摘要
随着地膜的大规模连续使用,农膜残留随之剧增,从而破坏了原有土壤结构,改变了土壤水分入渗及持水性能,严重阻碍了土壤水分和溶质运移。饱和导水率和土壤水分特征曲线是表征水分入渗性能及进行水分和溶质运移的重要参数,为了定量化和可视化残膜对水力特性及土壤结构的影响规律,通过设置5个残膜量处理(0、5、100、200、400 kg/hm2),利用室内试验研究了不同残膜量对水分入渗及土壤持水性能的影响,并基于CT扫描技术分析残膜对土壤结构的影响效应。结果显示:随着残膜量增加,饱和导水率呈显著指数下降趋势(p<0.05),当残膜量达到200 kg/hm2时,饱和导水率仅为无膜处理的12%。在高吸力阶段(>100 k Pa),残膜量增加土壤反而越易脱水,持水性能反而变差,即特征曲线左移;基于van Genuchten模型和Gardner模型对不同残膜量处理的吸力和土壤含水率进行拟合,精度均较高,模型中经验参数随残膜量增加均呈明显规律变化。当残膜量增加后,二值化后的CT图像显示片状黑斑面积明显增加,并与残膜量呈比例关系,其中400 kg/hm2处理黑斑面积是无膜处理的19倍。
The residual of plastic film in soil continuously increased with the large application of agricultural plastic film during the last few decades. It destroyed the soil structure and seriously influenced the migration of soil water movement and solute. Saturated hydraulic conductivity and soil water characteristic curve are very important parameters for evaluating infiltration properties and simulating soil water and solute. Five residual film treatments （ 0, 5,100,200,400 kg/hm2 ） were conducted to study the effects of different amounts of residual film on soil water infiltration and soil water retention ability and also to analyze the influences of residual film on soil structure based on CT images. The results showed that saturated hydraulic conductivity was significantly exponentially decreased with increase of residual film （p 〈 0.05 ）. When residual film reached 200 kg/hm：, the saturated hydraulic conductivity reduced to 12% of non-residual film treatment. However, the soil was easily dehydrated and water retention ability was lowered with increase of residual film under high suction condition （ 〉 100 kPa）. There were good relationships between suction and soil water based on either van Genuchten model or Gardner model, and the parameters showed regular variation with the increase of residual film. The threshold CT images showed that black spot area clearly increased with the increase of residual film, and there was proportional relation between black spot area and residual film amount. The black spot areas were 19 times than non-residual film treatment, and the residual film significantly increased in soil.
出处
《农业机械学报》
EI
CAS
CSCD
北大核心
2015年第5期101-106,140,共7页
Transactions of the Chinese Society for Agricultural Machinery
基金
国家自然科学基金资助项目(51349003
51469022)
中国水利水电科学研究院重点实验室开放基金资助项目(IWHR-SKL-201118)
内蒙古自治区自然科学基金资助项目(2011BS0302)
关键词
残膜
饱和导水率
土壤水分特征曲线
土壤结构
CT
Residual plastic film Saturated hydraulic conductivity Soil water characteristic curveSoil structure CT
