Abstract—

Experiments were conducted for thirty representative surface and subsurface soils collected from different physiographic units and moisture regimes in southern Iran to assess factors affecting K pools distribution and potassium release rate, using two organic and inorganic extractants and their association to mineralogy and some physical and chemical properties in calcareous soils. Mineralogical analysis indicated that illite, smectite, chlorite and palygorskite were the main clay minerals in the studied soils. The highest content of illite and smectite was observed in the piedmont plain (P.P) units, whereas that of smectite in Lowland (L.L) unit was higher than in soils of alluvial fans (A.F). It seems that the P.P unit which is in more stable landform position contains larger amounts of all K compounds due to higher clay and illite contents. The exchangeable, non-exchangeable (NEK), structural, and total potassium were found to be significantly and positively correlated to the clay content, cation exchange capacity, and the contents of illite, smectite, and vermiculite minerals, while a negative correlation as observed between the mentioned K forms and the calcium carbonate (CaCO₃) content. The cumulative rate of K release to 0.01 M CaCl₂ and oxalic acid was examined for a period of 1200 h, ranging within 104–286 and 87–233 mg kg^–1 for the surface soil and 98–241 and 82–211 mg kg^–1 for the subsurface soil samples, respectively. The percentage of non-exchangeable K released varied greatly between the different units and moisture regimes. Higher values of NEK release were observed for P.P followed by A.F, and L.L units. Considering the obtained values of the highest amount of potassium compounds as well as the release values in the piedmont plain physiographic unit and the xeric moisture regime as well as the Alfisols, the results confirm that in addition to physicochemical and mineralogical properties, physiographic units and soil moisture regimes also play a key role in nature and in spatial distribution of different forms of potassium.

中文翻译：

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伊朗南部法尔斯省气候条件，生理单位和某些理化特性对某些石灰性土壤钾库分布的影响

摘要-

使用两种有机和无机萃取剂及其与矿物学和某些理化性质的关系，对伊朗南部从不同生理单位和水分状况收集的三十种代表性表层和地下土壤进行了实验，以评估影响钾库分布和钾释放速率的因素。在石灰质土壤中。矿物学分析表明，伊利石，蒙脱石，绿泥石和坡缕石是研究土壤中的主要粘土矿物。在山前平原（PP）单元中观察到伊利石和蒙脱石的含量最高，而在低地（LL）单元中的蒙脱石的含量高于冲积扇（AF）的土壤中。由于较高的粘土和伊利石含量，处于更稳定地貌位置的PP单元似乎包含大量的所有K化合物。₃）内容。在1200 h内检查了K释放至0.01 M CaCl ₂和草酸的累积速率，表层土壤的K释放量在104–286和87–233 mg kg ^–1之间，98–241和82–211 mg kg ^–1分别用于地下土壤样品。不可交换的钾释放百分比在不同的单位和水分制度之间差异很大。PP，AF和LL单位的NEK释放值较高。考虑到所获得的钾化合物的最高含量值，山前平原生理学单位和干湿状况以及铝水溶胶的释放值，结果证实，除了理化和矿物学性质外，生理学单位和土壤水分状况在自然界和不同形式钾的空间分布中也起着关键作用。