The present paper is aimed at investigating the effects of land use (particularly reducing conditions of paddy fields) on soil structural stability as characterized by the high energy moisture characteristic (HEMC) method and finding the relationship between soil structural stability and available water (AW) in Amol city in Mazandaran province, Iran. Land use conversion led to a change in the soil organic matter (OM) content. The highest OM was found in the forest and pasture land uses, being significantly different from those of citrus garden and paddy field land uses. The high values of bulk density in the citrus garden and paddy fields can be attributed to intensive machinery traffic and puddling, respectively. However, bulk density was low in pasture and forest land uses because of high OM and macropores. Forest and the paddy fields had higher soil structural stability due to high OM/Clay ratio. The HEMC indices including volume of drainable pores ratio (VDPR) and stability ratio (SR) were calculated using the modified van Genuchten model, and the ratio of slopes at the inflection point of HEMCs of fast-wetted to slow-wetted soil samples (S_iR) was determined using the van Genuchten model. The HEMC indices showed positive and significant correlations with OM and OM/Clay ratio. By increasing the OM/Clay ratio, greater clay became complexed with organic matter, and thus soil structure stability increased. A strong correlation was observed between VDPR and OM/Clay in citrus garden and paddy fields. Furthermore, there was a significant correlation between VDPR and AW. The highest field capacity and AW were observed in the forest and paddy fields due to high OM and the presence of smectitic clays under reducing conditions, respectively.

本文旨在研究以高能水分特征（HEMC）法为特征的土地利用（特别是减少水田条件）对土壤结构稳定性的影响，并探讨土壤结构稳定性与可用水量（AW）之间的关系。在伊朗Mazandaran省的Amol市。土地用途的转换导致土壤有机质（OM）含量的变化。在森林和牧场土地利用中发现最高的OM，这与柑桔园和稻田土地利用的显着不同。柑橘园和稻田中堆积密度的高值分别可归因于密集的机械运输和水坑。但是，由于高OM和大孔，在牧场和林地中的堆积密度很低。由于高OM /粘土比，森林和稻田具有较高的土壤结构稳定性。使用改进的van Genuchten模型计算HEMC指数，包括排水孔体积比（VDPR）和稳定性比（SR），以及快速润湿的样品与缓慢润湿的土壤样品的HEMC拐点处的斜率之比（小号_我R）是用求算Van Genuchten模型来确定。HEMC指数与OM和OM / Clay比呈正相关和显着相关。通过增加OM /粘土比，更多的粘土与有机物复合，因此土壤结构稳定性增加。在柑橘园和稻田中，VDPR与OM /粘土之间存在很强的相关性。此外，VDPR和AW之间存在显着的相关性。由于高OM和在还原条件下存在近晶粘土，分别在森林和稻田中观察到了最高的田间持水量和AW。