INFLUENCE OF TEMPERATURE ON MICROBIAL ACTIVITIES AND THEIR REACTION TO THE HERBICIDE GOLTIX IN DIFFERENT SOILS UNDER LABORATORY CONDITIONS

Under laboratory conditions three soils taken from long-term agricultural areas were treated with the herbicide ''Goltix WG'' (metamitron). By simulating a penetration of the area-related field dosage into two depths of soil two herbicide concentrations were used. The soils were incubated for eight weeks at constant temperatures (10, 15, 20-degrees-C) and daily fluctuating temperatures (10-20-degrees-C). During this time several microbial activities were investigated like dehydrogenase activity (TTC reduction), enzymes which were related to nutrient cycles, and the nitrogen transformation. The three soils showed different activity levels. The nitrogen mineralization increased with temperature, whereas the other microbial activities were less dependent on temperature and time. After eight weeks depending on the soil some activities were maximum at 10 or 20-degrees-C, whereas others were indifferent. The herbicide mostly caused only weak dose-dependent inhibitions or stimulations after eight weeks. These were modified by the temperature.