Use of Kraft pine lignin in controlled-release fertilizer formulations

Lignin was used as a majority component in a controlled-release fertilizer coating, since this waste product displays properties that make it an ideal substance for application in soil together with conventional mineral fertilizers. Pine lignin marketed under the name of Indulin AT and obtained by the Kraft process was used. Insoluble in water for all pH values that may occur in soil; this product was employed for coating pelleted urea. Seven series of fertilizer were obtained, which also contained various types of rosins and in some cases linseed oil as additives. The physical-chemical evaluation of these fertilizers showed that the most efficient are those whose coating embodies a mixture of dimerized, esterified, and natural rosins, as well as Lignin. It was also demonstrated that the efficiency of the products noticeably increases by adding Linseed oil as a sealing agent.