农业工程学报2019，Vol.35Issue(17)：154-161,8.DOI:10.11975/j.issn.1002-6819.2019.17.019
砒砂岩区小流域土壤有机质空间分布特征及其影响因素
Spatial distribution characteristics of soil organic matter and its influencing factors in small watershed of feldspathic sandstone region
摘要
Abstract
The feldspathic sandstone region in middle reach of Yellow river is the main origin of course sand eroded to the river. It features with complex and diverse landforms characterized by ravines and gullies criss-cross, and is a key region for implementing the soil-water conservation and ecological restoration program in China. Since soil organic matter (SOM) plays an important role in almost all physical and biochemical processes in soil, understanding the spatial distribution of SOM is imperative to guide vegetation construction and reduce erosion of coarse sand into Yellow River. The Baojiagou small watershed, with an area of 12.67 km2, is a representative watershed in the Feldspathic sandstone region. It has been kept uninhabited and off anthrophonic effect in the test of an ecological immigration policy. Survey results reveal that forest and grassland are the main land use in the watershed. In this research, we analyzed SOM by sampling soils from a grid network in a plot in July 2018. Soil samples were taken from the depths of 0-20, 20-40 and 40-60 cm from each grid in the plot, and the SOM content in them was analyzed using sulfate digestion method. Soil potassium, dichromate and mechanical composition were measured by laser particle-size analyzer, and vegetation coverage was analyzed using photographic measurement. The spatial distribution of SOM and its dependence on environmental and topographical factors were analyzed using geo-statistics and the constrained ordination respectively. The results show that SOM content varied from 0.98 to 15.45 g/kg, and its dependence on topographic factors was ranked in the order of valley floor>slope> ridge. The semi-variance of SOM can be fitted by an exponential function, with its spatial variability being at medium level and the nugget effect ranging from 55.1 % to 57.5 %. SOM was rich in the center of the plot. Redundancy analysis (RDA) showed that the first and second axis explained 96.1% and 2. 8% of the total variation of SOM, respectively, and the first two axes explained 99.3% of the relationship between SOM and environmental factors. The correlation coefficient of SOM to the environmental factors in the first axis was ranked in the order of vegetation coverage > soil erosion degree > soil particle diameter > slope position > elevation > slope. Vegetation coverage and soil erosion degree correlated to SOM most closely with the first ranking axis defined as the vegetation-soil erosion factor. The slope has the largest correlation coefficient with the second ranking axis, which was defined as slope factor. Vegetation coverage was the dominant factor affecting the spatial distribution of SOM, and soil erosion degree was the main factor impacting the vertical distribution of SOM in the feldspathic sandstone region. Our results suggest that the areas with shallow soil are not suitable for large-scale land preparation and afforestation, and that surface sealing works better for these areas. Gully areas with deep soil and good water and soil fertility are suitable for planting trees.关键词
土壤/有机质/砒砂岩区/空间分布特征/约束性排序/影响因素Key words
soils/organic matter/feldspathic sandstone region/spatial distribution characteristics/constrained ordination/influencing factors分类
农业科技引用本文复制引用
杨振奇,秦富仓,李龙,任小同,钱秋颖,韩君..砒砂岩区小流域土壤有机质空间分布特征及其影响因素[J].农业工程学报,2019,35(17):154-161,8.基金项目
内蒙古自治区研究生教育创新计划项目(B2018111939Z) （B2018111939Z）
2018内蒙古科技计划项目,"黄河粗沙集中来源区典型流域生态修复技术体系研究" （）
国家自然科学基金青年基金项目(41807079) （41807079）
