Location: Sustainable Agricultural Systems Laboratory
Project Number: 8042-12120-001-000-D
Project Type: In-House Appropriated
Start Date: Jul 7, 2016
End Date: Jul 6, 2021
Objective:
Objective 1: Analyze the effects of agricultural management systems on soil biodiversity and functions.
Sub-objective 1.A: Validate combined soil PLFA/metabolomics method for analysis of microbial community structure and function.
Sub-objective 1.B: Analyze soil microbial community structure, diversity, metabolomic profile, and functional diversity in different cropping systems.
Objective 2: Develop improved management practices to reduce emissions of ammonia and greenhouse gases, and reduce pathogens during manure composting.
Objective 3: Develop technologies and practices that improve anaerobic digestion of animal manures and other feedstocks, contributing to improved system economics, recovery of nutrients, and water quality.
Objective 4: Improve the ability to quantify organic contaminants released during the process of water resource recovery, treatment, and reuse of resulting biosolids.
Sub-objective 4.A. Use bioreactors as a model system to measure xenobiotic degradation losses using a newly implemented CAMBI system.
Sub-objective 4.B. Study two specific soluble source tracers, artificial sweeteners for urban sources and metolachlor ethane sulfonic acid for agriculture sources, in order to model nitrogen loading to impacted watersheds.
Approach:
We are developing a new method to simultaneously extract phospholipids and metabolites from soil. Phospholipid fatty acids are measured by gas chromatography while metabolites are measured by gas chromatography-mass spectrometry. Our methods will be tested in a greenhouse experiment using 3 soil types and 3 crop species. We will then analyze soil microbes and their activity using DNA sequencing, transcriptomics, metabolomics, and PLFA analysis in 3 different replicated field trials: the Beltsville Farming Systems Project (FSP), the Beltsville Cover Crop Systems Project (CCSP), and a cover crop field experiment at the ARS lab in Brookings, South Dakota (SD). Composting studies will be conducted at the BARC composting facility. Initial experiments will be conducted outdoors using replicate pilot-scale compost piles composed of manure and bedding from the BARC dairy. Subsequent large-scale experiments will be conducted using extended static piles and windrows of the manure/bedding. Experimental variables include aeration and compost covers. Gases and compost pile temperatures will be monitored. Results will be validated using large-scale extended static piles. Six identical pilot-scale anaerobic digesters will be operated using solids-separated manure effluent from the BARC dairy. For H2S removal experiments, duplicate digesters will be randomly assigned to one of three treatments: no air injection; air injection, low rate; air injection, high rate. Depending on the results, additional experiments may be conducted to evaluate other aeration rates or recirculation of biogas or manure in order to optimize H2S removal. Experiments during the second year of operation will evaluate manure pre-heating as a means to maintain digester temperature and improve overall energy use. The first task will be to establish analytical methods using liquid chromatography-mass spectrometry for up to 53 pollutants. Incubation studies of samples obtained at different stages in the CAMBI process will then be carried out. Based on these results, compounds that appear to be degraded will be singled out for separate individual incubation studies. The goal will be to better describe their degradation rates and formation of metabolites in the CAMBI system. An artificial sweetener will be used as a tool to track urban pollution from wastewater treatment plants while MESA will be used to track agricultural pollutants for rural sources. A liquid chromatography-mass spectrometry method for assessment of both MESA and the most easily detected sweetener will be developed. The second step will be to test the method by analyzing selected real samples. The final step will be to apply the method to base-flow fed streams in the Choptank and Bucks Branch watersheds in Delaware in order to measure groundwater residence times.
