الفهرس 
Mineral Potassium Fertilizers.
Controlled or slow-release K-fertilizer sources:Only 14 pages are availabe for public view
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Abstract
Three experiments were conducted; the first experiment of them was conducted in soil laboratory to study the behaviors of the different forms of potassium sulphate fertilizer. The other two experiments of them (second and third) were conducted at field during growing seasons of 2005/2006 and 2006/2007 on potato (Solanum tuberosum, L.) cultivar Draga to evaluate the effect soil and foliar K application in different forms with FYM on growth, yield, quality, chemical composition, K use efficiency, economic return and some soil properties, at Batra village, Talkha district, Dakahlia Governorate, Egypt. The treatments used as follows: First experiment: The first factor, two levels of FYM. The second factor, four forms of K sulfate fertilizer powder, granular, tablet and coated tablet. The experimental design was a split plot design with 4 replicates. Second and third experiments: The first factor, four treatments compound between two levels of FYM and two rates of K-foliar application. The second factor, two forms of potassium sulfate fertilizer in second experiment (powder and granular), and four forms in third experiment (powder, granular, tablet and coated tablet). The third factor: five levels of potassium sulfate. The experimental design was a split split plot with 3 replicates. The obtained results could be summarized as follows: 1- First experiment: The liberation of K from the different forms under with or without FYM was as follows: Granular ≥ Powder > tablet > Coated Tablet. 2-Second and third experiments: 2.1- Leaves No./plant, plant height and leaf area were affected by soil application of K-levels in two forms, foliar K application with FYM and their interactions. 2.2-Dry shoot yield, total fresh tubers yield, plant tuber yield, average tuber weight and tubers No./plant were affected by soil application of K-levels in two forms, foliar K application with FYM and their interactions. 2.3-Dry matter %, protein %, specific gravity and starch % were affected by soil application of K-levels in two forms, foliar K application with FYM and their interactions. 2.4-N %, P % and K % in shoot, tubers and its uptake: were affected by soil application of K-levels in two forms, foliar K application with FYM and their interactions. 2.5-Potassium use efficiency was affected by soil application of K-levels in two forms, foliar K application with FYM and their interactions. 2.6-The values of net return and investment factor were increased by soil application of K-levels in two forms, foliar K application with FYM and their interactions. 2.7-Bulk density, total porosity and EC were affected by soil addition of K-levels in different forms, FYM and their interactions. Available, Exchangeable and Water Soluble K were affected by soil application of K-levels in two forms, foliar K application with FYM and their interactions. CONCLUSION: the positive perspective of this study emphasized on the importance of potassium fertilization for potato especially, the controlled release potassium forms. The study could suggest the tablet form at level of 40 kg K/fed (48 kg K2O = 100 kg K2SO4/fed) with 30 m3 FYM/fed with recommended doses of N (180 kg N/fed) and P (75 kg P2O5/fed) to reach optimum yield with maximum profitability.