Atividade microbiana em solo de Tabuleiros Costeiros da Bahia na cultura da laranja "pêra"

Abstract

The citrus orchards are concentrated in the Littoral area of the Northeastern region of Brazil, with the predominance of Table Land yellow dystrophic cohesive Latosols. These soils present several limiting factors for crop productivity, such as, low nutrient levels, (low levels of organic matter, associated to low levels of the total bases, CTC, and low phosphorous levels), low water retention capacity and physical impediment to root growth. The soil microbial diversity has a direct relationship with the organic matter dynamics. The soil management practices have a significant affect in the soil microbial biomass and activity, which tend to respond more rapidly to soil disturbances due to agricultural practices than other soil characteristics such as levels of organic matter, which can take several years to show significant alterations. Therefore, the microbial biomass, as an indicator to evaluate the alterations in the soil biological properties, becomes an important component in studying the sustainability of an agricultural system. This study had the objective of evaluating the impact of different soil management practices with green manure ground cover in the microbial activity of the cohesive Table Land soil of the State of Bahia. The results showed that the different management systems had no effect on the soil microbial carbon (C- BMS), independently of the sampling period and site (planting rows and between planting rows). The highest values of soil microbial respiration and the highest metabolic quotient were obtained in the dry and high temperature season, for the soil between the citrus planting rows. For the soil chemical characteristics, the microbial biomass carbon and soil respiration, the two year period of soil management and ground cover is a very short period to evaluate the impact of theses systems in relation to the conventional local farmers system. For the fluorescein diacetate hydrolyses (FDA), as a measure of total microbial activity in the soil, the results obtained indicate that the enzyme activity is affected by the climatic seasonal variations, being the highest enzyme activity in the month of April.