渭干河-库车河三角洲绿洲农田表层土壤粒度特征分析

通过野外采样和室内实验相结合,对渭干河-库车河三角洲绿洲农田表层土壤的粒度变化规律及其影响因素进行了深入分析。结果表明:1研究区农田表层土壤机械组成以粉粒和砂粒为主,土壤质地较轻,粘粒和砂粒含量属于弱至中等变异强度;2就各土地利用类型而言,粘粒含量果林地最高,混合作物地最低;粉粒含量混合作物地最高,棉花地最低;砂粒含量棉花地最高,谷物地最低;3各连作年限棉田而言,粘粒含量连作15年棉田最高,连作20年棉田最低;粉粒含量连作15年棉田最高,连作25年棉田最低;砂粒含量连作25年棉田最高,连作15年棉田最低;4从总体上来讲,渭干河、库车河、塔里木河冲洪积物交汇处粘粒和粉粒含量较高,而砂粒含量较低,由绿洲中心往外,以粘粒和粉粒含量逐渐降低,而砂粒含量逐渐增加;5土壤母质属性、地貌地形、气象气候等结构性因素是控制研究区农田表层土壤粒径变异的主要因素,人类的农业生产活动等随机性因素加剧了农田表层土壤粒径的结构变化。

Soil particle size characteristics of farmland topsoils in the Weigan-Kuqa river delta oasis

Combining field sampling and laboratory experiments, we conducted an in-depth analysis on variation of soil particle size of farmland topsoils in a selected study area and the influencing factors. Results show that the main mechanical composition of farmland topsoils were composed of silt and sand. The soils presented a light texture in which clay and sand contents exhibited the weak to moderate variation. For individual land use types, the clay content in the fruit woodland was the highest, while the mixed crop land for the lowest. The silt content in the mixed crop land was the highest, while cotton fields for the lowest. The sand content in the cotton fields was the highest, while the grain crop field for the lowest. For cotton cropping fields, the clay content was shown the highest in the 15-year continuous cropping field, while the lowest in the 20-year continuous cropping field. The silt content was shown the highest in the 15-year continuous cropping field, while the lowest in the 25-year continuous cropping field. The sand content was shown the highest in the 25-year continuous cropping field, while the lowest in the 15-years continuous cropping field. Generally speaking, in the junction of the rivers of Ugan, Kuqa and Tarim with strong alluvial matter exchange, the clay and silt contents were relatively high, while the sand content was low. In the oasis surrounding areas, the clay and silt contents gradually decreased, while the sand content increased. The deterministic factors such as properties of soil parental materials, topography, meteorology and climate were the main factors that control the variation of soil particle size of farmland topsoils in the studied area, while the random factors like human activities for agricultural production intensified the structural changes in the soil particle size of farmland topsoils.