TITLE:
Effect of Biochar and Inorganic Fertilizer on Soil Biochemical Properties in Njoro Sub-County, Nakuru County, Kenya
AUTHORS:
Doreen Mbabazize, Nancy W. Mungai, Josephine P. Ouma
KEYWORDS:
Biochar, Inorganic Nitrogen, Phosphorus, Soil pH, Phosphomonoesterases
JOURNAL NAME:
Open Journal of Soil Science,
Vol.13 No.7,
July
7,
2023
ABSTRACT: Declining soil fertility is a major constraint to potato farming, the second most important food crop in Kenya. The objective of the study was to determine the effect of different rates of biochar and inorganic fertilizer on some soil properties; soil pH, soil phosphomonoesterases, inorganic nitrogen and extractable phosphorus. The study was conducted for two seasons (short and long rains) at two locations (Egerton University agricultural field and farmer’s field in Mau Narok) using a split-plot design in a randomized complete block (RCBD) arrangement with variety as the main plot and soil amendments as the subplot. Biochar and Diammonium Phosphate (DAP) at 0, 5, and 10 t⋅ha−1 and 0, 250, and 500 kg⋅ha−1 respectively, were applied, resulting in nine treatment combinations. Two potato varieties (Shangi and Destiny) were used in the study. A combination of 5 t⋅ha−1 biochar and 500 kg⋅ha−1 DAP and sole application of biochar at 5 t⋅ha−1 resulted in an increase of 1.25, 2.54 units in soil pH in two seasons, respectively. Similarly, a combination of 5 t⋅ha−1 biochar and 250 kg⋅ha−1 DAP increased soil available phosphorus by 105 units from 30.7 mg⋅kg−1 to 136 mg⋅kg−1. The application rate of 5 t⋅ha−1 biochar with 250 or 500 kg⋅ha−1 DAP significantly increased soil nitrate by 102.11 and 116.14 units, respectively. Soils amended with biochar at 5 t⋅ha−1 combined with 500 kg⋅ha−1 DAP, 10 t⋅ha−1 of biochar combined with either 250 kg or 500 kg of DAP gave the highest alkaline enzymes (mM pNP × kg−1 × h−1). However, the highest acid soil phosphomonoesterases were obtained under the sole application of DAP at 500 ha−1. Thus, using biochar with chemical fertilizer seems a plausible option to ameliorate the declining nutrient base of farmland in Kenya, which could sustainably support potato growth.