Soybean root respiration assessed from short-term14C-activity changes

During and immediately after labelling of soybeans (Glycine max. L.) in the field by exposure to14CO2, its respiratory deposit into the soil atmosphere, and its liberation from the soil were used in conjunction with estimates of below-ground plant biomass to apportion total soil respiration. Root respiration of soybean plants at stage V6 was estimated at 4 mg CO2.(g root)−1.h−1. Soil biota, during the same time, contributed 35% of total soil respiration.