An evaluation of the century model to predict soil

Authors: Maren Oelbermann R P Voroney

Publish Date: 2010/10/13

Volume: 82, Issue: 1, Pages: 37-50

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Abstract

Greater organic matter inputs in agroforestry systems contribute to the longterm storage of carbon C in the soil and the use of simulation models provides an opportunity to evaluate the dynamics of the longterm trends of soil organic carbon SOC stocks in these systems The objective of this study was to apply the Century model to evaluate the longterm effect of agroforestry alley crop and sole crop land management practices on SOC stocks and soil C fractions This study also evaluated the accuracy between measured field data obtained from a 19year old tropical TROP and 13year old temperate TMPRT alley crop and their respective sole cropping systems and simulated values of SOC Results showed that upon initiation of the TROP and TMPRT alley cropping systems levels of SOC increased steadily over a ~100 year period However the sole cropping systems in both tropical and temperate biomes showed a decline in SOC The active and passive C fractions increased in the TROP agroforestry system however in the TMPRT agroforestry system the active and slow fractions increased The input of organic matter in the TROP and TMPRT agroforestry systems were 83 and 34 greater respectively compared to the sole crops which likely contributed to the increased SOC stock and the C fractions in the alley crops over the 100 year period Century accurately evaluated levels of SOC in the TROP r 2 = 094 RMSE = 226 g m−2 and TMPRT r 2 = 094 RMSE = 261 g m−2 alley crops and in the TROP r 2 = 082 RMSE = 101 g m−2 and TMPRT r 2 = 083 RMSE = 64 g m−2 sole crops Century underestimated simulated values in the alley cropping systems compared to measured values due to the inability of the model to account for changes in soil bulk density with increasing organic matter inputs with tree age from prunings or litterfall

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