Influence of compost and/or biochar on soil hydrophysical properties of Samaru, Northern Guinea Savanna of Nigeria

Savannah soils are low in organic matter requiring the adoption of practices that increase its soil contents. Compost, biochar, co-composted biochar and compost + biochar effects on soil hydrophysical properties were assessed in screenhouse setting using an Alfisol. The amendments were mixed with 9 kg soil at a rate of 5, 10 and 15 t/ha replicated 9 times replicates giving rise to 117 experimental pots including the control. Pots were arranged in a complete randomized design and 3 replicates from each treatment were destructively sampled and monitored for their saturated hydraulic conductivity (Ks), moisture retention (AWC), aggregate stability (MWD), bulk density (Db) and total porosity (TP) at 4th, 8th and 12th week. Analysis of variance was carried out on the collected data and means were separated at p≤ 0.05 level of probability using Duncan Multiple Range Test. Results indicated that compost at a rate of 15 t/ha significantly (p≤ 0.05) improved Ks by 79.05, 74.62 and 80.37%, while compost + biochar at the same rate increased AWC by 34.02, 38.92 and 40.76%, at 4, 8 and 12 WAS. MWD had increases of 23.11, 31.51 and 31.84% following the application of compost at 15 t/ha. Application of compost + biochar at 15 t/ha lowered Db by 27, 14 and 15.69% compared to the control. Soil TP had increases by 22%, 18% and 27% using 15 t/ha biochar. Therefore, application of biochar at 10 t/ha is recommended in increasing soil hydrophysical properties.