砒砂岩与沙复配土壤质地与有机质动态变化特征

Dynamic Change Characteristics of Texture and Organic Matter Content of Soft Rock and Sand Compound Soil in Mu Us Sandy Land

为了研究毛乌素沙地砒砂岩与沙混合构成的一种新型复配土壤在长期种植过程中土壤质量发育状况,基于2010-2018年不同比例砒砂岩与沙(1∶1,1∶2,1∶5)复配土壤的田间定位试验,综合分析了不同比例复配土壤机械组成、颗粒分形特征、有机质的变化特征及之间的关系。结果表明:(1)随着种植年限的增加,3种比例复配土壤耕层质地向变细和颗粒组成合理的方向发展,土壤颗粒分形维数和有机质含量总体呈增加趋势;(2)1∶2复配土壤粉黏粒含量、分形维数值和有机质含量增加速率均大于1∶1,1∶5;1∶2复配土壤种植9年后有机质含量达到最高值(6.24±0.30)g/kg,与种植前相比较提高了12倍;(3)不同比例复配土壤颗粒分形维数与有机质含量均存在显著正相关关系(p<0.05),粉粒和黏粒是研究区沙化土地复配土壤质地改善和有机质提升最关键的两个粒级。综上,随种植年限的增加,复配土向无机-有机胶体复合状态发展,1∶2复配土壤最适合玉米种植,提高了土壤的稳定性和农业适应性。

In order to study the soil quality development status of a new type of mixed composite soil of soft rock and sand in the Mu Us sandy land during the long-term planting process,based on the field positioning test of different proportions of soft rock and sand compound soil(1∶1,1∶2,1∶5)from 2010 to 2018,the change characteristics of soil mechanical composition,particle fractal dimension and organic matter content and the relationship between them were comprehensively analyzed.The results show that:with the increase of planting years,the textures of cultivated layer of the three proportion compound soils have become thinner and better;the particles fractal dimension and organic matter content of compound soil generally showed an increasing trend,among which the increase rates of 1∶2 compound soil silt and clay content,fractal dimension value and organic matter content were all greater than 1∶1 and 1∶5;the organic matter content of the 1∶2 compound soil reached the highest value(6.24±0.30 g/kg)after nine years,which was 12 times higher than that before planting;there was a significant positive correlation between the fractal dimension and the organic matter content of compound soil in different proportions(p<0.05),silt and clay are the two most critical grain sizes for the improvement of compound soil texture and organic matter in the study area;the 1∶2 ratio compound soil was determined to be most suitable for maize cultivation,as it best developed a composite state of inorganic and organic colloids that improved the soil stability and subsequent agricultural suitability.