Soils of the tropical forests of Leyte, Philippines II: Impact of different land uses on status of organic matter and nutrient availability

In order to verify the hypothesis that conversion of forest to agriculture and other secondary land uses does not necessarily cause OM and nutrient depletion in the soil, we conducted this research at two locations, one an Andosol (Andisol) area and the other an Alisol (Ultisol) in Leyte, Philippines. In each location, adjacent sites having different land uses but with the same soil type, physiography and geology, were chosen as sampling sites. These included: forest, grassland, pasture and bushland for the Andosol in Ormoc, and forest, reforestation, coconut + bushes, shifting cultivation and coconut + kudzu, for the Alisol in Baybay. Our results indicate that a change in land use or cultivation decreased the soil OM, total and available N, available K but tended to increase pH and available Ca and Mg. Available P, which was very low in both soils, showed no distinct differences measurable. The soil changes in the Andosol were greater and more distinct than in the Alisol. Land use history helps explain soil changes due to land use.