Properties of Nitrogen-, Potassium-, and Phosphorus-Containing Biocomposite Fertilizers Based on Pine Bark

A method for producing biocomposite fertilizers with increased water resistance, based on the sequential im-pregnation of supports from pine bark with the solutions of urea and potassium dihydrophosphate is proposed. The structure of supports prepared from pine bark and fertilizers based on them was studied by means of scan-ning electron microscopy. The ability of biocomposite fertilizers based on pine bark supports to provide slow outwashing of mineral components with water for a long time was established. The treatment of fertilizers with water at room temperature for 15 days results in the removal of nitrogen, phosphorus and potassium by not more than 34.4, 74.3 and 58.4 wt. %, respectively (of the initial content), which evidences in favour of the prolonged action of biocomposite fertilizers based on pine bark. It is shown that the use of support obtained through ex-traction treatment of pine bark with organic solvents allows making a fertilizer with higher stability against ni-trogen removal with water in comparison with the fertilizer based on the support prepared by treating pine bark with 1 % NaOH solution. Vegetation experiments on germination of Megion oat seeds revealed the same growth-promoting effect of biocomposite fertilizers based on supports obtained using different methods: the length of sprouts and roots increased by a factor of 1.5 in comparison with the reference experiment (water). The studies demonstrated the high potential of the developed fertilizers as an alternative to traditional wa-ter-soluble fertilizers and provided evidence of the possibility to obtain them using either original pine bark or wastes from its extraction processing.