Use of pellets from agricultural biogas plants in fertilisation of oxytrees in Podlasie, Poland

Agricultural biogas plants are not only a place for processing waste resulting from animal husbandry, but also for generating electricity and heat as well as organic fertiliser. In a four-year experiment, pellets were used as organic fertiliser in the establishment of an experiment with fast-growing oxytrees. The study aimed to investigate the growth and stem thickness increment, overwintering in the first and subsequent years of cultivation under the conditions of north-eastern Poland. The dried digestate and the pellets made from it were characterised by a high content of macroelements (N – 1,95%, P2O5 – 1,1%, K2O – 1,3%). The applied pellet from an agricultural biogas plant under oxytree seedlings due to its slow decomposition had a good effect on the growth of oxytrees in the second and third years. The average growth of oxytrees in the second year was 209.7 cm, and in the third year, 246.8 cm. The growth of oxytrees fertilised with pellets made from the digestate of an agricultural biogas plant was 13% higher than that of trees growing on the control strip