Effect of Incubation of Biochars Amendment on the Chemical Properties of Acidic Soil

Abstract

Biochar is considered as universal conditioner to improve soil quality, but its effect on different soil types and rates on soil properties,bacterial community and plant growth are still unclear,particularly in the typical acid soil in southeastern Nigeria. This study was done to know the changes in soil chemical composition which could be caused by dissolution and release of nutrients from biochar in an incubation experiment. The study was conducted during rainy season in 2022 in Sobioma Agro Farms LTD using loamy sand with acidic pH (5.7). The soil were collected from the same farm. Soil was filled in separate plastic bucket with lid (2kg capacity) and treatments imposed as per the treatment details; T1: Corn Cob charred for 60 minutes @ 20 t ha-1 T2: Rice husk charred for 60 minutes @ 20 t ha -1 and T3: Poultry manure charred for 60 minutes @ 20 t ha-1. The treatments were replicated thrice, then repeated for different days of incubation (15,30 and 45days respectively). The experiment was laid out in a completely randomized design (CRD). In this study, the biochar carbon content and Total N ranges from 95.9 to 181.4 gkg" 1 and 5.2 to 8.9 gkg' 1 respectively with the highest values on rice husk biochar (Table 3). Poultry manure showed highest significant (P O.05) effect in Cu (1.61 mgkg- 1), Mn (5.26 mgkg- 1 ) and Fe (6.54 mgkg 1 ) compared to rice husk biochar and corn cob biochar (Table 4). The Cations Exchange Capacity (CEC) and base saturation (BS) increased after amendment of the acidic soil with PMB (5.51 cmolkg' 1 and 85.4% respectively).
 The results revealed that, application of different biochar increased the pH and other soil chemical properties evaluated with slight increase only in exchangeable k and Na and a decrease in exchange acidity (A l and H) of soil. During the incubation experiment changes were noticed, some nutrient element showed a continuous increase with incubation time (exchangeable Al and H in Corn cob and poultry manure biochar respectively) while some reached its maximum at the mid incubation time (CEC, BS, TN, Av.P and OM in poultry manure biochar). In some cases a decline was observed up to the mid incubation period after which an increase was observed (Exchangeable Ca and Mg in corn cob biorchar and Exchangeable k and Na in Rice husk buiochar). This work stresses the importance of biochar to soil quality improvement.