Densidade de microrganismos do solo sob diferentes sistemas de uso no perímetro irrigado várzeas de Sousa – Paraíba.

Abstract

Agro-industrial activities in arid and semiarid regions, while fighting the limiting of production, may alter the soil characteristics. Due to high sensitivity to anthropogenic activity, the biological attributes have great potential as indicators of soil quality, among which stands out the density of microorganisms. Given this, we aimed to evaluate the density of soil microorganisms under different land use systems in the Irrigated Várzeas de Sousa - PB. To meet this purpose, soil samples of systems occupied by plantations of coconut, banana and coconut, fallow were collected and soil samples in the area of preserved environment , which is used as reference. The density was measured by the technique of the most probable number (MPN) using specific to bacteria, fungi, actinomycetes, phosphate solubilizing soil and diazotroph culture media. Was no occurrence of bacteria, fungi, actinomycetes and phosphate solubilizing in all soil samples of different land use systems studied. There was occurring in the media NFB diazotroph JNFb and inoculated with soil suspensions of all soil samples of the use of the studied soil systems. There was no difference between the depths 0-15 cm and 15-30 cm of the studied areas. Soil samples from the legal reserve area of Caatinga showed the lowest densities of microorganisms, whereas the soil samples of systems with only greens and fallow had the highest density of bacteria. The soil of the fallow system showed higher density of total fungi. In systems with higher density coconut phosphate solubilizing and diazotroph grown on the medium were NFB. There was no difference between the systems use for density of actinomycetes and diazotroph who grew up in the middle JNFb.