Table 1. Pearson product-moment correlation coefficients (r) among the nitrogen applied, clippings nitrogen content, color intensity, temperature, NDVI measured with a ground-based instrument (Trimble’s GreenSeeker sensor) and NDVI measured with an unmanned aerial vehicle (UAV) on a) Cynodon dactylon x transvaalensis; b) Paspalum vaginatum; c) Zoysia matrella.

In each species correlation coefficients are calculated across all entries.

r	N applied	N (%) clippings	Color intensity (1–9)	Temperature (°C)	NDVI GreenSeeker (780,660)	NDVI UAV (830,660)
a) Cd x t
N applied (kg ha-1)	-	0.94★★★	0.91★★★	NS	0.86★★★	0.91★★★
N (%) clippings	-	-	0.93★★★	- 0.33★	0.91★★★	0.93★★★
Color intensity (1–9)	-	-	-	- 0.29★	0.95★★★	0.96★★★
Temperature (°C)	-	-	-	-	- 0.32★	- 0.34★
NDVI GreenSeeker (780,660)	-	-	-	-	-	0.97★★★
NDVI UAV (830,660)	-	-	-	-	-	-
b) Zm
N applied (kg ha-1)	-	0.94★★★	0.95★★★	NS	0.82★★★	0.79★★★
N (%) clippings	-	-	0.95★★★	- 0.37★★	0.85★★★	0.81★★★
Color intensity (1–9)	-	-	-	- 0.26★	0.86★★★	0.84★★★
Temperature (°C)	-	-	-	-	- 0.34★	NS
NDVI GreenSeeker (780,660)	-	-	-	-	-	0.83★★★
NDVI UAV (830,660)	-	-	-	-	-	-
c) Pv
N applied (kg ha-1)	-	0.93★★★	0.91★★★	NS	0.86★★★	0.79★★★
N (%) clippings	-	-	0.92★★★	NS	0.91★★★	0.87★★★
Color intensity (1–9)	-	-	-	- 0.41★★	0.92★★★	0.90★★★
Temperature (°C)	-	-	-	-	- 0.28★	- 0.28★
NDVI GreenSeeker (780,660)	-	-	-	-	-	0.96★★★
NDVI UAV (830,660)	-	-	-	-	-	-

^★ = Significant at 0.05 level;

^★★ = Significant at 0.01 level;

^★★★ = Significant at 0.001 level; NS = not significant.