Document Type : Research Paper
Authors
1
PhD student Department of Soil Sciences, Faculty of Agriculture, University of Zanjan, Zanjan, Iran,
2
Department of Soil Sciences, Faculty of Agriculture, University of Zanjan, Zanjan, Iran,
3
Department of Chemistry, Faculty of Science, University of Maragheh, Maragheh, Iran, 55187-79842.
4
Department of Agriculture, Payame Noor University, Tehran, Iran
Abstract
Soil microorganisms play a vital role in nutrient cycling and biochemical processes, with their activity largely dependent on the availability of carbon sources. This study compared the effects of activated biochar and hydrochar derived from Chlorella vulgaris on soil biological properties and enzyme activities at concentrations of 0.5% and 1%. The experiment consisted of three components: (1) measurement of microbial respiration over 90 days, (2) monitoring of soil pH and microbial populations over 12 weeks, and (3) evaluation of enzyme activities (alkaline phosphatase, acid phosphatase, arylsulfatase, β-glucosidase, invertase, protease, and dehydrogenase) and microbial characteristics at the end of week 12. Microbial respiration in the biochar treatment began at 315.33 mg CO₂ kg⁻¹ dry soil day⁻¹, showing a sharp decline by day 11, followed by a gradual decrease. The highest arylsulfatase activity (286 µg PNP g⁻¹ soil h⁻¹) was observed in the 0.5% hydrochar treatment, while the control exhibited the lowest value (166 µg PNP g⁻¹ soil h⁻¹). Soil pH initially increased in the hydrochar treatment but decreased at the end of the experiment in the biochar treatment. Both amendments enhanced microbial biomass carbon and enzyme activities, with hydrochar demonstrating a more pronounced effect. These findings indicate that hydrochar may serve as a more effective soil amendment than biochar in improving microbial respiration, enzyme activities, and microbial diversity.
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