Earthworm population as influenced by soil physicochemical properties and land use types in Makerere University Agricultural Research Institute Kabanyolo.

Abstract

Earthworms, as ecosystem engineers, constitute the most substantial component of animal biomass in soil ecosystems. They play a critical role in numerous essential soil functions, but research that links earthworm populations to specific soil properties is scarce. In this investigation, the effect of soil physicochemical properties and land use types viz. banana, soybean, coffee, maize and fallow field on earthworm populations were assessed at Makerere University Agricultural Research Institute Kabanyolo (MUARIK) located in Kyadondo North, Wakiso district, central Uganda. Earthworms were sampled from three randomly selected points within each land use type for determination of earthworm abundance investigated from early April to early May 2023 by digging out soil blocks measuring 30 cm × 30 cm × 30 cm, earthworms were hand sorted and abundance recorded per ecological group. Soil samples were also obtained from three randomly selected points at the depth of 30 cm for laboratory analysis. The results showed that the lowest mean abundance of epigeic earthworms (4.4 indiv/m2 ) in all sampling points were registered in the soybean field. The highest abundance was found in the banana field (25.9 indv. m-2 ) followed by fallow field. There was also significant difference in the soil physicochemical properties across the land use types with banana field having the highest concentrations of OC (3.536%), K (0.793 cmolc/kg), N (0.356%), P (43 mg/kg), Ca (7.377 cmolc/kg) due to better soil management practices being carried out in the banana field. Epigeic earthworm populations increased with increasing OC and increasing P concentrations. Endogeic earthworm populations increased with increasing epigeic earthworm populations and increasing concentrations of Na in the soil reduced with increasing K concentration in the soil. The association (Pearson Chi Square = 18.21; p = 0.002; df = 8) between epigeic earthworm count category and land use type was significant. The greatest contributor to this significant association was soybean land use type followed by coffee land use type; maize contributed the least to the observed association. The conclusion was that soil management practices greatly affected earthworm abundance in the soils. It is therefore recommended to apply organic residues as mulches and manure while minimizing soil disturbance in order to sustain earthworm populations in soil.