【作者】 冒建华；

【导师】 雷廷武；

【作者基本信息】 西北农林科技大学 ， 水土保持与荒漠化防治， 2003， 硕士

【摘要】 土壤侵蚀的室内模拟实验是目前研究土壤侵蚀问题的有效手段之一，它可为水土保持实践提供科学依据，草地土壤侵蚀的机理和发展变化规律是目前土壤侵蚀研究的重要内容。 现有对于草地覆盖坡地的土壤侵蚀研究多用野外实验取得数据。由于地理条件和天气条件的影响，往往野外实验不能实现长时间多处理的数据的收集，影响实验结果的精度和实验的进度。在坡地水土保持治理过程中，种草护坡需要选用生长快的草种，并能够迅速对坡面形成保护，提高草的出苗率和研究草生长过程中对坡地土壤侵蚀的影响状况更显重要。因此，提出设计一种新型实验仪器，以便准确有效的测定坡地种草后侵蚀率变化状况，而免去长期野外实验的方法。 草地根系可以增强土壤抵抗水流冲刷的能力，有效地减少土壤侵蚀。通过室内实验，研究了集中水流作用下，不同流量和坡度条件下，几种不同草地减少的土壤侵蚀的效果。实验采用3个流量(2，4，8L/min)和5个坡度(5~0，10~0，15~0，20~0，25~0)。所用地面覆盖为，蒿羊矛、黑麦草、苜蓿、裸地(对照)。用试验数据建立了不同流量、不同牧草土壤侵蚀量与坡度间的关系模型。用已建立的模型，比较了几种不同草覆盖的地表相对于裸地减少土壤侵蚀的效果。并在不同生长时期，对三种不同草地进行实验，测定其不同时期的减少侵蚀率变化情况。 通过不同坡度和流量下的统计关系，寻求草地生长期内减少土壤侵蚀的主要因素，并通过分析建立与时间、坡度、流量相关的统计模型。 实验简化在土壤侵蚀模拟与实验中很重要。本次实验由于提出了一种新的实验方法，为了确保实验的精确和可靠，实验次数达720次之多。尚需野外实验对所采取的方法进行检验。 作为一种新型高效土壤改良剂，PAM能够有效地增加土壤团粒结构，减少土壤结皮，改良地表土壤状况，可能有利于作物出苗。本研究采用0，0.5，1.0，1.5，2.0g/m~2的PAM地表处理，通过小区试验，研究了喷灌条件下，PAM对于地表土壤孔隙度的改变并由此带来的对于紫花苜蓿出苗率和出苗整齐度的影响，并且采用了实物图片对照、图表和数据分析的方法，提出了一种有利于北方广大地区种植苜蓿提高出苗率和整齐度的有效途径。 研究得到了提高首楷出苗率和出苗整齐度的经济合理的PAM用量，同时，利用PAM确保在坡地草皮达到有效覆盖前保护坡地。更多还原

【Abstract】 Laboratory simulation experiments are one of the most effective ways to research soil erosion, and lays scientific foundation for soil and water conservation practice. The rule of grassland erosion is an important field in soil erosion.Most of the existing experiments on grassland erosion are in fields. Field experiments are effected by weathers, landforms, social conditions and so on. To collect long-term and complicated deals’ data is much more difficult than laboratory simulation experiments. Fast growing and effective grasses are needed in soil and water conservation on sloping land.A new facility was manufactured to used in the laboratory simulation, and a new experiment way was brought in the simulation experiments.Grass roots reinforce the soil strength withstanding water flow flush and to effectively reduce soil erosion. Laboratory experiments were conducted for the soil erosion reduction under different grasses, as effected by different flow rates and under different slope gradients. 3 flow rates-2, 4 and 8 L/min, 5 slope gradients-5, 10, 15, 20 and 25 degrees as well as 4 surface covers-rye, alfalfa and Tall Fescue and bare soil (control) were used in the experiments. The data of grassland erosion was measured in 5 periods of time in different times of grasses growing periods. Experimental data were used to relate soil erosion with slope gradients of different surface covers under different flow rates in different periods. The models developed were then used to estimate the effectiveness of soil erosion reductions of surface covers as compared with bare surface.PAM, as soil amendment, can effectively stabilize the structure of soil aggregates, reduce soil surface sealing and crusting, improve soil conditions, which might be favorite to seeds’ germination. In this study, field plot experiments, with application rates of PAM of 0, 0.5, 1.0, 1.5 and 2.0 g/m2 were conducted to investigate the impacts of PAM application rates on the porosity ofsoil body and germination rates and time of alfalfa, under sprinkler irrigation. Quantitative analysis showed the soil texture and germination differences under different PAM application rates. Economical PAM application rate for high and even germination rate was suggested.更多还原