Evaluation of a Reduced Cost Active NDVI Sensor for Crop Nutrient Management

Table 1

Calibration stability data for Pocket Sensor #19, testing that slope intercept = 0 and slope = 0 between December 2010 and May 27, 2011.

Data	𝑛	Sensor	Test variable	Estimate	𝑟^2	Pr > ItI	Lower 95%; confidence limit	Upper 95%; confidence limit
6-Dec-10	6	19	Intercept = 0	−0.014	0.987	0.140	−0.032	0.005
6-Dec-10		19	Slope = 1	1.047		0.030	1.005	1.090
14-Dec-10	10	19	Intercept = 0	0.001	0.972	0.965	−0.033	0.034
14-Dec-10		19	Slope = 1	0.999		0.964	0.933	1.064
3-Jan-11	10	19	Intercept = 0	−0.082	0.985	<.0001	−0.113	−0.050
3-Jan-11		19	Slope = 1	1.176		<.0001	1.119	1.233
19-Jan-11	12	19	Intercept = 0	−0.014	0.987	0.204	−0.037	0.008
19-Jan-11		19	Slope = 1	1.059		0.001	1.016	1.102
2-Feb-11	10	19	Intercept = 0	−0.060	0.985	0.000	−0.089	−0.030
2-Feb-11		19	Slope = 1	1.093		0.001	1.041	1.145
21-Feb-11	10	19	Intercept = 0	−0.068	0.983	<.0001	−0.098	−0.038
21-Feb-11		19	Slope = 1	1.069		0.015	1.014	1.124
15-Mar-11	10	19	Intercept = 0	−0.043	0.992	0.000	−0.063	−0.023
15-Mar-11		19	Slope = 1	1.082		<.0001	1.044	1.119
1-Apr-11	10	19	Intercept = 0	−0.094	0.995	<.0001	−0.110	−0.078
1-Apr-11		19	Slope = 1	1.161		<.0001	1.129	1.193
15-Apr-11	10	19	Intercept = 0	−0.067	0.993	<.0001	−0.087	−0.047
15-Apr-11		19	Slope = 1	1.106		<.0001	1.070	1.143
27-May-11	10	19	Intercept = 0	−0.074	0.980	0.000	−0.110	−0.039
27-May-11		19	Slope = 1	1.136		<.0001	1.073	1.199

𝑛: sample size.