Pengaruh Penggunaan Lahan terhadap Sifat Fisiko Kimia dan Erodibilitas Tanah pada Berbagai Kemiringan Lereng ( Studi Kasus desa Ciputri Kecamatan Pacet, Cianjur).

Abstract

The increasing number of population has caused increasing pressure over land utilization. This condition has caused more convertion of forest land into agriculture land. This convertion degrades land quality, as showed by the deterioration of soil chemical and physical characteristic and increasing erosion and sedimentation. A research to study the effect of land conversion on soil quality and soil erodibility was conducted in different slope gradient was conducted at Ciputri Village, Pacet Sub-District, Cianjur. To meet the purpose, twenty soil sample were taken from each forest and dry farm on three different slope classes : 3-8 %, 8-15 %, and 15-30 %. The soil sample then analyzed in soil physical laboratory to obtain data of soil physical characteristic. The Soil erodibility index was then calculated using Wischmeier and Smith (1978) formula. This research shows that bulk density of soil in dry farm is higher than that in forest. While forest permeability value is higher than dry farm, except in slope gradient of 8–15 %. The organic material in the forest is higher than that in dryfarm in the all slope. The percentage of very fine sand and dust in dry farm is relatively higher than those in forest, the opposite was percentage of clay. Based on several physical characteristic of soil mentioned before, it is concluded that Soil erodibility in dry farm is higher than the one in the forest. The Soil erodibility of dry farm are 0.34, 0.33 , and 0.21 for slope gradient of 8-15 %, 3-8 %, and 15- 30 % respectively, while the Soil erodibility of forest are 0.32, 0.26, and 0.16 for slope gradient of 3-8 %, 8-15 %, and 15-30 % respectively. The high Soil erodibility found in dry farm shows that dry farm is easier to be degraded by erosion compared to forest. In this case, the factors that are mostly affecting is percentage of very fine sand and dust, percentage of clay, soil organic material, and permeability. Keyword : soil erodibility, Land uses