عنوان مقاله [English]
Soil physico-chemical properties and management practices are important to balance different forms of potassium. This study was carried out to compare different land use effects on spatial variability of available and total potassium and to investigate the relationships between available and total potassium with soil characteristics in selected soils of Mazandaran province. A total of 258 composite surface soil samples (0-10 cm) were taken from an area of about 5500 km2 using a systematic sampling scheme. Also 5 profiles located in different land uses were studied. The amounts of available and total potassium in each soil sample were determined. Some soil properties including pH, calcium carbonate equivalent, organic matter, cation exchange capacity and particle size distribution were also measured. The results showed that surface and profile distribution of available potassium is controlled by factors affecting the potassium availability and subsequently, management and land use. Total potassium is affected by inherent factors such as parent materials. The concentration of available potassium was higher in pasture soil samples with high potassium-bearing primary minerals, organic matter and cation exchange capacity. Indicator kriging was used to estimate the potassium deficient areas. Probability map showed that soil available potassium is below the critical limit for rice cropping in an area of about 700 km2, with a probability of more than 60 percent. The low values of available potassium can be attributed to long term intensive rice cropping without K-fertilization.