[目的]土壤磁化率是环境污染监测领域的常用参数,一般在裸土表面测量.农田土壤通常覆盖有作物秸秆,本文主要研究作物秸秆覆盖对农田土壤磁化率测量的影响.[方法]在水稻田、甘蔗地1、甘蔗地2和玉米地4块试验田分别设置测量点并人为均匀叠加秸秆,测量不同秸秆材质和覆盖厚度下农田土壤磁化率,分析秸秆覆盖对农田土壤磁化率测量的影响.[结果]随秸秆覆盖厚度的增加土壤磁化率不断减小,当厚度在0～5 cm时,磁化率测量值迅速衰减,但其值可在一定程度上反映裸土磁化率;当厚度超过6 cm时,磁化率测量值衰减趋缓;当超过10 cm时,磁化率测量值趋于0.试验中大部分测量点数据可用指数模型拟合,少数测量点用线性模型拟合.分别整合水稻田、甘蔗地1、甘蔗地2和玉米地所有测量点的数据,土壤磁化率与秸秆覆盖厚度之间分别表现为指数、指数、指数和线性负相关.不同秸秆覆盖厚度所对应的检测距离是造成土壤磁化率测量值衰减的主要因素,秸秆本身材质对测量值影响很小.[结论]利用MS2D型磁化率仪测量农田土壤磁化率时,最好直接对裸土进行测量,如果有秸秆覆盖,覆盖厚度不宜超过5 cm.秸秆覆盖厚度对土壤磁化率测量值的影响可用指数或线性负相关函数模型表征.%[Objective]The soil magnetic susceptibility is a common parameter for monitoring environmental pollution,and usually measured on the surface of bare soil.The farmland soil is often covered with crop straw,and this paper mainly studies the influence of straw mulching on farmland soil magnetic susceptibility measurement.[Method]The measuring points were set in paddy field,sugarcane field 1,sugarcane field 2 and corn field respectively,and piled up with straws artificially and evenly.The soil magnetic susceptibility values were measured under different straw materials and straw mulching thicknesses to analyze the influence of straw mulching on farmland soil magnetic susceptibility measurement.[Result]The soil magnetic susceptibilities decreased constantly with the increase of straw mulching thickness.When the thicknesses ranged from 0 to 5 cm,soil magnetic susceptibilities attenuated rapidly,but the values could reflect the magnetic susceptibility of bare soil to a certain extent.When the thicknesses exceeded 6 cm,soil magnetic susceptibilities attenuated slowly and when the thicknesses exceeded 10 cm,soil magnetic susceptibilities tended to zero.The test data of most measuring points were fitted with index model,while that of a few points were fitted with linear model.Data of all measuring points in paddy field,sugarcane field 1,sugarcane field 2 and corn field were respectively integrated,and the relationships between soil magnetic susceptibility and straw mulching thickness in above fields were characterized by index,index,index and linear negative correlations.The corresponding detection distances of different straw mulching thicknesses were the main factors causing the attenuation of soil magnetization susceptibilities,and the influences of straw materials on the measured value were very small.[Conclusion]When measuring soil magnetic susceptibility with MS2D magnetic susceptibility meter,it is best to measure bare soil directly.If there is straw mulching,the mulching thickness should not exceed 5 cm.The influence of straw mulching thickness on soil magnetic susceptibility can be characterized by index function or linear negative correction model.
展开▼
