Basal respiration and stratification ratio in soil cultivated with citrus and treated with organic residues in the state of Sergipe

The use of organic residues in the soil to improve its quality, provide nutrients to plant growth and increase carbon storage is an ancient practice, but little is known about the application of laminar composting in citrus orchards. The objective of this study was to evaluate the microbial activity through microbial respiration, and the different rates stratification of some variables related to this attribute of an Ultisol cultivated with citrus and treated with organic waste in the state of Sergipe. Soil samples were collected in the layers 0-5 cm, 5-10 cm, and 10-15 cm in a citrus orchard (Citrus sinensis, L. Osbeck) under different treatments 1. Layering organic residue (crop wastes placed in layers under the plant canopy) 2. Layering organic residue + NPK (the same as described in iten 1 + NPK); 3. Humus (Humified organic compost applied under the plant canopy); 4. Humus + NPK (the same as described in iten 3 + NPK); 5. Control + NPK (plant canopy was kept free of residues, + NPK application); 6. Control – NPK (plant canopy was kept free of residues, without application of NPK), with three replications. It has been found that the use of the organic residue in the plant canopy increased microbial respiration rate and total organic matter content, as well as an increase in some chemical attributes as pH, P, Ca and Mg in all treatments compared the control. The ratio stratification was effective to evaluate the influence of different management practices between depths demonstrating an improvement in microbial activity by more practical conservation treatments and indicating that the use of Humus, humus + NPK and alternate layering residues + NPK were the most effective in increasing the organic matter content in the soil