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Modelling soil organic matter decomposition and rainfall erosion in two tropical soils after forest clearing for permanent agriculture
Author(s) -
Bouwman A. F.
Publication year - 1989
Publication title -
land degradation and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.403
H-Index - 81
eISSN - 1099-145X
pISSN - 1085-3278
DOI - 10.1002/ldr.3400010205
Subject(s) - environmental science , soil water , organic matter , erosion , soil organic matter , soil carbon , tropics , soil science , temperate climate , total organic carbon , soil retrogression and degradation , hydrology (agriculture) , ecology , geology , biology , paleontology , geotechnical engineering
A soil organic matter turnover model has been developed to analyse soil carbon (soil organic‐C) loss caused by organic matter decomposition and rainfall erosion in soils used for permanent cultivation. It has been used to build up model profiles of five soils, one occurring in temperate and four in tropical regions, on the basis of estimates for ‘natural’ organic matter input. Organic matter input data for different systems of cultivation were used to model the long‐term decomposition of soil organic‐C in these model profiles. The modelling results show that soil organic matter decomposition in the tropics is three to four times faster than in temperate regions, and that there is a marked influence of soil type and soil climate. Simulated losses of organic‐C in the tropical soils, not accounting for erosion are 31 to 50 per cent after 50 years and 43 to 63 per cent after 100 years of continuous cultivation. The simulated loss of soil organic‐C when rainfall erosion is also allowed for is 40 to 80 per cent. Erosion caused an extra loss of at least 7 per cent after 100 years. The initial input of charcoal from forest burning is lost through erosion at a rate of 50 to almost 100 per cent, depending on the severity of erosion. The sensitivity of modelling results to variations in input data was also analysed. The losses of soil carbon were also used to calculate the global flux of CO 2 from soils. Soils are probably a small but not negligible source of CO 2 .