1a. Objectives (from AD-416)
The long-term research objective of this project is to develop and translate fundamental agroecological knowledge into recommendations and products to improve the economic position of organic farmers and to improve their ability to meet consumer demand for organic products. Objective 1 is to develop component technologies and management strategies that lead to improved productivity, enhanced soil and water conservation, and efficient nutrient cycling on organic farms. Objective 2 is to understand agroecological principles that drive the function of organic cropping systems and quantify ecosystem services.
1b. Approach (from AD-416)
Approaches to developing component strategies include A) incorporating legumes into organic crop rotations to maximize nitrogen fixation, B) composting that provides a productive and safe amendment for organic agriculture, and C) optimal agronomic practices for managing nutrients and production on organic farms. Approaches to determining agroecological principles include investigating the following variables within the Beltsville long-term Farming Systems Project that compares two conventional and three organic rotations, A) crop performance, B) soil nitrogen dynamics in relation to nitrogen inputs, C) soil carbon sequestration and greenhouse gas flux, D) soil biological community structure in relation to soil quality and production performance, and E) soil erosion and nutrient loss potential.
3. Progress Report
A field experiment to evaluate animal manures and OMRI-approved fertilizers as sources of K and P in organic forage production was established at BARC; a similar on-farm experiment is in its third year. Data are being collected on forage yield and quality, and soil fertility. Sixty-four hairy vetch accessions from around the world are being evaluated for flowering date, biomass production, and nitrogen fixation in the field. Genomic marker analysis (AFLP) shows great diversity among accessions and biogeographical linkages among accessions from the same country of origin. Seed increases of Purple Bounty and/or Purple Prosperity through MTAs with private seed companies facilitated the first field scale trial using these varieties in an organic no-till corn production system. A postdoctoral associate is conducting a second year of field research to address nitrogen availability in organic grain crops. Initial results indicate that soil nitrogen mineralization is substantially greater in organic than conventional cropping systems, and that sidedressing organic materials provides a yield boost to corn compared to applying materials at planting. A four year field trial evaluating the agronomic performance of organic field corn following a hairy vetch cover crop in tilled vs. no-tilled systems is in its final year. Preliminary results suggest delaying hairy vetch termination to optimize N availability can directly impact growing season duration, weed suppressive potential of surface mulches, and subsequent crop performance. Permanent weed-free and weedy check plots were established in organic and conventional systems in the FSP. We are monitoring population and community dynamics and weed-crop competition, and a germinable assay is being conducted to determine long-term persistence of weed seedbanks. Total soil carbon and nitrogen data to a depth of 1 m are being interpreted in light of carbon and nitrogen inputs to soil in the diverse FSP systems. Soils from FSP are also being evaluated for occluded and free particulate organic matter fractions, as part of our effort to evaluate mechanisms of soil carbon sequestration. A Master’s student at Hood College completed their thesis on the global warming potential of FSP cropping systems under the direction of the project’s lead scientist. We are using soil texture data collected at 748 spatially explicit locations at the FSP site to identify sampling locations to measure soil biological properties. We have developed and optimized qPCR and tRFLP methods for FSP soils and are using these methods to quantify and characterize denitrification genes. These data are being compared to measured soil N2O fluxes and other measures of soil microbial community structure.
5. Significant Activities that Support Special Target Populations
Members of this project’s research team participated in planning, organizing, and conducting the 11th Annual Future Harvest-CASA Conference, “Rebuilding the Real Economy: Nourishing Local Foods and Farmers” that was held in Shepherdstown, West Virginia, January 15-16, 2010. This conference targeted small farms, and female and organic producers in the mid-Atlantic area. Minority and disadvantaged farmers in Virginia and North Carolina were the target groups for the 7th Annual Small Farm Family Conference held in Richmond, Virginia, November 9-10, 2009. A project member was instrumental in organizing and planning this conference, and is serving in a similar capacity for the 8th annual “Small Farm Family Conference” to be held November 9-10, 2010 in Williamsburg, Virginia. Members of this project’s research team were instrumental in organizing a workshop on organic grain production in Queen Anne’s County, Maryland, March 9, 2010 and a workshop on organic vegetable production in Baltimore County, Maryland, June 16, 2010.
Teasdale, J.R., Cavigelli, M.A. 2010. Subplots facilitate assessment of corn yield losses from weed competition in a long-term systems experiment. Agronomy for Sustainable Development. 30:445-453.