Avaliação da respiração basal do solo de um agroecossistema urbano biodiverso

Abstract

Agroecosystems are characterized by the sustainable management of inputs for food production, generating resources that are used or transformed by the system's own capacity for energy direction and distribution of each working material. The diversity of plant species present in the system contributes to the expansion of functions performed by each of them and, consequently, their applicability. For assessing soil health and microbial activity, biological analyses present themselves as important quantitative and qualitative methods, such as Basal Soil Respirometry (BSR) using the titrimetry method. The method evaluates the oxidation of soil organic matter by soil microbiota and quantifies the production of C-CO2 per unit of mass of soil over a given period. In this context, a respirometric evaluation was carried out on the soil of a biodiverse urban agroecosystem in Fortaleza/CE, where composite samples were collected from four treatments representative of sectors of the system for comparative purposes of microbiological activity. The treatments are: Control, an area without agricultural activity; Barrier, a line with elephant grass (Pennisetum purpureum) cultivation; Orchard, composed of rows of fruit trees; and Vegetable garden, composed of rows of trees and vegetables. Soil sampling was performed by collecting 15 individual samples at a depth of 0-20 cm, to create 4 composite samples for each treatment, using a Dutch auger and a 2 mm sieve. Soil biological activity was assessed using Basal Soil Respiration (BSR), by the titrimetric method, determined from the incubation of soil samples in a closed system, with quantification of CO₂ released over the 7-day experimental period. The results were expressed in mg C-CO₂ g soil-1 day-1. The analysis of variance and Tukey's test at 5% probability was performed. The results showed significant differences in CO2 levels produced by microbial respiration between treatments. The Barrier treatment showed the highest average and a significant difference in the statistical test compared to all treatments, with a value of 0.1040 mg C-CO2 g soil-1day-1. The Control and Orchard treatments did not show a significant difference, with rates of 0.0500 mg C-CO2 g soil-1day-1 and 0.0511 mg C-CO2 g soil-1day-1, respectively. The Vegetable Garden treatment showed the second highest average with a value of 0.0751 mg C-CO2 g soil-1day-1.