Spatial dependency of soil chemicals in production systems in the anthropogenic dark earth

In general, anthrosols refer to anthropic soils of high fertility, but the concentration of these nutrients may vary according to the occupation of indigenous people in the past or due to current soil use. This study aimed to evaluate the spatial variability of the chemical attributes of the soil in areas of guandu bean production and pasture and to compare with natural forest systems on anthropogenic dark earth (ADE). For this assessment, 88 sampling points were selected in the area with natural forest vegetation and pasture and 90 sampling points in an area of guandu bean production. Soil samples were collected from layers 0.00–0.05, 0.05–0.10, and 0.10–0.20 m. Chemical analyses of the soil were conducted to determine organic matter, pH, aluminium, soil acidity, phosphorus, potassium, calcium, magnesium, cation-exchange capacity, sum of bases, and base saturation (V%). Data were analyzed using descriptive statistics and geostatistics to sample range, and sample density was estimated for each attribute. Guandu bean showed high content of soil organic matter in relation to pasture in the superficial layer (0.00–0.05 m). Based on sample density, lower variability and higher spatial continuity were observed for guandu bean in relation to pasture and natural forest in the layers of 0.00–0.05 and 0.05–0.10 m. It was found that the use and continuous management of ADE areas alter the content and distribution of soil fertility and, in some cases, may even improve chemical attributes when compared with areas not used with agricultural crops.