Impact of forest–pasture conversion on soil physical and chemical properties

The objective of this paper is to assess the changes in soil physical and chemical properties resulting from conversion native forest pasture secondary state Santa Catarina, Brazil. Seven forest–pasture successional stages were identified using aerial photographs satellite images acquired 1957, 1978, 2008. Successional coded as FFF, FPF, PFF, PPF, FPP, FFP, PPP, where first, second, third letters refer land uses (P, pasture; F, forest) practiced 2008, respectively. Soil samples collected by layer at depths 0–10, 10–20, 20–40, 40–60, 60–80, 80–100 cm. Clay contents, bulk density (Db), macroporosity (MP), microporosity (mP), pH, Aluminum (Al), cation exchange capacity (CEC), calcium (Ca), potassium (K), phosphorus (P), total organic carbon (TOC) content, stock, δ13C abundance quantified. Conversion increased P, K, Ca, Db, mP; reduced MP, TOC stocks. largest stocks occurred sites occupied forests but previously used pastures. Forest age influenced values, different isotopic signatures for sites, confirming transition C3 C4 plants. In 50-year-old pastures, about 66 % still derived primary biomass.