Short-Term Effect of Biochar on Microbial Biomass, Respiration and Enzymatic Activities in Wastewater Irrigated Soils in Urban Agroecosystems of the West African Savannah
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Date
2021
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Abstract
Irrigated urban agriculture (UA) supports the economy and health of urban inhabitants
in low-income countries. This system is often characterized by high nutrient inputs and mostly
utilizes wastewater for irrigation. Biochar has been proposed to increase crop yields and improve
soil properties. In this study, we assessed the transient effect of rice husk biochar (20 t ha−1
) and/or
fertilizer (NPK: 15-15-15) on microbial respiration, microbial biomass carbon and enzyme activities of
irrigated (wastewater and tap water) soil from an UA field experiment in the Guinea savannah zones
of Ghana. Our results showed an increase by up to 123% in soil organic carbon (SOC) after a year of
biochar application, while hot water extractable carbon (HWEC) was increased by only 11 to 26% and
microbial biomass carbon (MBC) by 34%. Basal respiration was significantly increased in mineral
fertilized soil by up to 46% but decreased by 12–45% under wastewater irrigation. Overall, the
metabolic quotient (qCO2
) indicated less stress for the microbial community and increased carbon use
efficiency with biochar application and wastewater irrigation. Total enzymes activity was increased
under wastewater irrigation and biochar treated soils exhibit a more diverse composition of C-cycling
enzymes and a higher activity of aminopeptidases. Biochar and wastewater showed positive effects
on biological soil properties and contributed to soil fertility. Our results suggest beneficial effects of
biochar on non-biochar SOC stocks in the long term.
Description
Research Article
Keywords
urban agriculture, wastewater, biochar, microbial activities, fertilization