| Popis: |
Assessing strategies to help mitigate the rise in atmospheric CO2 includes evaluation of management decisions concerning tillage practices that influence soil carbon loss. Information is lacking on seasonal CO2 efflux patterns, as affected by degree of soil disturbance/residue mixing and time of tillage operations. An experiment was conducted following a grain sorghum [Sorghum bicolor] (L.) Moench.] crop on a Norfolk loamy sand (Typic Kandiudults) in east-central Alabama to characterize soil CO2 efflux patterns as affected by tillage implement (disk-type, chisel-type, and undisturbed) and time of soil disturbance (fall and spring). Soil CO2 efflux assessment began immediately following fall tillage and continued for a period of about six months. Measures were also taken in the spring after imposing tillage treatments on another set of plots. Concurrent measures were also made on undisturbed plots. For fall measurements, increased CO2 efflux was related to degree of soil disturbance. Losses were similar for the chisel and undisturbed treatments and lower than the disk treatment; cumulative efflux estimates also reflected such differences. With spring tillage, CO2 losses for the undisturbed and disk treatment were similar, while the chisel treatment exhibited a slightly lower loss. Results suggest that selection of fall tillage equipment that maintains surface residue and minimizes soil disturbance could help reduce CO2 loss. However, such considerations for spring tillage operations would not result in a substantial reduction in CO2 loss. |
