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:
Field experiments to evaluate animal manures and OMRI-approved fertilizers as sources of K and P in organic forage production are in their third year. We have cloned and sequenced five key flowering control genes from eight representative hairy vetch genotypes that differ in flowering time, information that could be used by crop breeders. The automated electronic control system for aeration supply for an in-vessel composting system was brought up to a fully operational status and two test batches were completed. Field studies comparing survival of generic and non-pathogenic strains of E. coli in soils managed organically and conventionally were initiated with poultry litter, dairy manure solids, dairy manure liquid and horse manure to compare baseline responses before composts made of these materials are introduced. Cacao pod husks, an organic residual typically left in the field after cacao beans are harvested, were evaluated as a potential source of compostable feedstock for use in producing an organic fertilizer for cacao farmers. Data are being collected for a third year in permanent weed-free and weedy check plots in organic and conventional systems in the FSP. We are monitoring population and community dynamics and weed-crop competition. A germinable assay is being conducted to determine long-term persistence of weed seedbanks. A University of Maryland student has completed the experimental phase of a project evaluating the influence of long-term soil management on weed-crop competition relationships. Two Master’s students at the University of Maryland are compiling 14 years of data to compare nutrient budgets (C,N,P,K) and evaluate carbon and nutrient management among cropping systems at the long-term FSP. A Brazilian PhD student is characterizing soil carbon fractions collected from diverse FSP systems using near infrared, mid infrared and pyrolysis spectra as part of our effort to evaluate mechanisms of soil carbon sequestration. A scientist from Brazil (EMBRAPA), in association with colleagues at the University of New Hampshire, is comparing output from the DNDC model with two years of soil N2O emissions data to evaluate model predictions. A University of Maryland Master’s student is evaluating the impact of cover crop mixes (rye, hairy vetch) and manure sub-surface banding on soil N2O emissions. The lead scientist is collaborating with scientists from Princeton University to compare a laser based method of measuring atmospheric N2O concentrations with the standard GC method. The lead scientist is collaborating with scientists from the University of Maryland to compare N2O emissions from organically-managed eggplant grown using four different cover crop practices. A visiting Brazilian PhD student is measuring soil N2O emissions following application of a conventional and a newly-designed slow-release nitrogen fertilizer. A high school intern is characterizing short term dynamics of N2O emissions from soil to better characterize factors controlling N2O emissions in the field.