SciELO - Scientific Electronic Library Online

 
vol.36 issue3Least limiting water range and degree of soil compaction of an oxisol after 30 years of no-tillageSoil resistance to penetration and forage and root production at different grazing intensities author indexsubject indexarticles search
Home Pagealphabetic serial listing  

Revista Brasileira de Ciência do Solo

Print version ISSN 0100-0683

Abstract

DA-SILVA, Vagner Lopes et al. Improvement of an oxisol structure by no-till cropping systems in the region of Campos Gerais, Paraná. Rev. Bras. Ciênc. Solo [online]. 2012, vol.36, n.3, pp. 983-992. ISSN 0100-0683.  http://dx.doi.org/10.1590/S0100-06832012000300028.

The quality of no-tillage systems depends on an adequate soil management that promotes soil structure improvements. This is associated to the cropping system adopted. This study investigated the effect of long-term no-tillage systems (18 years) on the structural quality of a sandy-clay to clay Oxisol (Latossolo Vermelho) in the region of Campos Gerais, Paraná, Brazil. Five cropping systems were assessed: wheat-soybean [Wt-So], black oat-maize-wheat-soybean [Ot-Mz-Wt-So], vetch-maize-wheat-soybean [Vt-Mz-Wt-So], ryegrass-maize-ryegrass-soybean [Rg-Mz-Rg-So]; and alfalfa-maize [Alf-Mz]. Soil was sampled from the layers 0-5, 5-10 and 10-20 cm, in cylinders and in blocks with undisturbed structure. In the 0-5 cm layer, bulk density was lowest in the Ot-Mz-Wt-So (0.96 Mg m-3) and Vt-Mz-Wt-So systems (0.93 Mg m-3). In the 5-10 and 10-20 cm layers, the bulk density tended to be lowest in Alf-Mz systems (1.14 and 1.17 Mg m-3, respectively). A similar trend was observed for macroporosity, which in the top layer was greater in Ot-Mz-Wt-So (0.29 m3 m-3) and Vt-Mz-Wt-So (0.30 m3 m-3) and in the 5-10 and 10-20 cm layers tended to be greater in the Alf-Mz system (0.19 m3 m-3). No clear trend was observed for microporosity. The saturated hydraulic conductivity was directly related with macroporosity, and was highest for Vt-Mz-Wt-So in the 0-5 cm layer (224 mm h-1) and Alf-Mz in the layers 5-10 (170 mm h-1) and 10-20 cm (147 mm h-1). In the Vt-Mz-Wt-So system, the mean weight diameter of aggregates was lowest in the 0-5 cm layer (2.39 mm) and highest (3.04 mm) in the Wt-So. The highest cone index values were observed in the Wt-So system, with over 1.5 MPa in the 7.5-22.5 cm layer. The compaction degree was lowest in the Alf-Mz system (0.2 MPa cm). Results were attributed mainly to the role of the crop roots of the systems and to the intensity of machinery traffic. Considering the 0-20 cm layer as a whole, the capacity to promote soil structural quality improvements was greater for the semi-perennial Alf-Mz system than for systems based on annual species. Bi-annual rotation systems, based on cover crops such as black oat and vetch, promote soil structural quality improvements compared to the wheat - soybean succession.

Keywords : Crop rotation; legumes; cone index; soil aggregation; density; porosity.

        · abstract in Portuguese     · text in Portuguese     · pdf in Portuguese