Physical degradation of a Red Latosol used for intensive forage production

The intensive traffic of agricultural machines on soils used for hay production can result in soil quality degradation. The hypothesis evaluated was that systems of intensive hay production cause soil physical degradation. The objective of this study was to quantify the soil physical properties and morphological attributes to recognize and identify the soil physical degradation of a Red Latosol (Typic Haplorthox) cropped with Tifton 85 forage (Cynodon spp) for hay production, in western Parana state, southern Brazil. A native forest area adjacent the experimental area was used as reference for soil physical quality. Morphological attributes were described in both soils and, in the A and Bw horizons, the following soil physical properties were measured: bulk density, porosity and pore size distribution, and soil resistance to penetration (SRP). The analysis of these variables confirmed the hypothesis. Soil morphological description showed the occurrence of soil. compaction as well as drastic alterations in macromorphological characteristics at a depth of 0.15 m in the soil under forage cultivation for hay production. Reductions in soil total porosity and macroporosity were verified as well as increases in soil bulk density and SRP. Under intensive forage production the air-filled porosity in the soil surface layer was found to be lower than 10% and SRP over 2.5 MPa. The morphological attributes only allowed identifying where soil physical modifications occurred, while the soil physical properties indicated the degree of the soil physical degradation. The SRP curve clearly demonstrated the soil physical degradation in the surface layer of the soil used for cultivated with forage for hay production.