Influence of planting geometry of 8-year-old gum-yielding trees on soil chemical properties in the Bundelkhand region

Abstract

Gum-yielding trees, namely Acacia senegal and Acacia nilotica (members of family Fabaceae) are typical plant species of dry areas. These can grow on stressed, degraded and un-utilized soils. Considering the leguminous nature, both species are extensively cultivated in agroforestry systems in India. In Bundelkhand region, acute ecological degradation is prevalent due to deforestation and top soil erosion; however, both the species are thriving well under various land-use patterns. In such areas, planting density or spacing may be a crucial factor, as it not only affects the plant growth but also the soil properties. Hence, a study was carried out to assess the effect of planting spacing (10×10, 10×5 and 5×5 m) of A. senegal and A. nilotica on variations in soil chemical properties at two soil depths (0-15 and 15-30 cm) in Bundelkhand region of central India. Tested plant species, spacing geometry and soil depth showed significant effects on studied parameters. Pooled means of soil pH, electrical conductivity, nitrogen (N), phosphorus (P), iron (Fe) and manganese (Mn) were recorded significantly higher in soil of A. senegal, and zinc (Zn) and copper (Cu) contents in A. nilotica. Values of all the studied parameters were recorded maximum in close spacing (5×5 m) and minimum in wide spacing (10×10 m). Soil organic carbon, N, P, K, Fe, Mn and Cu contents were recorded significantly higher in surface soil layer (0-15 cm), while pH, electrical conductivity and Zn in sub-surface soil layer (15-30 cm). The results of present study clearly suggested that A. senegal and A. nilotica can improve soil health, as both species increased soil organic carbon content up to 22%, N content up to 1 (A. senegal) - 9% (A. nilotica), and P content up to 22 (A. senegal) – 54% (A. nilotica). Study also suggested that 5×5 m spacing can be considered optimum for these species in Bundelkhand region of central India.