Alterações em atributos microbiológicos de um solo de tabuleiros costeiros cultivado com mamão, sob diferentes manejos de cobertura vegetal

Abstract

The cultivation of the papaya tree in the soils of Coastal Boards needs differentiated handling, seeking to decrease limitations due to the existence of layer coesa, low text of nutrients, increase of the acidity in depth and it lowers capacity of retention of water. Alterations were evaluated in some attributes microbial of a soil of Coastal Boards, under different handlings of vegetable covering, in the culture of the papaya, in different times and depths being objectified to quantify the quality of the soil. Samples were collected in a field experiment with four years of cultivation, composed by nine treatments in delineamento of blocks casualizados with three repetitions, being selected six treatments for evaluation: 1 - it weeds in total area; 2 - harrwing in between rows; 3 - Crossed sub soiling before planting the crop + bean-of- pig (Canavalia ensiformis) in between the rows; 4 - Crossed sub soiling before planting the crop + cowpea (Vignia sp.) in between the rows; 5 - Crossed sub soiling before planting the crop + lime + gypsum and bean-of-pig in the between the rows; 6 - Crossed sub soiling before planting the crop + nativevegetation, the area was cleared when necessary. The soil samples and rootses were collected in May (beginning of the rains) and November (beginning of the dry period) of 2002, in the depths of 0 – 10 and 10 - 30cm, in the streets of the culture. It was proceeded the following analyses microbial and biochemistries: carbon of the microbial biomassa, soil respiration, enzyme activity (reduction of Fluoresceín Diacetate - FDA and acid phosphatase), population of bacterias and fungi, population of amonifiers and nitrifiers, number of spores of fungi micorrízicos arbusculares and colonization micorrízica in the papaya rootses. It is ended that: a) the handlings employees influenced the basal breathing, the population of microrganisms nitrifiers oxidizers of the nitrito, the activity of acid phosphatase and the number of spores of mushrooms micorrízicos; b) the maintenance of a vegetable covering is important for the activity of the microorganisms of the soil, however, this effect was differentiated with the type of vegetable covering; c) the sub soiling didn't cause alterations in the characteristic microbiologys in depth; d) the biomass accumulation and microbial activity decreased with the depth of the soil; e) the legumes pig bean stimulates the presence of bacterias nitrifiers, that is to say, the nitrifiction process; f) the density of spores of mushrooms micorrízicos was altered by the sampling depth; g) the evaluations microbiologys comes sensitive to different handling systems and vegetable covering.