Soil compaction has been a very common problem on the fields, affecting growth and yield of the crops as well as soil and water conservation. In order to study this problem, five winter green manure species (Vicia sativa; Raphanus sativus; Lupinus albus; Avena strigosa and Avena sativa) were cultivated in four soil profiles with increasing levels of subsurface compaction (soil bulk densities: 1.31, 1.43, 1.58 and 1.70 Mg m-3). The experiment was carried out in pots under greenhouse conditions at FCA/UNESP in Botucatu, São Paulo in 1998, using a sandy loam Dark Red Latosol (Acrudox). As soil compaction increased, root length and dry matter increased above the compacted layer decreasing below it, concentrating the root system of the plants close to the surface. Root mean diameter of L. albus, A. strigosa and A. sativa increased in the compacted layer with increasing soil density, decreased for V. sativa and was not altered for R. sativus. Raphanus sativus and A. strigosa showed the best performances on root growth, with higher values of root length density in both compacted and inferior soil layers, and in the pot as a whole, even with increasing soil compaction. This study shows that R. sativus and A. strigosa came out as good materials for ameliorating the characteristics of soils with subsurface compaction, showing vigorous root growth inside and below the compacted laye. These results, however, should be validated in the field, under different soil and climate conditions.
compacted layer; cover crops; root