈覆蓋和橫壟會(huì)增加徑流中污染物的濃度,但會(huì)降低其運(yùn)移總量。秸稈覆蓋會(huì)降低泥沙中的有機(jī)質(zhì)和可溶性PO4-P含量�？傮w而言,橫壟、秸稈覆蓋兩類措施均可有效控制污染物在徑流和泥沙中的運(yùn)移總量。綜合水土保持、土壤性質(zhì)、農(nóng)業(yè)非點(diǎn)源污染等各方面因素考慮,橫壟+秸稈覆蓋為黑土區(qū)坡耕地苗期玉米的最佳耕作措施。
[Abstract]:The Black soil region of Northeast China has a vast area and fertile soil, which is one of the main grain production bases in China. Sloping farmland is widely distributed in black soil area. Because of the long-term unreasonable exploitation and utilization of human being and some natural factors conducive to the occurrence and development of soil erosion, the situation of soil erosion on slope farmland in black soil area is very serious. Soil quality has been declining year after year, and has caused a large area of agricultural non-point source pollution. Therefore, different cultivation measures for sloping farmland in black soil area are studied. The soil conservation effect of conservation tillage measures in maize seedling stage with less surface mulching is of great significance. Therefore, this paper analyzed and studied the rainfall distribution of several conservation tillage measures on slope farmland in black soil area under different rainfall conditions at the seedling stage of maize. The distribution of rainfall kinetic energy, the changes of soil physical properties before and after rainfall, the effects of soil erosion and agricultural non-point source pollutant transport, revealed the occurrence and development process of soil erosion and agricultural non-point source pollution treated by different tillage measures during rainfall. The main conclusions are as follows: 1. The effect of maize at seedling stage on rainfall distribution is not ideal, and only about 6.5% rainfall can be intercepted. Canopy canopy density determines the ability of plant to redistribute rainfall. Therefore, the downhill / vertical ridge planting mode with higher canopy density on sloping farmland can intercept more rainfall, and maize at seedling stage can increase the total raindrop diameter to the surface. And the kinetic energy of raindrop and the total energy of rainfall reached the surface. Straw mulch can significantly reduce the rate of splash erosion and the rate of spatter transport when rainfall falls. Straw mulch can basically eliminate the effect of rainfall on the change of bulk density of surface soil. Under other tillage conditions, rainfall will increase the bulk density of the soil and unify it to 1.30g / cm ~ 2.The increase of soil water content in the upper layer of black soil sloping land is obviously larger than that of the lower soil. The soil moisture infiltration rate under heavy rain was higher than that of light rain under the same condition, and the water infiltration rate under ridge and straw mulching could increase the water infiltration rate under rainfall. The effect of cross ridge is more obvious. 3.The soil and water conservation effect of maize at seedling stage is not ideal. In general, The soil erosion and soil erosion in runoff plot were aggravated by ridge, while straw mulch and cross ridge decreased runoff loss rate and soil loss rate, total runoff and soil loss. However, when ridges break off in the process of rainfall, the water and soil loss rate will appear very obvious peak value in a certain period of time when the ridges are broken off. From the point of view of water and soil conservation, Cross ridge straw mulch should be the best tillage method for maize in seedling stage on sloping farmland in Northeast Black soil area. 4. NH4-N is the main agricultural non-point source pollutant in runoff, and organic matter is the main pollutant in sediment. In general, the agricultural non-point source pollutants in runoff are mainly organic matter. Straw mulching and ridge mulching can increase the concentration of pollutants in runoff, but reduce the total amount of transport. Straw mulching can reduce the content of organic matter and soluble PO4-P in sediment. Straw mulching can effectively control the total amount of pollutants transported in runoff and sediment. The factors such as soil and water conservation, soil properties, agricultural non-point source pollution and so on are considered. Cross ridge straw mulch is the best tillage measure for maize in seedling stage on sloping farmland in black soil area.
【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：S513;S157.4;X71

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