The chapter reports on empirical results from study sites on the island of Sumatra, Indonesia. The area was chosen to represent the lowland humid tropical forest zone in Asia for the global Alternatives to Slash and Burn project (ASB). The 'ASB matrix' of indicators is applied to a series of crop monoculture, agroforestry and forest management land uses in Sumatra. The ASB research in Indonesia is distinguished by including analysis of large estates as well as smallholder activities. At least six distinct interest groups have a stake in the trajectory of land-use in Sumatra, but there are crucial differences among them in the weights they place on the various economic and environmental outcomes of forest conversion.
Nitrification‐denitrification is often regarded as an important N loss process in puddled rice soils, but few direct field measurements of denitrification loss have been reported. Field studies were conducted on a Typic Tropaquept in Thailand, an Aeric Tropaqualf in Indonesia, and an Andaqueptic Haplaquoll in the Philippines to measure (N2 + N2O)‐15N flux, (N2 + N2O)‐15N trapped in soil, and total gaseous 15N loss following basal application of 15N‐labeled urea (87 kg N ha−1) to irrigated rice (Oryza sativa L.) grown on puddled soils. Urea treatments included broadcast applications with and without incorporation to 0.07‐m soil depth. Directly measured (N2 + N2O)‐15N flux during the 10 d following urea application by each method was less than 0.1% of the applied N at the Thailand and Indonesia sites. The (N2 + N2O)‐15N collected from the soil after 10 d did not exceed 0.02% of the applied N. Total gaseous N loss determined from a 15N balance at 10 d after N application without incorporation was 34% of the applied N in Thailand and 31% in Indonesia. Incorporation reduced total N loss to 22% in Thailand and 10% in Indonesia. In the Philippines, the measured (N2 + N2O)‐15N flux during the 15 d immediately following urea application with incorporation was 2.2% of the applied N with chambers placed between rice plants and 3.0% with chambers over the plants. Total N loss at the Philippine site was 40% of the applied N. Ammonia volatilization appeared to be much more important than nitrification‐denitrification as a mechanism of urea‐N loss at the three irrigated lowland study sites.
Geographical position of Indonesia that lies between Asia and Australia continents and between Indian and Pacific Oceans has both advantages and disadvantages. Monsoon climate offers opportunity for food crop intensification. The geographical position also protects Indonesia from heavy and continuous destruction of agriculture caused by cyclone or typhoon. However, high rainfall hitting the soil surface susceptible to erosion on sloping topography cause serious erosion and sedimentation of rivers and reservoirs. The negative impacts of extreme weather due to the global climate change are aggravated by serious degradation of the watershed. Uncontrollable growth of the population and conversion of productive agricultural land lead to expanded degradation of watersheds and shrinkage of agricultural lands causing imbalanced proportion of supply and demand for food. It is estimated, that the dependence of Indonesia on imported rice will be lasting until 2025. Volume of imported rice will be the lowest when high rate of production increase scenario is implemented, though this approach requires a high budget. National Rice Production Enhancement Program (P2BN) is launched to increase rice production. ICM (Integrated Crop Management) technology is implemented in P2BN and has pushed rice production up to self-sufficiency level in 2009. SRI (System of Rice Intensification) technology is also offered, but its adoption is limited because of inadequate supply of organic fertilizers and bio-pesticides as well. Supply chains of raw materials of organic fertilizers and bio pesticides are neglected by SRI promoting parties. All parties need to follow eco-anthropological approach in order to compromise agricultural intensification programs with environmental protection. Because of limited areas of irrigated land, ICM technology with some modifications has to be expanded to rainfed, swampy and tidal swamp and dry land areas. Holistic and comprehensive strategy should be explored to convert conditions from the vicious circle to the virtuous one for food crop production in the coming years.
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