Soil Organic Carbon Thresholds and Nitrogen Management in Tropical Agroecosystems: Concepts and Prospects
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Date
2013
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concepts and prospects.
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 be universally or regionally accepted
Description
Keywords
critical level, soil organic carbon fractions, tropical soils, efficiency, yield
Citation
Musinguzi, P., Tenywa, J. S., Ebanyat, P., Tenywa, M. M., Mubiru, D. N., Basamba, T. A., & Leip, A. (2013). Soil organic carbon thresholds and nitrogen management in tropical agroecosystems: concepts and prospects.