Guiding fall fertilization of cool-season turfgrass lawns with NDVI sufficiency index

Abstract

Fall N fertilizers are applied to turfgrass at predetermined rates instead of being based on plant-N status. Normalized difference vegetative index (NDVI) and the sufficiency index (SI) concept are used to assess plant-N status in some agronomic crops but has not been evaluated for turfgrass. This study was conducted across 3 yr in Connecticut to determine fall and spring NDVI SI values in a mixed species, cool-season lawn. Field experiments were set out with varying fall N rates with NDVI measured weekly in October and November, and in late April. Quadratic and Linear-Response and Plateau (LRP) models were significant (P 89% of spring N-rich reference would indicate that excess fertilizer was applied the previous fall at rates >49 kg N h−1. The NDVI SI can provide site-specific fall N fertilization guidance of cool-season turfgrass lawns.