Optimum range of nitrate-nitrogen concentrations (dry weight and sap basis) in potato petiole at various stages of growth. Dry weight basis
Stage of growth (days after emergence)	Norkotah Norland Atlantic Kennebec	Shepody R. Burbank Snowden	Onaway Superior
dae	% NO3-N
30	2.5- 2.8	2.0 - 2.3	2.3 - 2.5
40	2.3- 2.5	1.7 - 2.2	2.0 - 2.3
50	1.8- 2.3	1.2 - 1.b	1.5 - 1.9
60	1.3- 1.9	0.8 - 1.1	0.9 - 1.2
70	0.8- 1.1	0.5 - 0.8	0.4 - 0.6
Dry weight basis
Stage of growth (days after emergence)	Norkotah Norland Atlantic Kennebec	Shepody R. Burbank Snowden	Onaway Superior
dae	ppm NO3-N
30	1900 - 2100	1600 - 1800	1800 - 1900
40	1800 - 2000	1600 - 1700	1600 - 1800
50	1400 - 1800	1000 - 1300	1200 - 1500
60	1110-1500	700-900	500-1000
70	700-900	500-700	400-600
Values from the Cardy can be converted to dry tissue calibration by using the equation: % dry weight NO3-N = 0.00142 (ppm sap NO3-N) -0.21

PETIOLE N03-N SUFFICIENCY LEVELS (Source: University of Minnesota)
		Petiole NO3-N (ppm)
Crop	Growth Stage	Dry Tissue	Fresh Sap
Potatoes - Russet Burbank	Early vegetative/ tuberization	17,000 - 22,000	1,300 - 1,600
	Mid Tuber growth/ bulking	11,000 - 15,000	900 - 1,200
	Late Tuber growth/ maturation	6,000 - 8,000	550 - 700

PETIOLE N03-N SUFFICIENCY LEVELS (Source: Michigan State University) The following guidelines are based on one year's research results and will be revised as necessary based on future research findings.
CARROTS
Carrot Root Size (y)	Adequate Petiole Sap Nitrate Concentration (z)
	Nitrate-N	Nitrate
(Inches)	(ppm)	(ppm)
Prior to Sizing	750 +	3,300 +
Up to 0.25	550 +	2,420 +
0.25 to 0.50	450 +	1,980 +
0.50 to 0.75	300 +	1,320 +
0.75 to 1.50	250 +	1,100 +
> 1:50	200 +	880 +
(y) Diameter at the shoulder (z) Youngest fully elongated petiole

CELERY
Weeks After Transplanting	Adequate Petiole Sap Nitrate Concentration (z)
	Nitrate-N	Nitrate
	(ppm)	(ppm)
Up to 5	800 +	3,520 +
5 to 6	725 +	3,190 +
6 to 7	650 +	2,860 +
7 to 8	575 +	2,530 +