This study aimed to evaluate the short-term impacts of hemp-derived amendments on soil organic matter (SOM) stability, microbial functioning, and carbon–nitrogen cycling across three soil types (Entisol, Alfisol, and Mollisol). We hypothesized that amendment chemistry and soil properties would jointly influence microbial carbon use efficiency (CUE) and short-term carbon sequestration potential. Industrial hemp residue, biochar, and pyrolysis oil were applied at two carbon-equivalent doses (5 and 10 g C kg⁻¹ dry soil) under controlled 120-day incubation conditions. Cumulative CO₂ emissions, dissolved organic carbon and nitrogen, microbial biomass (C and N), SOM stabilization indices, and microbial efficiency metrics (CUE, qCO₂) were quantified. FTIR spectroscopy was used to characterize amendment chemical structures, and multivariate analyses (PCA and hierarchical clustering) were performed to identify treatment–soil interactions. Biochar markedly increased carbon retention and microbial CUE relative to hemp residue and pyrolysis oil, thereby promoting rapid mineralization and higher CO₂ release. FTIR analysis confirmed the presence of stronger aromatic and condensed structures in biochar, indicating greater recalcitrance. Soil type strongly modulated amendment effects: Alfisol exhibited the highest microbial efficiency, whereas Entisol showed the most labile C turnover. Differences were linked to pH, texture, and inherent SOM content. Hemp-derived amendments can enhance short-term SOM stabilization and microbial efficiency, but their effectiveness depends on both amendment chemistry and soil type. Biochar showed the most tremendous potential to improve carbon management, while residue and pyrolysis oil stimulated rapid nutrient cycling. These findings highlight the value of soil-specific strategies when using hemp-based organic inputs to improve soil health. Graphical Abstract Key Insights from the Graph:<UnorderedList Mark="Bullet"> <ItemContent> Hemp Biochar (BC1 & BC2) treatments show the highest carbon sequestration while also reducing CO₂ emissions significantly. </ItemContent> <ItemContent> Hemp Residue (Hemp1 & Hemp2) and Pyrolysis Oil (BC Oil1 & BC Oil2) lead to higher CO₂ emissions, meaning they contribute to short-term microbial activity but not long-term sequestration. </ItemContent> <ItemContent> Microbial efficiency (CUE ratio) is highest in biochar-treated soils, reinforcing its role in long-term carbon stabilization. </ItemContent> </UnorderedList>

Short-Term Effects of Hemp-derived Amendments on Soil C and N Turnover and Microbial Efficiency across Three Soil Types

期刊论文
发表日期：

2026年1月9日

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İbrahim Halil Yanardağ

摘要

This study aimed to evaluate the short-term impacts of hemp-derived amendments on soil organic matter (SOM) stability, microbial functioning, and carbon–nitrogen cycling across three soil types (Entisol, Alfisol, and Mollisol). We hypothesized that amendment chemistry and soil properties would jointly influence microbial carbon use efficiency (CUE) and short-term carbon sequestration potential. Industrial hemp residue, biochar, and pyrolysis oil were applied at two carbon-equivalent doses (5 and 10 g C kg⁻¹ dry soil) under controlled 120-day incubation conditions. Cumulative CO₂ emissions, dissolved organic carbon and nitrogen, microbial biomass (C and N), SOM stabilization indices, and microbial efficiency metrics (CUE, qCO₂) were quantified. FTIR spectroscopy was used to characterize amendment chemical structures, and multivariate analyses (PCA and hierarchical clustering) were performed to identify treatment–soil interactions. Biochar markedly increased carbon retention and microbial CUE relative to hemp residue and pyrolysis oil, thereby promoting rapid mineralization and higher CO₂ release. FTIR analysis confirmed the presence of stronger aromatic and condensed structures in biochar, indicating greater recalcitrance. Soil type strongly modulated amendment effects: Alfisol exhibited the highest microbial efficiency, whereas Entisol showed the most labile C turnover. Differences were linked to pH, texture, and inherent SOM content. Hemp-derived amendments can enhance short-term SOM stabilization and microbial efficiency, but their effectiveness depends on both amendment chemistry and soil type. Biochar showed the most tremendous potential to improve carbon management, while residue and pyrolysis oil stimulated rapid nutrient cycling. These findings highlight the value of soil-specific strategies when using hemp-based organic inputs to improve soil health.

Graphical Abstract

Key Insights from the Graph:

Hemp Biochar (BC1 & BC2) treatments show the highest carbon sequestration while also reducing CO₂ emissions significantly.

Hemp Residue (Hemp1 & Hemp2) and Pyrolysis Oil (BC Oil1 & BC Oil2) lead to higher CO₂ emissions, meaning they contribute to short-term microbial activity but not long-term sequestration.

Microbial efficiency (CUE ratio) is highest in biochar-treated soils, reinforcing its role in long-term carbon stabilization.