Title: Soil Organic Carbon Thresholds and Nitrogen Management in Tropical Agroecosystems: Concepts and Prospects
Authors: MUSINGUZI PatrickTENYWA John StephenEBANYAT PeterTENYWA Moses MakoomaMUBIRU Drake NBASAMBA Twaha AliLEIP Adrian
Citation: Journal of Sustainable Development vol. 6 no. 12 p. 31-43
Publisher: Canadian Center of Science and Education
Publication Year: 2013
JRC N°: JRC85704
ISSN: 1913-9063
URI: http://www.ccsenet.org/journal/index.php/jsd/article/view/29014
http://publications.jrc.ec.europa.eu/repository/handle/JRC85704
DOI: 10.5539/jsd.v6n12p31
Type: Articles in periodicals and books
Abstract: Soil organic carbon (SOC) is a potential soil fertility indicator for regulating nitrogen application in tropical farming systems. However, there are limited studies that have discussed SOC thresholds above or below which crop production could be diminished, or at which no or high response to nitrogen (N) application can be realized. This review explores the drivers of SOC concentration relevant for the establishment of thresholds. We further evaluate existing SOC thresholds for provoking no yield response or significant response to added N fertilizer. Key drivers for SOC concentration relevant in establishing thresholds are mainly climate, topography, texture, and land use management. Soil organic carbon threshold for sustaining soil quality is widely suggested to be about 2% below which deterioration may occur. For added N fertilizer management, specific SOC thresholds seem quite complex and are only valid after assuming other factors are non-limiting. In some soils, SOC levels as low as 0.5% result in fertilizer responses and soils as high as 2% SOC also respond to small N doses. Minimum SOC thresholds can be identified for a given soil type, but maximum thresholds depend on crop N requirements, crop N use efficiency and amount of N applied. However, there seem to exist critical total SOC ranges that could be targeted for optimal indigenous N supply and integrative soil functional benefits. These can be targeted as minimum levels in soil fertility restoration. In all, it is still difficult to establish a single minimum or maximum SOC threshold value that can beuniversally or regionally accepted.
JRC Directorate:Sustainable Resources

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