The objective of this research is a full characterization and evaluation of potassium release from two types of coffee husk (from wet and dry way) from farms of high and low yield. This experiment will be carried out in columns with soil in a greenhouse at the Faculty of Agricultural Sciences Botucatu (SP). Will be used the surface layer (0-20 cm) of an Oxisol of medium texture (Embrapa, 1999). Will be evaluated two types of materials, coffee husk, from dry way and coffee husk from wet way, both from two different farms, one of high yield and another of low yield. The experiment will be to implement the equivalent of 2.5, 5, 10 and 20 t ha-1, with a control and treatment with application of potassium fertilizer mineral in an amount equal to the dose of 10 t ha-1 straw approximately 300 kg ha-1 of K20. The experiment will be conducted for a period of 10 months and at the end of the test will be collected soil samples and analyzed the content of K in different depths.There will be a full characterization of different types of coffee before the application used in the experiment and after the end of it. For the characterization will be used the analysis of potassium, total carbon, lignin, cellulose, hemicellulose and dry. In addition to the test will be made of nylon bags to assess the changes of four types of coffee husk using the litter bag method. Will be collected 7 samples of coffee husk from the bags it will be on 15, 30, 45, 90, 150, 210 and 300 days from the beginning. Samples will be analyzed using the same methodology of the analysis initial and final coffee husk. The experiment is a factorial block design with four replications. Will be conducted regression analysis and adjusting will be significant until equations 5% probability by F test.
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