Temporal Dynamics of Soil Chemical Properties During Incubation with Biochar from Diverse Biomass Sources.

Abstract:

Soil chemical properties degradation is a very serious challenge facing food production in the tropics. To ensure sustainability, there is need for soil improvement. This study aimed at investigating the temporal dynamics of soil chemical properties during incubation with biochar from diverse biomass sources. An incubation experiment was carried out at the Soil Science Laboratory Faculty of Agriculture, Imo State University. The soil used was for the experiment was taken at the depth from 0 - 20 cm from Imo State Teaching and Research farm Owerri. The collected soil was air-dried, crushed, and sieved using 2 mm sieve and characterized before treatments application. Three types of biomass used for biochar production were saw dust, poultry manure and pig dung. The biomasses selected were air-dried before pyrolysis. Prior to the insertion of the biomasses, the biochar machine was first be heated for 10 minutes. 1kg of each agricultural wastes residue was inserted into the modified gas biochar kiln and charred at 300oC for 60 minutes. 500g soil each was placed in plastic container with a lid. The soil was mixed with 5g of the produced biochar each at the rate of 20t ha-1. The detailed treatments used for this experiment were as follows: T1: Saw dust biochar (20 t ha-1), T2: Poultry manure biochar (20 t ha−1), T3: Pig dung biochar (20 t ha−1), T4: 10 t ha−1 of Saw dust biochar + 10 t ha−1 of Poultry manure biochar, T5: 10 t ha−1 of Saw dust biochar + 10 t ha−1 of Pig dung biochar, T6: Control (No biochar amendment). 200ml of deionized water was added for three consecutive days to ensure field capacity is obtained. The containers were cover with lids and strongly tied with black waterproof to maintain dark condition. The incubation experiment was arranged in completely randomized design. Soil samples were collected on days 30, 45, 60 and 75 to analyze its chemical properties The result of the chemical composition of the produced biochar showed that all the produced biochars had an elevated pH and high exchangeable cations with its highest on PMB. The carbon content of the animal based biochars (PMB and PDB) was higher than that found on the plant based biochar (SDB). The nitrogen content followed a reverse trend as seen in carbon content. The results of the biochar application on the chemical properties of the soil showed increase in pH, SOM, TN, Avail P, Exch. Cations and Exch. H with a reduction in Exch. Al. The highest impact on pH, Avail P, Ca, Mg, K and CEC were on soils treated with PMB @ 20t/ha. Soils with SDB @ 20t/ha gave the highest SOM but its combination with PMB (SDB @10t/ha and PMB @10t/ha) gave the highest TN with control exhibiting higher Exch. Al. Despite the increase observed, dynamic changes were observed across the incubation intervals in all the evaluated soil chemical properties.The interaction between biochar from different biomass sources and incubation time underscore the importance of tailoring biochar use to specific biomass and environmental conditions. PMB@20t/ha stand out as the only produced biochar in this study, which not just impact positively on almost all the soil chemical properties evaluated but also maintain a long-lasting effect on the soil. Although, the results from the study showed a clear effect of biochar on soil chemical properties, conducting comprehensive field trials is recommended to ensure that local farmers benefit from this research finding.