ECOLOGICALLY-SOUND PEST, WATER, AND SOIL MANAGEMENT STRATEGIES FOR NORTHERN GREAT PLAINS CROPPING SYSTEMS
Location: Agricultural Systems Research Unit
Title: GREENHOUSE GAS REDUCTION THROUGH AGRICULTURAL CARBON ENHANCEMENT NETWORK (GRACENET)-PROGRESS REPORT
Submitted to: Agricultural Research Service Publication
Publication Type: Other
Publication Acceptance Date: October 24, 2006
Publication Date: October 24, 2006
Citation: Follett, R.F., Johnson, J.M., Parkin, T.B., Smith, J.L., Franzluebbers, A.J., Sainju, U.M., Zobeck, T.M., Collins, H.P., Mikha, M.M. 2006. Greenhouse gas reduction through agricultural carbon enhancement network (gracenet)-progress report. Agricultural Research Service Publication.
Scenario 1 and 2: Evaluate the soil C status and direction of change of soil C in existing typical and alternative agricultural systems:
Conventional tillage and wheat-fallow cropping systems during the last 50 to 100 years have reduced soil organic matter by 30 to 50% of its original level in the Northern Great Plains. Sustainable soil and crop management practices are, therefore, needed to increase soil organic matter and sequester atmospheric C in the soil to sustain crop yields and reduce the concentration of CO2 in the atmosphere. Experiments were conducted in eastern Montana and western North Dakota to evaluate the effects of tillage, cropping system, N fertilization, and irrigation on soil organic and inorganic C. Treatments did not influence soil organic and inorganic C contents at both locations. Averaged across the treatments, organic C contents at 0-5, 5-10, and 10-20 cm depths were 10.2, 8.2, and 14.9 Mg ha-1, respectively, in eastern Montana and 9.2, 9.4, and 17.0 Mg ha-1, respectively, in western North Dakota. Similarly, inorganic C contents at 0-5, 5-10, and 10-20 cm depths were 1.1, 0.8, and 2.2 Mg ha-1, respectively, in eastern Montana and 0.9, 0.9, and 1.5 Mg ha-1, respectively, in western North Dakota.
Scenario 3: Determine the net greenhouse gas emissions of current agricultural systems in existing typical and alternative agricultural systems:
Little is known about the effects of soil and crop management practices in dryland and irrigated cropping systems in the Northern Great Plains. Weekly emission of CO2 was monitored from May to November 2005 in the above experimental plots in eastern Montana and western North Dakota and N2O in eastern Montana using gas chambers. In eastern Montana, dryland soil surface CO2 flux was 1.5 to 2-fold higher under crops than under fallow following sustained rainfall in May and June 2005. Averaged across measurement dates, CO2 flux was 43% higher under cropping than under fallow, 29% higher under nonlegume than under legume crops, and 30% higher with than without N fertilization. Similarly, N2O flux increased with barley, rye, and tilled fallow than with Austrian winter pea and non-tilled fallow from May to July 2006. In western North Dakota, CO2 flux increased by 2 to 2.5 fold immediately after heavy rainfall or irrigation in tilled than in non-tilled treatments applied to areas previously under Conservation Reserve Program (CRP) planting for >20 years. Averaged across measurement dates, CO2 flux was 15% higher in irrigated than in non-irrigated treatment, 59% higher with than without tillage, and 14% higher with than without N fertilization.