Investigation of the technological spring harvesting variants of the industrial hemp stalk mass
Latvia University of Agriculture, Ulbroka, LV-2130, Latvia
One of the simplest technological solutions of hemp harvesting applied in practice in Latvia and some other countries is harvesting of the hemp stalks in spring. Implementation of this technology does not require expensive specialised machinery. However, there are significant losses of the mass and quality of the product. The loss of hemp stalk mass in two-stage harvesting (Option А: harvesting of the seedy part of the yield by means of grain harvesting combines and subsequent gathering of the stalks in spring) constitutes approximately 50–80%. The basic possible solution for reducing these losses is raising the cutting height of the stalks when the seedy part of the yield is harvested. With spring harvesting, Option B, the mass of the stalks is preserved, while the seedy part of the yield is completely lost. A rational solution for spring harvesting can be established by calculations, considering the crop volume and the prices of the seeds and stalks sold, as well as the value of technological losses. In the tests conducted during a subsequent harvest in spring the tensile strength of the fibres of the uncut hemp stalks was 25–52% lower than the strength of the fibres harvested in autumn.