Resumo

CANTU SILVA, Israel  e  YANEZ DIAZ, María Inés. Effect of the change of land use on the contents of soil organic carbon and nitrogen. Rev. mex. de cienc. forestales [online]. 2018, vol.9, n.45, pp.122-151. ISSN 2007-1132.  https://doi.org/10.29298/rmcf.v9i45.138.

Soils are the largest carbon reservoir, containing almost three times as much as aerial biomass. Changes in land use represent the second anthropogenic source of carbon into the atmosphere due to carbon emissions. Carbon and nitrogen content in four contrasting land-use systems were evaluated, Tamaulipan thornscrub, agricultural crop, grassland and eucalyptus plantation. Four soil samples at two depths were collected per site (0-5 and 5-30 cm) and the soil organic carbon content (COS), total nitrogen (Nt) were analyzed and the C/N ratio was estimated. The results for the COS and Nt content for the 0-5 cm depth were 1.4-0.16 % (agricultural), 2.4-0.27 % (plantation), 3.41-0.33 % (pasture) and 4.1-0.43 % (Thornscrub land), respectively. Overall the contents of COS and Nt at depth 5-30 cm. decreased. The C/N ratio showed values between 8.7 and 10.4 at both depths, indicating effective humification and mineralization of organic matter. COS and Nt losses due to changes in the use of Thornscrub land to another land use system fluctuated between 2.4 % to 66 %, the COS decreased mainly at soil depth 0-5 cm, while Nt value decreased most at soil depth of 5-30 cm. The agricultural system experienced the greatest loss of COS and Nt, at both depths. The results indicated that changes in land use caused a decrease in soil fertility, which was reflected in the agricultural system, where the values of C and Nt were lower than those found with the Thornscrub vegetation.

Palavras-chave : Soil organic carbon; fertility; Tamaulipan thornscrub; nitrogen; land use system; Vertisol.