Shiraz University Iran Agricultural Research 1013-9885 38 1 2019 10 01 Potassium status of two clayey calcareous soils treated with zeolite under wetting-drying cycles وضعیت پتاسیم دو خاک آهکی رسی تیمار شده با زئولیت و چرخه‌های تری و خشکی 15 22 5296 10.22099/iar.2019.5296 EN M. Najafi-Ghiri Department of Soil Science, College of Agriculture and Natural Resources of Darab, Shiraz University, Darab, I. R. Iran H. R. Owliaie Department of Soil Science, College of Agriculture, Yasouj University, Yasouj, I. R. Iran Journal Article 2016 07 01 Zeolite application to clayey soils may change potassium (K) pools distribution and its release rate. To test this hypothesis, two heavy-textured calcareous soils with different mineralogy (smectitic and mixed by XRD) from southern Iran were selected. Experiment was a completely randomized factorial arrangement. Treatments consisted of two soils and two zeolite levels (0 and 5%) and wetting-drying treatment. Soil samples were incubated in 50% of saturation percentage for 90 days. Then, three wetting-drying cycles were done on samples. Different forms of K and K release to 0.01 M CaCl₂, HCl and CH₃COOH by 12 successive 15 min extractions of soil samples were determined. Zeolite increased the content of different K forms in soil 1 (smectitic), while it increased soluble and exchangeable K and decreased non-exchangeable K in soil 2 (mixed mineralogy). This may be due to the high CEC (189 cmol(+)/kg) and K content (2.13% K₂O) of the used zeolite. Wetting-drying cycles increased non-exchangeable K in soil 1 and exchangeable K in zeolite treated soils. CaCl₂ extracted more K than HCl and CH₃COOH solutions (682, 281 and 292 mg kg^-1, respectively) because Ca ions are more efficient than H ions in replacing K from surface sites in the K-bearing minerals. Zeolite and wetting-drying had no effect on K release from soil 1 while they significantly decreased K release rate from soil 2. https://iar.shirazu.ac.ir/article_5296_6efa5eea15add4d44af0b8168ea9adfd.pdf