See more from this Division: Joint Sessions
See more from this Session: U.S. Agriculture’s Role in Soil Carbon Sequestration and Greenhouse Gas Mitigation (GRACEnet)
Tuesday, 7 October 2008: 1:45 PM
George R. Brown Convention Center, General Assembly Theater Hall C
Abstract:
This 9 yr field-study, with 3 N-fertility rates, had 2 residue harvesting amounts for corn (Zea Maize) or removal schedules for switchgrass (Panicum virgatum) that were imposed during the final 6 years. The site was near Ithaca, NE on an Aksarben silty clay loam (fine, smectitic, mesic Typic Argiudoll). Soil for chemical and bulk-density measurements were collected from the 0-5, 5-10, and 10-30 cm depths at the beginning of the study and at yrs 3, 6, and 9 by use of a flat-bladed shovel. Following separation of the soil from identifiable plant material, soil organic C was determined using combustion analyses. Depth of soil sampling was a significant source of variation for both the corn and the two switchgrass varieties that were studied. Under corn annual application of 120 kg N/ha resulted in larger amounts of SOC in the 0-5 and 5-10 cm depths, but application of 60 kg N/ha rate resulted in more SOC in the 10-30 cm depth. Corn residue removal decreased total SOC in the 0-5 cm depth. For the Cave-in-Rock' switchgrass variety the 60 kg N/ha resulted in the largest amount of SOC at all 3 depths. Timing of residue removal did not significantly affect SOC within any depth. For the Trailblazer' switchgrass variety the 60 kg N/ha rate resulted in the larger amounts of SOC in the 5-10, and 10-30 cm depths and the August harvest has less SOC than did the October harvest in the 5-10 cm depth. In summary, nitrogen fertilization and sampling depth were important determinants for amount of SOC present at the end of the study, whereas the amount or time of residue removal was less important.
See more from this Division: Joint Sessions
See more from this Session: U.S. Agriculture’s Role in Soil Carbon Sequestration and Greenhouse Gas Mitigation (GRACEnet)