Decomposition of Hemp Residues in Soil as Facilitated by Different Nitrogen Sources

Improving soil health across agroecosystems has continued to receive attention around the globe, with an emphasis on sustainable organic inputs from agricultural practice. It is well known that different organic materials, such as composts, manure and cereal straws, positively affect soil carbon. The changing agricultural practices have continuously led to new and improved plants in farming. One of these innovative plants is industrial hemp. With the increasing cultivation of industrial hemp globally, the problem of the disposal of hemp residues has been encountered. However, the rich carbon content found in hemp residues in soil is anticipated to enhance the soil quality and address the challenge of effectively utilizing hemp straw. In this study, we conducted a two-way experimental trial to evaluate the decomposition of hemp residues using placement methods (residues incorporated into the soil or left on the soil surface) and nitrogen sources as additives. Different nitrogen additives (nitrogen fertilizer pellets, liquid nitrogen, organic fertilizers, and the preparation “Bioversio”) were selected to accelerate the decomposition of hemp residues. The results showed that the mineralization rates were faster in the residues incorporated in the soil, with a mass loss of over 54% compared to the treatments left on the soil. The influence of additives on the decomposition rates was statistically significant. Additionally, there was a significant increase in the N content in the soil, while the change in carbon content in the soil was not statistically significant. These research results reinforce nitrogen fertilizers’ positive role in accelerating hemp residue decomposition in soil. Furthermore, our findings will help contribute to the effective and sustainable utilization of hemp residues as a bioresource material to improve soil health.