The degree of utilization of nitrogen fertilizers (30–50%) drives to great nitrogen losses with severe economic and environmental problems. The application of polymeric soil conditioners in soil on the other hand results in increased water field capacity, but increases at the same time release rate of fertilizers, thus aggravating environmental impacts due to underground water pollution. In this work the crosslinked sulfonated polystyrene was used as a soil conditioner with three different levels of degree of swelling. Leaching of nitrogen from three different fertilizers was studied after successive rinses with water in soil columns of a height equal to 30 cm. One of the fertilizers was water soluble (conventional) and the other two were controlled‐release fertilizers. It was found that quantities of nitrogen leached in the conventional fertilizer increased with degree of swelling of polymer. Controlled‐release fertilizers proved to be resistant in increased soil moisture due to soil conditioners, thus resulting in reduced leaching. The nitrogen quantities leached from these fertilizers were about half of those leached from conventional fertilizer.