Fig. 3. (a) Soil moisture, (b) soil temperature, and (c) CO₂–C emission rate measured in exposed subsoil planted to three cropping systems in 2004: SA is switchgrass burned annually, S5 is switchgrass burned every 5 yr, and CS is corn–soybean rotation with soybean planted in 2004. Soil temperature and soil moisture were measured at the 5-cm depth. * Dates CO₂–C emissions were different at P 0.05.