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首页> 外文期刊>International Journal of Environmental Research and Public Health >Estimation of the Effect of Soil Texture on Nitrate-Nitrogen Content in Groundwater Using Optical Remote Sensing
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Estimation of the Effect of Soil Texture on Nitrate-Nitrogen Content in Groundwater Using Optical Remote Sensing

机译：利用光学遥感估算土壤质地对地下水硝酸盐氮含量的影响

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The use of chemical fertilizers in Thailand increased exponentially by more than 100-fold from 1961 to 2004. Intensification of agricultural production causes several potential risks to water supplies, especially nitrate-nitrogen (NO3?-N) pollution. Nitrate is considered a potential pollutant because its excess application can move into streams by runoff and into groundwater by leaching. The nitrate concentration in groundwater increases more than 3-fold times after fertilization and it contaminates groundwater as a result of the application of excess fertilizers for a long time. Soil texture refers to the relative proportion of particles of various sizes in a given soil and it affects the water permeability or percolation rate of a soil. Coarser soils have less retention than finer soils, which in the case of NO3?-N allows it to leach into groundwater faster, so there is positive relationship between the percentage of sands and NO3?-N concentration in groundwater wells. This study aimed to estimate the effect of soil texture on NO3?-N content in groundwater. Optical reflectance data obtained by remote sensing was used in this study. Our hypothesis was that the quantity of nitrogen leached into groundwater through loam was higher than through clay. Nakhon Pathom province, Thailand, was selected as a study area where the terrain is mostly represented by a flat topography. It was found that classified LANDSAT images delineated paddy fields as covering 29.4% of the study area, while sugarcane covered 10.4%, and 60.2% was represented by “others”. The reason for this classified landuse was to determine additional factors, such as vegetation, which might directly affect the quantity of NO3?-N in soil. Ideally, bare soil would be used as a test site, but in fact, no such places were available in Thailand. This led to an indirect method to estimate NO3?-N on various soil textures. Through experimentation, it was found that NO3?-N measured through the loam in sugarcane (I = 0.0054, p < 0.05) was lower than clay represented by paddies (I = 0.0305, p < 0.05). This had a significant negative impact on the assumption. According to the research and local statistical data, farmers have always applied an excess quantity of fertilizer on paddy fields. This is the main reason for the higher quantity of NO3?-N found in clay than loam in this study. This case might be an exceptional study in terms of quantity of fertilizers applied to agricultural fields.
机译：从1961年到2004年，泰国化学肥料的使用呈指数增长，增长了100倍以上。农业生产的集约化对水供应造成若干潜在风险，尤其是硝酸盐氮（NO3？-N）污染。硝酸盐被认为是潜在的污染物，因为其过量使用会通过径流流入溪流，并通过淋滤进入地下水。施肥后，地下水中的硝酸盐浓度增加了3倍以上，并且由于长期施用过量肥料而污染了地下水。土壤质地是指给定土壤中各种尺寸颗粒的相对比例，它会影响土壤的透水性或渗透率。较粗的土壤比较细的土壤具有更少的保留力，在NO3？-N的情况下，粗土壤的浸提速度更快，因此，沙子的百分比与地下水井中的NO3？-N浓度之间存在正相关关系。这项研究旨在评估土壤质地对地下水中NO3？-N含量的影响。通过遥感获得的光反射率数据用于这项研究。我们的假设是，通过壤土淋溶到地下水中的氮的量高于通过黏土渗出的氮。泰国佛统府被选为研究区域，那里的地形主要由平坦的地形表示。结果发现，分类的LANDSAT图像描绘出的稻田覆盖了研究区域的29.4％，而甘蔗覆盖了10.4％，其中60.2％由“其他”代表。进行土地分类的原因是要确定其他因素，例如植被，这些因素可能直接影响土壤中NO3？-N的含量。理想情况下，将裸露的土壤用作测试场所，但实际上，泰国没有此类场所。这导致了一种间接方法来估算各种土壤质地上的NO 3 -N。通过实验发现，通过甘蔗中的壤土测量的NO 3 -N（I = 0.0054，p <0.05）低于以稻田为代表的粘土（I = 0.0305，p <0.05）。这对假设产生了重大的负面影响。根据研究和当地统计数据，农民一直在稻田上施用过量的肥料。这是本研究中粘土中发现的NO3α-N含量高于壤土的主要原因。就施用于农业领域的肥料数量而言，这种情况可能是一个例外的研究。

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