Location: Weed and Insect Biology Research
Project Number: 3060-21220-033-022-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Sep 1, 2022
End Date: Aug 31, 2025
Objective:
The overall goal of the proposal is to evaluate best management practices for improving alfalfa establishment as a cover crop and forage in multi-cropping systems and the mechanisms impacting crop yield, and other ecosystem services such as weed suppression and nitrogen fixation and crop utilization by i) measuring weed pressure, and characterizing crop growth and development, nitrogen use, and yield after interseeding alfalfa with sunflower planted at 30 and 60 inch row spacing or into sorghum at 12 and 24 inch row spacing, and ii), measuring transcriptomic changes to determine, at the molecular level, targets and mechanisms involved in interspecies competition that impact alfalfa establishment and persistence, nitrogen fixation and crop utilization, and crop yield.
The specific objectives relevant to the work ARS investigators will accomplish includes: 1.) in addition to evaluating the impact of interseeding alfalfa on sunflower and sorghum yield, we will determine the benefits that integrating alfalfa in these multi-cropping systems will have on reducing weed pressure; 2.) evaluate the impact that integrating alfalfa into multi-cropping systems will have on the physiological and molecular mechanisms associated with plant-plant interactions leading to altered cover crop (alfalfa) establishment, crop yield, and nitrogen fixation and crop utilization; and 3.) participate in efforts to bridge gaps between science-based results and adoption of new sustainable cropping system practices by growers.
Approach:
Multi-location experiments will be established in North Dakota and South Dakota to evaluate the response that interseeding alfalfa with sunflower or sorghum at different row spacing has on alfalfa establishment, nitrogen fixation and crop utilization, sunflower and sorghum yield, and weed suppression. To determine the impact of establishing alfalfa multi-cropped with sunflower at 30 and 60 inch row spacing or sorghum at 12 and 24 inch row spacing, we will collect above and below ground tissue samples from alfalfa, sunflower and sorghum at various developmental growth stages either mono-cropped or multi-cropped. For molecular studies, samples will only be collected from North Dakota field sites and placed directly into liquid nitrogen and stored at -80 C prior to laboratory extraction of RNA and development of RNA-seq libraries for sequencing at Novogene. All sequence data from field multi-cropping system studies will be analyzed and compared by our research team to help identify signals and processes that could be manipulated to improve alfalfa establishment as a cover crop and forage in multi-cropping systems, improve alfalfa nitrogen fixation and crop utilization, reduce crop yield losses resulting from inter-species competition, and reduce weed pressure in multi-cropping systems. In all experiments, the project team will evaluate N15 abundance to determine how much N is being fixed by alfalfa and the amount, if any, that is transferred from alfalfa to sunflower and sorghum in a multi-cropping system, with a non-fixing alfalfa strip for reference.
