A comparison of remote and proximity sensing tecniques in the monitoring of nitrogen status of turfgrasses

Nitrogen (N) fertilization is a key factor in turfgrass management. The Normalized Difference Vegetation Index (NDVI) is positively correlated with turfgrass health and quality and it is affected by species and fertilization rates. With the aim to test the sensitivity of remote NDVI reading methods in detecting N variation in coolseason and warmseason turfgrass species, data obtained by Satellite and Unmanned Aerial Vehicles (UAV) with a multispectral camera on board and by a ground-based instrument were related and evaluated. The relationship between NDVI value from ground-based instrument and UAV resulted very high for bermudagrass (r=0.96), knotgrass (r=0.91) and tall fescue (r=0.99). Satellite data do not allow an accurate assessment of N plant status of tall fescue (r=0.50). UAV can be used to fill the gap between ground-based measurement and remotely sensed imagery from Satellite platform.