Effect of four nematocides on activities of microorganisms in soil.

Tests were conducted to determine the effects of four nematocides, Dasanit, carbofuran, D-D, and Vorlex on microbial activities in a loamy sand. The results indicated that bacterial and fungal populations initially decreased with some nematocide treatments but recovered rapidly to levels similar to those in the controls. In some instances, ammonium production from added peptone increased in the nematocide-treated soils, whereas mineralization of soil organic nitrogen and nitrification and oxidation of elemental sulfur were depressed. Oxygen consumption generally increased in proportion to the concentration of nematocide in the soil. However, with Vorlex, an increase in respiration was evident at the lower concentration, whereas an inhibitory effect occurred at the higher concentration. The study indicated that indigenous soil microorganisms can tolerate these chemicals used for control of nematodes in soil.