|Olk, Daniel - Dan|
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 11/15/2004
Publication Date: 1/28/2008
Citation: Olk, D.C., Becker, M., Linquist, B.A., Pandey, S., Witt, C. 2008. Integrated Nutrient Management: Experience from rice-based systems in Southeast Asia. In: Aulakh, M.S. and Grant, C.A., editors. Integrated Nutrient Management for Sustainable Crop Production. Haworth Press/Taylor & Francis. New York, NY. p. 369-420.
Technical Abstract: Integrated nutrient management combines the use of mineral and organic fertilizers. In the rice-based rotations of Southeast Asia, organic fertilizers, especially green manures, were once widely used, but in recent years they have been increasingly replaced by mineral fertilizers. In this region organic fertilizers have clearly improved soil properties and crop growth in sandy, low-carbon soils planted to rainfed rice in Northeast Thailand, but the economic benefit is less certain. Yields in such unfavorable environments have been maximized through simultaneous use of both organic and inorganic fertilizers. Green manuring is known to increase nitrogen availability and grain yield of rainfed rice, but its benefits to other soil properties are largely ignored during agrosystem evaluation. Irrigated lowland rice systems of Southeast Asia are more input-intensive and higher-yielding than rainfed systems, so an increasingly appropriate form of organic fertilizer is rice straw. It provides comparable benefits to soil properties and nutrient cycling as do other organic fertilizers without requiring cultivation of additional crops. A recent form of integrated nutrient management is the basing of inorganic fertilizer rates on native soil fertility. This approach has increased yields and optimized fertilizer inputs for lowland rice fields, but it has not yet been widely implemented in rainfed rice areas of Southeast Asia. An agricultural economy typically evolves through four stages that are defined by population density and income level. Most of Southeast Asia has evolved beyond the second stage, during which organic fertilizers are most profitable. As the region continues to develop, future use of organic fertilizers will likely be driven by environmental concerns.