Bioavailability of Silica on Paddy Soils with Various Land Aging in Musi Rawas South Sumatera of Indonesia

Abstract

Utilization of intensive paddy soils for rice cultivation are main causing deficiency of soil silica (Si) due to high concentration Si adsorption in soils with values varies between 230 up to 470 kg ha -1 . The soil silica availability on agriculture lands in Indonesia varies from 203 to 982 mg kg -1 , and the paddy soils in Java and Sumatra have shown a decreasing the silica between 11% to 20% in the last three decades, resulting in declining paddy soils productivity. This study was aimed to investigate the availability of silica in the paddy soils distributed in Musi Rawas. The study was scheduled from May to November 2016 using survey methods, and soil analyzes performed in laboratory of SEAMEO Biotrop Bogor.The results showed that availability of silica in wetland has reduced by 50% in two decades, and meanwhile the availability of silica in irrigated soils about 7.5 times lower compared to rainfed soils. The silica availability of irrigated soils from wetland had 4.5 times higher than the irrigated soils of dryland. Furthermore, silica contained in rice husk had also decreased down to 74.5%, resulting in the decreasing of grain production due to a decrease in availability of silica in soil.