E. Scott Flynn, Charles T. Dougherty, and Ole Wendroth. University of Kentucky, Department of Plant and Soil Science, N-222 Agricultural Science Center N, Lexington, KY 40546
Maintaining forage availability is challenging for managers of grazing systems, especially in spatially heterogeneous swards. Remote sensing may help to overcome this problem. The objectives of this study were to (i) determine if NDVI can be used to assess spatial variability of yield in extensive grasslands, and (ii) to determine if NDVI can be used to evaluate grazing systems. Semivariograms revealed that sampling at a 0.76 m distance provided information about the spatial variability structure of NDVI values from grazed swards. Frequency distributions of sward biomass derived from NDVI reflected foraging strategies of cattle. Negative skewness and high kurtosis of histograms indicated selective grazing, while positive skewness and low kurtosis indicated the opposite. Histograms also allowed for estimation of available forage within each field. We concluded that grassland biomass may be derived from high resolution NDVI and RPM data and used to evaluate condition of grassland landscapes and aid decision-making of managed grazing systems.