South-East Asian countries, particularly Indonesia and Malaysia, have over 25 million hectares or 69% of the world’s tropical peatlands. (Asean and Global Environment Centre – GEC). Due to the decreasing arable land areas, pressure is mounting on the low lying peatlands or peat swamp forest that are often cheap. Peat soil have been reclaimed for agriculture for almost half a century, particularly in Malaysia and Indonesia. In the last 10 years, 6 million hectare of Peat Land have been reclaimed for palm oil, pulp wood, illegal logging and agriculture.

Drainage is unavoidable for agriculture development and oil palm cultivation on peat swamp. It affects hydrology regime of peat dome and ecosystem. Drainage lowered water table, peat soil become dry and vulnerable to fire. Peat swamps are like giant sponges that absorb and soak up excessive rain and river water, thus controlling floods during the rainy season and releasing essential water supplies during the dry season. Haphazard development, however, will rob peat forest of this sponge-like feature.

Lesson learned from Sacramento-San Joaquin Delta and the Everglades of Florida (USA), show the degradation of peat swamp. In the Everglades of Florida the arable organic soils have an average subsidence rate, after initial settlement, of 1 inch (3.05 cm) per year. In the organic soils of the Sacramento-San Joaquin Delta of California (USA), average rate of subsidence is reported as slightly over 3 inches (7.6 cm) a year. Since 1900 much of the Everglades has been drained for agriculture and urban development, so that today only 50 percent of the original wetlands remain. Water levels and patterns of water flow are largely controlled by an extensive system of levees and canals. The control system was constructed to achieve multiple objectives of flood control, land drainage, and water supply. More recently, water-management policies have also begun to address issues related to ecosystem restoration. Extensive land subsidence that has been caused by drainage and oxidation of peat soils will greatly complicate ecosystem restoration and also threatens the future of agriculture in the Everglades.

Reclamation of tropical peat swamp for agriculture and oil palm cultivation is also occurred in Kalimantan and Sumatera island. We face with land subsidence, lose the crucial functions: soaking and storing water to mitigate floods and as a water catchment; buffering coastal lands from the intrusion of salty marine water; filtering pollutants which will otherwise degrade lakes, rivers and groundwater; providing critical wildlife habitat. Soil loss and deterioration will continue and will probably accelerate if proper and prompt measures are not taken to de-couple the progress of economic sectors and their pressures on the soil resource through the integration of soil protection measures into sectoral policies. An appropriate design of drainage system in peat swampland is suggested. The drainage system should prevent the possible loss of water during dry season, able to maintain water table to prevent the soil from drying out and to avoid the rupture of channel embankment. (down load pdf)

Find out more about drainage, maintaining water quality, cultivation, managing pasture and fertiliser needs for peat. You can download a copy (in PDF format) of Environment Waikato’s good management practices for Waikato peat farmers. For Peat’s Sake – part one (pdf) ; For Peat’s Sake – part two (pdf)