Abstract

CRUZ RUIZ, A. et al. Microbial biomass in mountain soils with different uses: a laboratory study. Terra Latinoam [online]. 2012, vol.30, n.3, pp.221-228. ISSN 2395-8030.

The agricultural use of soil of Parque Nacional Nevado de Toluca (PNTT), involves farming practices such as the growing use of agrochemicals. To investigate the influence of widespread application of nitrogen fertilizers and biocides in the area, a study was conducted on microbial biomass and mineralization of carbon (C). PNNT soils used for different purposes were incubated: forest soil under oyamel (Abies religiosa) canopy (forest), soil under grassland for grazing livestock (grassland) or soil cultivated under maize (cultivated). The soils were amended with ammonium sulfate (585.36 kg ha-1) (ammonium treatment), urea (250 kg ha-1) (urea treatment), 2, 4-D (1 L ha-1) (2, 4-D treatment), captan (2 kg ha-1) (captan treatment) and soil with no amendment. Mineralization of C, nitrogen microbial biomass (NMB) and carbon microbial biomass (CMB) were measured after 56 days of incubation. The results showed that forest to agricultural land use change reduces the proportion of CMB, and NMB in agricultural soils was 55% lower than in forest soils. The 2, 4-D and captan treatments significantly decreased CMB in forest soils; it was almost 40% less than that in soil without amendment. Captan treatment increased CMB in grassland and cultivated soils. The urea treatment increased NMB in three soils with different use. Addition of sulfate of ammonium, urea, 2, 4-D amine or captan caused differentiated effects on soils of forest, grassland and cultivation, indicating that the impact of the biocides and fertilizers is related to degradation.

Keywords : land use change; nitrogen fertilizers; biocides.

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