Alginate and lignin-based formulations to control pesticides leaching in a calcareous soil.

Important risk of groundwater pollution has been observed as a result of rapid leaching of highly soluble pesticides when used in agronomic practices as conventional formulations. This risk can be minimized through the application of the pesticide at a set rate using controlled release formulations (CRFs). In this research, CRFs of isoproturon, imidacloprid and cyromazine have been evaluated in a calcareous soil. The effects of two natural polymers (alginate and lignin) and two modifying sorbents (bentonite and activated carbon) on pesticide release kinetics from CRFs have been investigated, as well as mobility of pesticides using soil columns. The rate of pesticide release in soil from CRFs diminished in all cases in relation to technical products. From the analysis of the time taken for 50% of the active ingredient to be released into soil (T(50 soil)), it can be deduced that the release rate of pesticides can be controlled by using activated carbon in the alginate-based CRFs and mixing the pesticide with kraft lignin. Mobility experiments showed that the use of CRFs clearly reduces the presence of isoproturon and imidacloprid in the leachate compared to technical products, and to a lesser extent for cyromacine due to its high water solubility.