Oakes Irrigation Research Site
Carrington Research Extension CenterNorth Dakota State University
P.O. Box 531, Oakes, ND 58474-0531, Voice: (701) 742-2744, FAX: (701) 742-2700, E-mail: Walter.Albus@ndsu.edu

 

STRIP-TILL N RATES, CORN ON SOYBEAN

W. Albus, L. Besemann and H. Eslinger

Results summary

Table 1.  The response of strip-till irrigated corn to fertilizer nitrogen on land previously soybean at the Oakes Irrigation Research Site in 2007.

 

            A strip-tilled corn/soybean rotation was initiated in 2007.  The corn/soybean and soybean/corn treatments are present each year and rotated with each other.  In the corn on soybean year of the rotation, N rates are studied.

 

MATERIALS AND METHODS

 

Soil:

Embden loam and Gardena loam; pH=6.8; 2.5% organic matter; soil-P and soil-K was very high; soil-S was high.

Previous crop:

2006 – soybean and edible bean; 2005 – cabbage, broccoli and pumpkin; 2004 – field corn.

Seedbed Preparation:

Strip-tilled on November 13, 2006, with a shank machine with leading coulters, row cleaners, anhydrous knives and closing disks

Planting:

Planted Midwest 69704 VT3 treated with Crusier seed treatment on April 26 @ 33,000 plants per acre in 30 inch rows.

Plots:

Plots were 35.5 ft long by 15 ft (6 rows) wide.  There were four reps.

Fertilizer:

November 2006, During the strip-till operation applied 15 lbs N/acre and 51 lbs P2O5/acre as 10-34-0.  May 7 applied 35 lbs N/acre as 32-0-0 to all plots except the zero N-rate plots.  June 8 applied 50 lbs N/acre to the 100 lb N-rate plots and 100 lbs N/acre to the 150 lb N-rate plots as 32‑0‑0.

Irrigation:

Overhead sprinkler irrigation as needed.

Pest control:

Aim (⅔ oz/acre) + Glyphosate (2 qt/acre) + NIS (0.5% v/v) + AMS (1 lb/10 gal) on May 9, Lumax (3 pt/acre) on May 16, Cornerstone (32 oz/acre) + AMS (1 lb/10 gal) + Interlock + (4 oz/acre) on May 29,

Harvest:

Hand harvested October 9 and October 10.  Two ten-foot sections from the two center rows from each plot (forty feet of total row).

 

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RESULTS

 

            Previous soybean ground was strip-tilled on November 13, 2006.  Mole knives were set to a 6-inch depth and banded 13 gal/acre of 10-34-00 (15 lb/acre N applied).  The fertilizer N rates were 15, 50, 100, and 150 lb/acre.  There were two 15 lb/acre N rate treatments.  Chlorophyll meter readings were taken on the ear leaves on July 20 and August 16.  Leaves opposite and below the ear were sampled at silking for total N content.  After the corn was mature (R6) eight-inch sections of the stalks were taken at a height six inches above the soil leveland tested for nitrate-N (commonly called the Iowa stalk test).  There are four categories for this test: low (less than 250 ppm), marginal (250-700 ppm), optimum (700-2000 ppm) and excess (greater than 2,000 ppm).

             Yield increased with increased N rates.  Test weights increased with increased N rates above 50 lb/acre.  Soil nitrate-N decreased from 31 lb N/acre in the spring to 17 lb N/acre in the fall.  Stalk nitrate-N was below 100 ppm for all N rates.  This suggests that yield was not maximized at the 150 lb/acre N rate.  Chlorophyll meter readings, leaf N content at silking and grain protein content were good indicators of yield.

 

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Table 1.  The response of strip-till irrigated corn to fertilizer nitrogen on land previously soybean at the Oakes Irrigation Research Site in 2007.

Fertilizer

Yield

Grain

Test

Nitrate-N

Chlorphyll reading1

Leaf-N2

Silking

Stalk

Grain

N Rate

Moist

Weight

Spring-06

Fall-07

7/20/2007

8/16/2007

at silking

date

Nitrate-N

Protein

 

bu/ac

%

lb/bu

lb/ac

lb/ac

--------- # ---------

%

 

ppm

%

 

15

  91

21.8

55.2

35

15

30.5

25.8

1.05

7/21/07

38

5.73

15

  97

21.5

54.9

31

15

31.5

26.6

1.10

7/21/07

40

5.73

50

125

20.6

54.1

28

16

36.2

30.0

1.23

7/17/07

78

5.78

100

172

20.6

55.4

28

17

47.5

38.7

1.65

7/17/07

49

6.08

150

207

20.1

56.9

31

21

54.5

50.2

2.13

7/16/07

96

6.93

 

MEAN

138

20.9

55.3

31

17

40

34.3

1.43

7/18/07

60

6.1

C.V. %

5

5.4

1.0

22.1

30

3.8

5.9

15.40

0.0

47.2

4.5

LSD (0.05)

9.9

1.74

0.8

10.5

8

2.3

3.1

0.3

1.9

43.7

0.4

1Chlorophyll reading taken on the primary ear leaf.
2Leaf-N taken from the leaf opposite and below the primary ear leaf.

 

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