Soil microbial activity as influenced by crusted runoff strip length and mulch cover under in-field rainwater harvesting (IRWH)

Abstract

A field experiment was designed to provide insight into the system of in-field rainwater harvesting (IRWH) in determining the effect of microbial activities. The treatments that were evaluated include narrow bare (NB) narrow mulch (NM), wide bare (WB) and wide mulch (WM) runoff strips. Soil samples were collected at depths of 5 and 15 cm from the center section of the runoff area and directly from the rhizosphere of the maize roots around basins. From fresh soil samples, Colony Forming Unit (cfu) readings were taken by using a colony counter and total microbial activity was estimated using the fluorescein diacetate (FDA) hydrolysis method. Community-level diversity physiological profiles of the soil samples were assessed by using Biolog EcoPlates™. Results revealed that the mean values of microbial activity indicated the greatest was found under NM rhizosphere (1.611 ± 0.038) and lowest under WB (0.079 ± 0.005) at 5cm depth. Microbial activity under NM at 5 cm was higher (63% increase) than at the rhizosphere (8% increase). However, there was a decrease in the microbial activity of 17% at 15 cm for WM compared to WB. FDA values were positively correlated with measured soil water content across both 5 and 15 cm depths (r = 0.61 and 0.67) and highly significant (r = 90 at P-value ≤ 0.01) for rhizosphere. Some interesting positive correlations between yield and microbial activity were also found however further investigation on microclimatic aspects in association with microbial diversity and activity on soil surface treatments are important for non-uniform canopy structures of IRWH.