Biochar increases soil microbial biomass with changes in extra- and intracellular enzyme activities: a global meta-analysis

Abstract

Biochar application to soil has been proposed as a potential management strategy to enhance soil carbon (C) sequestration, reduce greenhouse gas emission, improve soil quality, and increase crop productivity. The effects of biochar on soil microbial and enzyme activities are integrally linked to the potential of biochar in achieving these benefits. We conducted a global meta-analysis to assess the effects of biochar on soil microbial biomass C and nitrogen (N) and the activities of 12 enzymes, and identify key factors affecting those soil microbial properties using 964 data points from 72 papers. We found that biochar effects on enzyme activities vary widely with soil type, biochar property and the type of enzyme studied. Biochar significantly increased microbial biomass C (MBC) and urease, alkaline phosphatase and dehydrogenase activities by 21.7%, 23.1%, 25.4% and 19.8%, respectively, with no significant negative effects on any of the enzymes analyzed in this study. Biochar application was more effective in increasing MBC and enzyme activities in soils with low pH (< 6.5), TC (< 20 g kg −1 ), TN (< 2 g kg −1 ), and a fine texture (including clay, clay loam and silt clay). Biochars produced at pyrolysis temperature of 350-550 °C with a high pH (> 10) and low C/N ratio (< 50) increased MBC and urease and dehydrogenase activities. Biochar increased MBC and N-acquisition enzyme activities in the field but not in lab incubation experiments. Urease was increased in short-term studies (within 100 days of biochar application) while alkaline phosphatase was increased in long-term studies that span more than 1 year. The increase in MBC and activities of some soil enzymes in response to biochar application with no negative effects on any hydrolytic and oxidative enzymes illustrate its potential to enhance soil quality particularly in the degraded soils with low nutrient availability and fertility due to limited soil microbial and enzymatic activities. This study also shows that biochars can be designed to achieve specific properties for enhancing microbial and enzymatic activities for specific soils.

Efficiency of Wheat Straw Biochar in Combination with Compost and Biogas Slurry for Enhancing Nutritional Status and Productivity of Soil and Plant

“…The correspondence analysis also revealed that improvement in soil properties such as EC, SOC, P, K, and CEC plays a dominant role in improving the soil enzyme activity. Pokharel et al [90] also observed that different levels of biochar increased UA in the soil. In another study by Mehmood et al [91], UA in the soil after 60 and 120 days of sugarcane residues biochar (10 t ha −1 ) application increased by 7.9 and 12.7% over control.…”

Biochar and compost effects on soil microbial communities and nitrogen induced respiration in turfgrass soils

“…Our results revealed that UA, DHA, and BGA enzyme activities were not affected by biochar application alone but adding compost greatly enhanced their activity. While many studies have shown enhanced enzymatic activity in response to biochar [ 74 , 75 ], these results were typically collected within 100 days of biochar application. The 6-month period between biochar application and soil enzyme analyses conducted in this experiment may have contributed to a lack of significant impact of biochar alone.…”

Irrigation Water Saving of Date Palm Tree Plantations Using Soil Amendments in UAE

“…Critical to further advances is the recognition and reporting of the diversity of biochars. (Lehmaan, et al 2011, andPokharel et al 2020).…”

“…Hence, farmers often face extreme poverty in drought-prone areas. Efficient water use techniques are very important in the face of climate change, (Sohi et al 2010, Clawston et al 2014, Barrow 2012and Khanmohamadi et al 2015 discourage deforestation and preserve cropland diversity (Yu et al 2013, Muhamad et al 2018, Badawi 2019 and Pokharel et al 2020).…”