USE OF KRAFT PINE LIGNIN IN CONTROLLED-RELEASE FERTILIZER FORMULATIONS

Lignin was used as a majority component in a controlled-release fertil izer coating, since this waste product displays properties that make i t an ideal substance for application in soil together with conventiona l 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 co ating pelleted urea. Seven series of fertilizer were obtained, which a lso contained various types of rosins and in some cases linseed oil as additives. The physical-chemical evaluation of these fertilizers show ed that the most efficient are those whose coating embodies a mixture of dimerized, esterified, and natural rosins, as well as Lignin. It wa s also demonstrated that the efficiency of the products noticeably inc reases by adding Linseed oil as a sealing agent.