1a. Objectives (from AD-416)
To develop comprehensive experimental data sets for testing and improving manure-borne pathogen fate and transport models suitable for nutrient management planning and environmental risk assessment.
1b. Approach (from AD-416)
Field experiments will be performed at the OPE3 field site and the Patuxent runoff site. To (a) evaluate the effect of the buffer strip status on its retention efficiency, (b) develop model parameters and evaluate model performance and (c) evaluate the phosphorus in runoff as a natural indicator of E. coli. The edge-of-the-field conditions will be simulated at the Patuxent site where the manure suspensions will be maniflolded to the simulated vegetated buffer strips with varying soil type, initial soil moisture content, vegetation status, and slope. The rainfall will be simulated to cause runoff that will be collected at the bottom of the strips. Concentrations of E. coli and P will be measured in the runoff transport. Appropriate complementary soil, hydrologic, and microbial measurements will be carried out. The field-scale transport will be studied at the OPE3 site after manure application in accordance with Maryland agronomic rates. E. coli contents will be monitored in manure, in soil, in runoff using automated samplers, in groundwater, and in the first order creek separated from the field with a riparian zone. All experiments will be performed with participation of USDA employees. Cooperator will participate in modeling, data analysis, and publication of results.
3. Progress Report
The research consisted of data analysis and modeling based on experimental data collected during experiments at the OPE3 lysimeter site re-instrumented to simulate the edge-of-field input of manure-borne E. coli to vegetated buffer strips. The experiments were carried out on clay loam and sandy loam soils to evaluate the efficiency of the vegetated filter strips in retaining manure-borne E. coli, phosphorus, and manure particulates, and to provide validation data for the mechanistic sub-model of surface transport of manure-borne E. coli at field scale. The unique dataset contained data on both E. coli runoff and soil concentrations allowing for mass balance calculations and evaluation of retention patterns in space and time. Work progress has been monitored by monthly meetings with UMD counterparts, and weekly group meetings.