The effect of agronomic management of hemp (Cannabis sativa L.) on stem processing and fibre quality

Hemp (Cannabis sativa L.) is a multi-purpose crop that finds applications in technical textile, paper, food, cosmetic and automotive industries. Due to the increasing demand for sustainable fibres, the hemp fibre sector is expected to grow in the future. However, overall information on the effect of agronomic practices on decortication efficiency and hemp fibre quality traits is very limited. This study aims to evaluate the relationship between agro-technique, decortication process, and energy consumption properties. In this paper, four planting densities, four levels of nitrogen fertilisation and two harvesting times were compared in different environments to evaluate the effect of agronomy on stem and fibre processing properties, including energy requirements, using a lab-scaled hemp stem decorticator. The present work highlights that the optimal plant density and nitrogen fertilisation levels to reach high decortication efficiency are 120 plants m−2 and from 0 to 100 Kg N ha−1, respectively. The effect of nitrogen and density on the considered properties is mediated by their influence on stem diameter. The highest decortication efficiency and the highest efficiency in energy use were observed at full flowering. On the contrary the fineness of the fibre, which was only evaluated in one environment, was highest in stems harvested at seed maturity, in particular when plant densities above 120 plants m−2 and when 60–100 Kg N ha−1 were applied. The methodology used in this work effectively evaluates the impact of agro-technique on the efficiency and energy requirements of hemp decortication.