Hand-held MARK-II radiometric measurements were used to estimate biomass yields and nitrogen (N) content of Alicia grass (Cynodon spp.) plots having five levels of nitrogen fertilization. The radiometric RED (630- to 690-nm) and NIR (760- to 900-nm) measurements obtained from the plots were converted to reflectance factors and to perpendicular (PVI) and ratio (RVI = NIR/RED) vegetation indices and then correlated with grass biomass yield and N content. The coefficients of determination (r2) in estimating biomass yield for the RED and NIR reflectance factors were 0.04 and 0.73,1 respectively, and for PVI and RVI they were 0.681 and 0.61,1 respectively. The correlations for N content were 0.02, 0.71,1 0.69,1 and 0.60,1 respectively. Since beef cattle protein needs are related to grass N content these results may be useful to operational rangeland remote sensing programs for estimating animal carrying capacity using satellite data.
Journal articles from the Grassland Society of Southern Africa (GSSA) African Journal of Range and Forage Science as well as related articles and reports from throughout the southern African region.