Resumo

GONZALEZ MOLINA, Lucila et al. Performance of the Rothc-26.3 model at the plot level in Mexico. Terra Latinoam [online]. 2016, vol.34, n.3, pp.357-366. ISSN 2395-8030.

To comply with the guidelines of the Intergovernment Panel on Climate Change (IPCC), it is necessary to report changes in soil organic carbon (SOC) stocks. The RothC-26.3 (RothC) model is one of the most used models worldwide to study C dynamics in different systems. This study evaluated the performance of RothC in simulating SOC stocks changes at the plot level in short-term experiments. Nine sites were assessed as well as five systems: agriculture with plant residues (A+R), agriculture without residues (A-R), forest (F), grassland (GL) and grazing commons (GRC). The experimental plots were located in the states of México, Tlaxcala, Michoacán, Guanajuato, Oaxaca, Jalisco and Nuevo León. RothC was run (i) with SOCinitial measured at each sampling point (*CIPUN) only in the plot in the Sierra Norte of Oaxaca and (ii) with average SOCinitial measured in each plot (*CIPAR) in the rest of the plots. The entry parameters of the model, as well as the plant residues and organic fertilizers, were measured and estimated. The degree of association r between measured and simulated SOC was in the range of 0.7 to 1.0 in all of the sites. Model efficiency (EF) was between 0.53 and 0.93, except at the Batán site where tillage systems were assessed. In the evaluation by system, in both forms of simulation, r was between 0.63 and 0.95, except in GRC. EF was 0.48 to 0.84 in A+R and A-R and 0.81 in F *CIPAR. The grazing commons are complex because of heterogeneity of vegetation, soil, climate variability and grazing. Considering the results in the study sites, RothC can be used acceptably in the simulation of SOC changes without modifying its internal parameters.

Palavras-chave : plant residues; land use; cropping systems.

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