Efeitos da rochagem e de resíduos organicos sobre aspectos químicos e microbiológicos de um subsolo exposto e sobre o crescimento de Astronium fraxinifolium Schott

摘要

Degraded areas such as the originated from the construction of the Hydroelectric Plant of Ilha Solteira, where the former top soil was removed, present a naturally low regeneration and bare subsoil, with compaction problems, high global density, high resistance to root penetration and lack in organic matter. In order to recover such areas it is of paramount importance to improve general subsoil conditions. The objective of this research was to verify the effects of ground basalt ('rochagem') and application of different organic residues on the chemical and microbiological aspects of a bare subsoil, and on the growth of 'Gon?alo Alves' (Astronium fraxinifolium Schott), a native cerrado plant. The experiment was conducted under greenhouse conditions, with 17 treatments: subsoil of a degraded area with four levels of basalt (0, 2, 4 and 8 t ha-1), combined or not with 8 t ha-1 of three organic residues (water hyacinth, manure and domestic sewage), resulting in 16 treatments, plus an additional control composed of soil of a preserved cerrado vegetation, with four replications per treatment. Chemical and microbiological subsoil analyses were conducted, besides plant height, fresh and dry matter of shoot and root. The results indicated that the treatments with water hyacinth and manure, with or without basalt, provided the best contributions to improve the chemical and microbiological subsoil conditions, while the plants treated with domestic sewage and basalt presented the best growth. The ground basalt application showed positive results.