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- Release of Potassium and Magnesium from Some Philippine Soils
Release of Potassium and Magnesium from Some Philippine Soils
Thesis Abstract:
A greenhouse experiment was conducted primarily to assess the supplying capacity of K and Mg of five soils from different sugarcane plantations and to determine the effect of K and Mg fertilizers on the growth and dry matter yield of guinea grass when applied singly or in combination.
Results indicated that the dry matter and K yields of the test plants increased with increase in the level of K applied either singly or in combination with Mg. Applied Mg had no influence on dry matter, K and Mg yields, but it showed an antagonistic effect on K.
Based on the total K uptake and dry-matter production and according to their K-supplying capacity, the soils could be rated in descending order as follows: Carmona clay loam. Also, according to Mg-yielding ability, the ranking order is as follows: Carmona, San Fabian, Ibaan, Guadalupe and La Paz.
In the control treatments, Guadalupe, La Paz and San Fabian soils released non-exchangeable K, but Carmona and Ibaan soils fixed exchangeable K. With K application, there was a release of K from Carmona, La Paz and Guadalupe soils, while K fixation was found on San Fabian and Ibaan soils. All soils showed no release of non-exchangeable Mg under all treatments owing to the abundance Mg.
Soil available K extracted through three chemical methods was found highly related to the total K uptake by guinea grass. However, positive but low correlation was observed between the chemically extracted soil Mg and total Mg uptake by the plants. Results suggest the use of other chemical methods for satisfactory assessment of the mg-supplying capacity of Philippine soils.