Submitted to: Soil and Water Conservation Society
Publication Type: Abstract only
Publication Acceptance Date: 1/15/2006
Publication Date: 7/21/2006
Citation: Hively, W.D., Lang, M.W., McCarty, G.W., Sadeghi, A.M., Keppler, J., McConnell, L.L. 2008. Remote sensing of cover crop nutrient uptake on Maryland's Eastern Shore [abstract]. Soil and Water Conservation Society. 2008 CDROM. Interpretive Summary:
Technical Abstract: Cover cropping is recognized as an important agricultural best management practice with great promise for reducing nutrient inputs to the Chesapeake Bay. Accordingly, state-run cost share programs have been established to promote cover cropping on farms throughout Maryland. However, current estimates of nutrient leaching reductions associated with winter cover crops are generally based on plot studies extrapolated to the watershed scale based solely on enrollment acreage. Remote sensing provides a tool for real-time estimation of cover crop productivity under various management and landscape conditions. This project used a combination of remote sensing and field sampling to evaluate cover crop productivity and nutrient retention on farms within the Choptank River watershed, a CEAP Special Emphasis research location on Maryland's Eastern Shore. The Maryland Department of Agriculture provided information on farmer enrollment in cover crop cost share programs, including field location, planting date, species, and planting method. Satellite images (SPOT, 10-m resolution) were subsequently used to estimate aboveground biomass on 136 cover cropped fields in winter and spring, with on-farm sampling providing data for calibration of image interpretation and estimation of cover crop nutrient concentrations. Results showed excellent correlation (R2=0.98) between the satellite-derived vegetation index and observed biomass. Planting date, planting method (aerial, drilled, broadcast), cover crop species (wheat, rye, barley), and previous crop (maize, soy) were all significantly correlated with biomass, which ranged from 0 to 60 lb/acre. Early planted crops produced greater biomass, and rye outperformed barley and wheat. Within species the effect of planting method was apparent (drilled outperformed broadcast, and aerial seeded wheat did not perform as well as expected, likely due to dry conditions following seeding). Additional sampling years are necessary to account for effects of climate. The combination of remote sensing, field sampling, and access to farm program documents used in this project proved to be a successful and powerful method for real-time evaluation of cover crop performance on fields subsidized by the cover crop conservation cost share programs, serving to improve understanding of management effects (species, planting date, planting method) on cover crop performance and to promote the most effective cover cropping techniques.