Soil Chemical Profiles Developed from Pyrite-containing Sediments under Banjarese Agricultural Practices in South Kalimantan

Abstract

The reclamation of brackish sediments for agriculture involves the danger that pyrite minerals present in the deposits will be oxidized and produce unfavorable conditions for plant growth. Pyrite minerals are oxidized when the swamp is reclaimed by forest cutting, canal excavation and destruction of the peat cover. In South Kalimantan. Banjarese people cultivate rice using a technique adapted to soils that originate from pyrite-containing sediments, especially where non-acidic water for flushing the toxic materials is available. However, the agricultural land in areas with pyrite-containing sediments is a fragile system. Even the productive rice plots are constantly threatened by the sudden collapse of the delicate balance. To understand the effect of the Banjarese rice cultural practice on soil conditions in areas with pyrite-containing sediments, land use and water management practices were observed in the field, and eight auger samples were taken for laboratory analyses. The results show that intensive leaching of the pyrite-containing sediments leads to the development of a specific soil chemical profile comprising an oxidized horizon, an acid-accumulating horizon, and a reduced horizon. This paper presents details of soil development processes and soil management problems.