CHANGES IN SOIL HYDRAULIC CONDUCTIVITY OF AN ULTISOL IN RESPONSE TO BIOCHAR APPLICATION IN ILE-IFE, NIGERIA.

This study determined effects of wood biochar on soil hydraulic conductivity (k) of two soil
series classified as Ultisol. The experiments were conducted at the Screenhouse of Obafemi
Awolowo University (OAU), Ile-Ife, Osun State, Nigeria. The treatments consisted of four
rates of milled local biochar (0, 450, 900 and 1344 kg/ha) arranged in a Randomized
Complete Block Design with four replicates. Surface (0-15 cm depth) soil of Iwo and Egbeda
soil series were collected from the Teaching and Research Farm, OAU. The experiment was
carried out over a period of 12 weeks in the screenhouse. The antecedent soil properties were
determined in the University’s Soil Science Laboratory and k was determined using disk
infiltrometer. The data generated were subjected to analysis of variance and the significant
means were separated using Duncan’s Multiple Range Test at 95% levels of probability.
Results showed that biochar addition significantly improved soil hydraulic conductivity (K0.5
and K_2 cm at 450 kg/ha and 900 kg/ha) of the two soil series. The peak values for K0.5 (0.013
cm/s) of Iwo series were observed at both 450 kg/ha and 900 kg/ha while it was 0.024 cm/s
for coarser Egbeda series. The highest K_2 cm were 0.009 cm/s and 0.026 cm/s for Iwo and
Egbeda series at 450 kg/ha, respectively. Further, saturated hydraulic conductivity of soil
treated with biochar at 450 kg/ha was one of the highest. Overall, biochar addition at rate of
450 and 900 kg/ha appeared to be more beneficial to adequately improving movement of
water in the soil.