Evaluation of quality indicators in an agricultural soil under the effect of tillage, nitrogen fertilization and crop rotation.

Summary : Biological parameters are used as early indicators of soil quality (ICS) since they respond quickly to anthropic management. The objective of this research was to evaluate the effect of tillage systems (direct sowing – SD and conventional tillage – LC), nitrogen fertilization (N0, N1, N2 and N3) and crop rotation (beans-maize and beans-amaranth) on some physical, chemical and biological indicators of agricultural soil quality. The study was carried out on a Mollisol. Soil moisture content, stable aggregates, pH, particulate organic matter, C:N ratio, organic carbon, microbial biomass, microbial respiration, enzymatic activity were determined. [fosfatasa ácida, hidrolisis de la fluorecín Di acetato (FDA), β-glucosidasa (β- G)] and total glomalin (GT) content. The results showed that acid phosphatase had the highest activity under LC in the bean/corn rotation, FDA responded to the effect of bean/corn rotation at high N levels, the activity of the β-G enzyme was higher under LC in the two rotations; finally, GT responded to the management of SD in the bean-corn rotation. In addition, the analysis of principal components allowed us to infer that all the biological parameters evaluated are ICS. It is concluded that the biological indicators of the soil evaluated were affected by the factors under study.
Biological parameters are used as early indicators of soil quality (SQI) due to their quick response to anthropic management. The objective of this research was to evaluate the effect of tillage system (NT – no tillage and CT- conventional tillage), nitrogen fertilization (N0, N1, N2 and N3), and crop rotation (bean-corn and bean-amaranth), on physical, chemical, and biological quality indicators of an agricultural soil. The study was carried out on a Mollisol. Evaluated indicators were soil moisture,
soil stable aggregates, pH, particulate organic matter, C: N ratio, organic carbon, microbial biomass, microbial respiration, enzymatic activity [acid phosphatase, Fluorecin Di acetate (FDA) hydrolysis activity, β-glucosidase (β-G) and total glomalin content (TG)]. The results showed that acid phosphatase had the highest activity under CT with the bean-corn rotation; the FDA responded to the effect of the bean-corn rotation under high N levels; the β-G enzyme activity was higher under CT with both rotations; finally, TG responded to NT management with the bean-corn rotation. Also, the principal component analysis allowed to infer that all evaluated biological characteristics are SQI. It is concluded that the soil biological indicators evaluated were affected by the studied factors.