Abstract
The use of mathematical models is an alternative way to understand how management practices affect soil organic matter (SOM) dynamics because such models yield results on time scales that would be impossible to observe in field studies. The aim of this study was to parameterise and calibrate the application Century 4.0 in terms of the edaphoclimatic conditions of a Latossolo Vermelho-Amarelo of the Araripe Plateau and simulate the soil C dynamics in each compartment. The study was conducted in the Araripe National Forest (Floresta Nacional do Araripe ― FLONA). The soils are classified as Latossolos Vermelho-Amarelos with a medium clayey texture and a clay fraction consisting of kaolinite with iron and aluminium oxides. The physical and chemical properties of the soils were obtained at a depth of 0.00-0.20 m in 2012 and 2013. The best total organic carbon (TOC) result was an error of only 3% between the measured and simulated values, which was obtained with a PRDX (4) adjustment of 140 g m-2 C. After correcting for the C decay rate in the passive (PC), slow (SC) and active compartments (AC), absolute errors lower than 10% were obtained for the C values. The abiotic correction factors specific to each compartment were 0.89 for the active and passive compartments and 1.12 for the slow compartment. The sensitivity analysis indicates that all compartments are sensitive to variations in maximum and minimum temperature and that the clay content affects the TOC and the passive compartment. Key words: Century model calibration, soil carbon compartments.
Highlights
Stocks of soil organic matter (SOM) are sensitive to cultivation practices, land-use conversions, mineralogy and edaphoclimatic conditions of a region, all of which affect its long-term balance and decomposition (Lin et al., 2014)
The underestimation of the total organic carbon (TOC) in the passive compartment is consistent with the results obtained by Silva and Mendonça (2007)
The underestimation in the passive compartment in tropical soils dominated by kaolinite arises from the interference of the Fe and Al contents in the stabilisation of SOM
Summary
Stocks of soil organic matter (SOM) are sensitive to cultivation practices, land-use conversions, mineralogy and edaphoclimatic conditions of a region, all of which affect its long-term balance and decomposition (Lin et al., 2014). Soils with a high degree of weathering such as the Latosols (predominance of low-activity clays) are very dependent on organic matter to maintain adequate function and sustainability (Silva and Mendonça, 2007). The use of mathematical models is an alternative approach to understanding how management practices affect the SOM dynamics in that such models yield results on time scales that would be impossible to observe in field studies. Several mathematical models have been developed to address the SOM distribution in compartments with various soil decay and permanence rates, that is, active (rapid cycling), slow (intermediate) and passive (slow) rates. The proposed model is used to classify the SOM into compartments of decreasing rates that follow first-order kinetics
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