Limited information is available on the application of potassium fertilizer in arid and semi-arid soils, because these soils are generally well supplied with plant available potassium. But, soils that have been intensively cropped are becoming depleted in plant available potassium. The objectives of this study were to (i) investigate the effect of potassium fertilizer on the changes in solution and exchangeable potassium and (ii) determine if any of the changes can be attributed to the some physical and chemical property of the soil. Fifteen surface soils were equilibrated at field capacity for three weeks after additions of 0, 21, 42, 104, 208, 415, and 1245 mg K kg-1 of soil. Solution potassium was linearly increased with potassium addition. Also a linear increase in exchangeable potassium with potassium addition was observed. The value of slope representing the proportion of added potassium displaced from exchange sites with ammonium acetate varied from 0.55 to 1.03. Values larger than 1 indicates more exchangeable potassium was displaced from the soil than had been added, whereas values less than 1 shows some fraction of added potassium was fixed into forms that were not extractable with ammonium acetate. The coefficients describing the relation of both solution and exchangeable potassium were not correlated with any of the measured soil properties.

Purpose: To assess the tolerability of potassium Citrate (KCit) tablets in patients with kidney stones that were not able to use the powder form of this drug due to unfavorable salty taste and /or gastrointestinal complications. Materials and Methods: Twenty-three stone formers, with intolerance to potassium citrate powder form, which had referred to Labbafinejad stone preventive clinic in 2015, were included in this study. All of the patients took two potassium citrate tablets (10 meq), three times a day for two weeks. Spot urine samples and the 24-hour urine collections were performed before and after KCit therapy. In addition, a visual analog taste scale was completed to gauge the taste and palatability of the KCit tablets in comparison with the powder form. Results: All of the patients claimed that they consumed the tablets as prescribed. The urine pH (5. 7 ± 0. 6 to 6. 1 ± 0. 8, p = 0. 006), 24-hour citrate (235. 8 ± 190. 2 to 482. 5 ± 323. 2, p = 0. 0002) and potassium (45. 25 ± 22. 5 to 75. 27 ± 37, p = 0. 002) were significantly higher after the treatment. In addition, the mean visual analog scale score was significantly improved in KCit therapy with tablet form versus to powder form of the drug (good vs. terrible score). Conclusion: Oral tolerance of KCit therapy is improved with the use of potassium Citrate tablet, with beneficial effects on 24-hour urine citrate, potassium, and pH.

The leaching of potassium is affected by several factors such as soil texture, concentration of native potassium, amount and velocity of water in the soil and adsorption coefficient. This study was performed for evaluating the effect of soil texture and concentration of native potassium on leaching of potassium in four soil series (Yeknabad, Ahmadabad, Pamas and Hasanabad). The native soil potassium was leached with 10mM of CaCl2 solution. Also, the adsorption isotherm was conducted for evaluating the relationships between the adsorption coefficient and equilibrium concentration of K+ with the losses of potassium in soils. The results showed that after five and twenty pore volumes, the range of K+ leached from the soils were equal to 12-120 and 205-388 kg ha-1, respectively. The adsorption coefficients were in the range of 1.86-5.65 1kg-1. Using linear relationship between the leaching of K+ and the amount of leachate, the rates of potassium leaching were obtained to be in the range of 0.02 to 0.23 kg ha-l mm-l leachate.