Soil quality in citrus tree cultivation in organic agroforestry systems
摘要
The agro-industrial model adopted in Brazil in recent years is based on maximizing production and profit and it is extremely important to propose an agricultural development model based on sustainability. Agroforestry systems (AFS) represent a path towards a more conservation agriculture. Therefore, this study aimed to evaluate the soil quality of an organic agroforestry system used in cultivation of citrus (Citrus sp.) fruits presenting different tree densities. This study was conducted under field conditions of the municipality of Itirapina, Brazil. The soil of the experimental area was classified as Entisols Quartzipsamments. The four treatments were placed in a randomized block design, with three replicates, totaling 12 plots. The treatments were: T1 – Citrus with a density of 446 plants ha−1; T2 – Citrus AFS with a density of 713 plants ha−1; T3 – Citrus AFS with a density of 780 plants ha−1; and T4 – Citrus AFS with a density of 1,040 plants/ha−1. To evaluate soil quality, disturbed and undisturbed soil samples were collected at depths of 0.00–0.10, 0.10–0.20, and 0.20–0.40 m in three agricultural years (2019, 2020, and 2021). The results showed that the effect of natural shading on citrus crops by AFS did not influence the chemical and physical properties of the soil in the evaluated period of three agricultural years. However, after three years, agroforestry systems increased soil organic matter by 45% in the 0–0.10 m layer, raising carbon stocks by 2.77 Mg ha⁻1 year⁻1 and improving fertility (base saturation > 66%, CEC 74.35 cmolc dm⁻3). Soil bulk density increased but remained below critical levels. Penetration resistance decreased by up to 58% in surface layers, indicating improved soil structure.