Integrated crop-livestock and soil physical quality in Brazilian Cerrado / IntegraÃÃo Lavoura-PecuÃria e a Qualidade FÃsica do Solo na RegiÃo do Cerrado

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Soil physics plays a fundamental role in conserving soil and water in agricultural landscapes and is also a key parameter for accessing the sustainability of agropastoral systems. Both pasture history and management can have a significant effect on soil physical attributes, but conclusive research on this subject remains fragmentary. This work aimed to quantitatively investigate how sensitive key traditional soil physical attributes are in different grazing systems and to the inevitably heterogeneity arising from grazing management practices in two occasions, dry and rainy seasons. The field experiment was carried out at Embrapa Cerrados, Planaltina-DF, in two recent renewed pasture areas in 2005. One area was recovered in an indirect way with integrated crop-livestock system (approach ILP). In the other area, Massai grass was established by a conventional soil tillage (âconventional approachâ). In each season, for pre- and post-grazing conditions, herbage was sampled, in three different levels of high and vigor. In close proximity to herbage-sampling station, in each occasion, disturbed and undisturbed soil samples were taken at 0-5 cm, 5-10 cm, and 10-20 cm depths, for the soil physical characterization. The datas were analysed following a complete random design by a factorial arrangement in a split-plot design. The plot was composited by factorial arrangement by pasture history and season and the split-plot by soil depths. In spite of the considerably high instantaneous stocking-rates was verified that during the grazing periods of around 68 days in the dry season (3,45 and 5,67 animal units.ha-1 for the conventional pastoral system and for the ILP system, respectively), and of 28 days in the rainy season (5,78 and 7,07 animal units.ha-1, for the conventional pastoral system and for the ILP system, respectively), eventual detrimental grazing impacts on soil physical parameters were fully recovered. In the dry season, the bulk density (Ds) was higher for the conventional treatment, from pre- to post-grazing conditions. In the same way, total soil pore volume (VTP), macropores (MACRO), micropores (MICRO) and hydraulic conductivity (Ks) showed lower values for the ILP treatment. After grazing, Ds was not affected by conditions grazing (pre- and pos-grazing). Regarding to depth, there was a reduction in the Ds from the 0 â 5 cm depth compared to others layers. For the attributes VTP, MACRO and Ks, confirming the surface layer is the most affected by cattle trampling. The variation of soil moisture affected the VTP and MACRO, that were lower values in the dry season. The average geometric mean diameter (DMG) was differently affected by season and conditions grazing, that showed lower values in the dry season. The variable Ks indicated similar effect to the historic pastures, with higher values for the ILP treatment, compared with the conventional area. The highest values of Ks were observed in the rainy season. Overall, the soil physical conditions, as indicated by indicators attributes, was not affected in a negative way by the cattle trampling during this research.

ASSUNTO(S)

conservacao de solo e agua soil quality physical attributes grazing pastejo atributos fÃsicos qualidade do solo integraÃÃo lavoura-pecuÃria integrated crop-livestock

ACESSO AO ARTIGO

Documentos Relacionados