黑土坡耕地玉米苗期耕作措施对土壤侵蚀和农业非点源污染物运移的影响

发布时间：2018-03-10 18:53

本文选题：黑土坡耕地　切入点：苗期玉米　出处：《吉林大学》2015年硕士论文　论文类型：学位论文

【摘要】：东北黑土区面积辽阔、土壤肥沃,是我国主要的粮食生产基地之一,坡耕地在黑土区的分布十分广泛。由于人类长期不合理的开发利用以及一些利于土壤侵蚀发生发展的自然因素不断持续甚至加剧,导致黑土区坡耕地土壤侵蚀情况十分严重,土壤质量连年下降,并引发大面积的农业非点源污染。因此,研究黑土区坡耕地的不同耕作措施,尤其是在地表覆盖较少的玉米苗期保护性耕作措施的水保效应意义重大。为此,本文分析研究了不同降雨条件下黑土区坡耕地几种保护性耕作措施在玉米苗期对于雨量分配、降雨动能分配、降雨前后土壤物理性状的变化、水土流失以及农业非点源污染物运移的影响,揭示了降雨时不同耕作措施处理的土壤侵蚀和农业非点源污染发生、发展过程,并根据不同需求对各类耕作措施进行了评价。主要研究结论如下：1.苗期玉米本身对降雨的分配作用并不理想,只能拦截大约6.5%的降雨；冠层郁闭度决定了植株对降雨的重分配能力,因而在坡耕地上郁闭度较大的顺坡／竖垄种植方式可拦截更多的降雨雨量。苗期玉米可以使到达地表的总体雨滴直径增大,并降低雨滴动能和到达地表的降雨总能量。秸秆覆盖可以大幅降低降雨时的溅蚀速率和击溅搬运速率。2.秸秆覆盖可基本消除降雨对于表层土壤容重变化的影响；其他耕作措施条件下,降雨则会增加土壤容重并将其统一至1.30g/cm2左右。降雨引起的黑土坡耕地上层土壤含水量增量明显大于下层土壤增量；横垄和秸秆覆盖一般会增加含水量的增长率。大雨强降雨条件下土壤的水分入渗率高于同等条件下的小雨强降雨；横垄和秸秆覆盖处理可以增加降雨时的水分入渗率,横垄的效果更加明显。3.苗期玉米本身的水土保持效应并不理想。一般情况下,顺垄会加剧径流小区的土壤侵蚀和水土流失情况。秸秆覆盖和横垄则会降低降雨时的径流流失速率和土壤流失速率,以及总的径流量和土壤流失量；但当横垄处理在降雨过程中发生断垄时,水、土流失速率均会在断垄发生的一段时间内出现十分明显的峰值。从保水保土的角度考虑,横垄+秸秆覆盖应是东北黑土区坡耕地上苗期玉米的最佳耕作措施选择。4.径流中的农业非点源污染物以NH4-N为主,泥沙中则以有机质为主。一般情况下,秸秆覆盖和横垄会增加径流中污染物的浓度,但会降低其运移总量。秸秆覆盖会降低泥沙中的有机质和可溶性PO4-P含量。总体而言,横垄、秸秆覆盖两类措施均可有效控制污染物在径流和泥沙中的运移总量。综合水土保持、土壤性质、农业非点源污染等各方面因素考虑,横垄+秸秆覆盖为黑土区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.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S513;S157.4;X71

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