Oakes Irrigation Research Site
Carrington Research Extension Center * North Dakota State University
P.O. Box 531, Oakes, ND 58474-0531, Voice: (701) 742-2189, FAX: (701) 742-2700, email: rgreenla@ndsuext.nodak.edu

Ricky Abrahamson and Larry Cihacek, Soil Science Department, NDSU
Chiwon Lee, Plant Science Department, NDSU


The objectives of this study are:

  1. To optimize nitrogen and potassium levels that enhance sugar content and other quality characteristics of carrots,
  2. To determine the interaction between the fertilizer levels and the yield and quality of carrots grown in commercial fields, and
  3. To develop procedures for efficiently monitoring the nutrient status of the field grown carrots in North Dakota.


Two experiments were conducted to measure the effects of nitrogen and potassium fertilization on carrot yield and quality. Nitrogen (N) rates used were 0, 40, 80, 120, 160, and 200 lb N/acre as ammonium sulfate. Potassium (K) rates were 0, 400, 800, 1200, and 1600 lb K/acre as potassium chloride. Both experiments were conducted using a randomized complete block design with 4 replications. Two rows of carrots, on 22-inch centers, were seeded on each bed. Weed and insect control was as per standard carrot cultural practices.

Carrot petioles were sampled at two week intervals after they had reached the five leaf stage. At the same time, soil samples were taken (from the center of the beds) to a depth of 24 inches. Carrot roots were harvested during the last week of September from a one meter area of each bed.

Carrot petioles were analyzed at sampling for NO3-N and K+ using a Cardy meter. Roots and tops were separated, weighed, and dried for dry matter determination. Both roots and tops will be analyzed for N, P, K, Ca, Mg, S, Na, Fe, Zn, Mn, and Cu. Sugar content of the roots was determined by refractometry. Many of these analyses are currently being done and the data are not available at this time. Root yields for the N and K treatments are shown in Tables 73 and 74.

Table 73. Plot yields of carrot roots as affected by N fertilizer treatment.

N Treatment Plot Yield
lbs/acre Kg/plot
0 8.9
40 8.2
80 9.9
120 10.8
160 12.0
200 10.8

Table 74. Plot yields of carrot roots as affected by K fertilizer treatment.

K Treatment Plot Yield
lb/A Kg/plot
0 10.2
400 8.8
800 9.5
1600 11.6

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