|Prior, Stephen - Steve|
Submitted to: Soil & Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2000
Publication Date: N/A
Interpretive Summary: Farm tillage operations can lead to losses of CO2 and water vapor to the atmosphere which can reduce soil carbon storage and available soil water needed for crop stand establishment. Our goal was to determine how four-row planting preparation implements affected short-term water and carbon loss from long-term tilled and residue-covered soil (Norfolk loamy sand). Tilled soil usually had higher losses, but differences due to implement type were small. On residue-covered soil, losses increased as soil disturbance increased. These results indicate that implements which maintain surface residue with minimal soil disturbance can enhance crop production by conserving soil carbon and water.
Technical Abstract: Recent research indicates tillage operations result in a rapid release of CO2 from soil. However, effects of soil disturbance during planting operations on CO2 flux have not been adequately explored. Our objectives were to determine short-term CO2 loss from long-term tilled and residue-covered soil due to use of different planting preparation implements and to characterize spatial changes in CO2 flux. Four-row implements were used on a Norfolk loamy sand. The tilled soil was disk harrowed ten days prior to study; crimson clover (Trifolium incarnatum L.) cover crop in residue areas was killed with herbicide two weeks prior to the study. Due to dry soil conditions, 15-mm of water was applied 24 hrs prior to study. Flux measurements were made with a large canopy chamber (over the center two rows) for an integrated assessment of equipment-induced disturbance; a small chamber was used to characterize positional effects (in-row, trafficked and untrafficked areas) on CO2 efflux only on tilled soil. Irrigation increased gas fluxes for tilled soil. Tilled soil had higher CO2 and water vapor fluxes relative to residue-covered soil except following extreme soil disturbance. In residue areas, gas fluxes were directly related to extent of soil disturbance, but differences due to implement type on tilled soil were small. Comparable CO2 flux patterns were noted between the large and small chamber systems (averaged over positions). On tilled soil, trafficked areas tended to exhibit lower CO2 efflux relative to in-row and untrafficked areas. Results suggests that to conserve soil carbon and water, consideration should be given to selection of equipment that maintains surface residue and minimizes soil disturbance.