Root development as an indicator of soil sustainability of cropping systems in the Atlantic Forest Biome

Abstract

Agricultural sustainability depends on the soil functionality in mechanisms that support plant and animal productivity, water and nutrient cycling, and contamination buffering. Therefore, roots and soil samples from two typical agricultural systems in the Atlantic Forest biome were collected, to evaluate their sustainability through the relationship between roots and soil functionality. The agricultural systems were annual fields as, maize (Zea mays L.) and perennial, palm (Bactris gasipaes K.). The roots were collected from monoliths (48 x 30 x 5 cm) and after, they were gently washed. The root profiles with the IDRISI and SAFIRA softwares were scanned and then analyzed. Soil samples were submitted to evaluations of microbial-C biomass and physical and chemical attributes. The palm field produced more dry matter roots and had greater root area and volume than the maize field (cf. 1.37 versus 0.14 t ha^-1). Considering the 0-5 cm layer, the palm field sustained larger mean weight diameter of soil aggregates (4.2 versus 3.4 mm) and held higher saturation of bases (65 versus 47 %) than the maize. Although the palm field did not have larger total organic C content (20 versus 24 g kg^-1), it stimulated microbial biomass (MB-C; 942 versus 428 mg MB-C kg^-1 soil) and decreased metabolic quotient (0.023 versus 0.034 mg C-CO₂ g^-1 MB-C h^-1) in relation to maize field. This clear relationship between root and soil attributes indicates that better root development contributes to improve soil functionality and for consequence the sustainability of agricultural systems. Therefore, crop systems and soil managements that privilege root growth are better choice to reach the agricultural sustainability.