Oakes
CORN STRIP-TILL NITROGEN RATE STUDY
W. Albus, L. Besemann and H. Eslinger
Corn grain production has made amazing increases in both
yield and number of acres planted ND in the past 10 years. Corn acreage in ND has increased from about
592,000 acres in 1997 to 2.6 million acres in 2006. North Dakota corn production increased from 49 million
bushels in 1997 to 279 million bushels in 2006.
Southeastern ND has historically been a large exporter of
corn out of state. This is evidenced by
several 110-car unit-train loading facilities in the area. The expansion of ethanol plants in northern
SD along new plants coming on line in ND will change end markets. Ethanol producing capacity in ND is
projected to be 410.5 million gallons in 2008.
This 2008 projection would require 147 million bushels of corn or 53
percent of the 2007 crop.
Obviously, corn acres must increase in ND. Increasing corn acres in SE ND will require
more continuous corn in crop rotations.
Conventional grown continuous corn requires extensive tillage with high fuel
use. Continuous corn requires about 40
lb more N/acre than corn grown on soybean ground. Fuel and fertilizer prices have increased dramatically with
higher energy costs.
It is the objectives of this study to grow continuous corn
in a strip-till system that eliminates full width tillage and to find efficient
nitrogen rates.
We would like to thank Pro Ag Supply
Inc of Aberdeen, SD for their support.
A special thanks goes to Nate Kemp, agronomist with Pro Ag for his
assistance at harvest.
|
Soil: |
Embden sandy loam and Helca sandy loam; pH=6.8; 2.4%
organic matter; soil-P and soil-K was very high; soil-S was medium. |
|
Previous crop: |
2006 - field corn; 2005 - soybean; 2004 - carrot
and cabbage. |
|
Seedbed preparation: |
Strip-tilled on November 6, 2006, with a shank machine
with leading coulters, mole knives and closing disks. . |
|
Planting: |
Planted on April 28 in 30-inch rows @ 29,000
seeds/acre. |
|
Plots: |
Plots were 140 ft long by 20 ft (8 rows)
wide. There were four reps. |
|
Fertilizer: |
On November 6, 2006 when strip-tilled banded 12
lbs N/acre and 42 lbs P2O5 as 10-34-00. On May 7 applied 38 lbs N/acre as 32-0-0
on all plots except the zero N-rate plots.
On June 8 applied N as 32-0-0 in 50 lb/acre increments for a total of
100, 150 and 200 lbs total N/acre on the respective N-rate treatments (0, 50,
100, 150 and 2001
lbs/acre). |
|
Irrigation: |
Hand move sprinkler irrigation as needed. |
|
Pest control: |
Lumax (3 pt/acre) on May 16, Cornerstone (32
oz/acre) + AMS (9.5 lb/100 gal) + Interlock (4 oz/acre) on May
29. Reps 1 and 2 only; Status (5
oz/acre) + AMS (10 lb/100 gal) + NIS (1 qt/100 gal) on June 5. |
|
Harvest: |
Harvested on October 15 with a Gleaner (M2)
combine. Harvest area was the middle six
rows of each plot 137 feet long. |
1The 200 lb/ac N rate actually received 150 lb/acre
total N because it had 59 lb/acre N more soil N than the 150 lb/acre N rate.
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Previous
corn ground was strip-tilled on November 6, 2006. Mole knives were set to a 6-inch depth and banded 10.7 gallon of
10-34-0 fertilizer (12 lb/acre of N applied).
Nitrogen rates were 12, 50, 100, 150, and 200 lb/acre. The 200 lb/acre N rate actually received 150
lb/acre of fertilizer N. The rational
for this was that the 2006 fall nitrate-N content in the 200 lb/acre N rate
plots was quite high at 135 lb/acre and was 59 lb/acre higher than the 150
lb/acre N rate plots. It didn’t seem
logical to apply another 50 lb/acre of N when the 200 lb/acre N rate plots
already tested 59 lb/acre higher.
Chlorophyll meter readings were taken on the ear leaves at silking 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 level and 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).
Corn
yield increased with increasing rate of N up to the 150 lb/acre rate. Test weights tended to increase with
increasing N rates. Soil nitrate-N
content in the fall showed a surprisingly large drop in the 150 and 200 lb
N/acre plots as they decreased 58 and 115 lb N/acre,
respectively. Low fall soil N levels,
even at the 200 lb/acre N rate (20 lb N/acre), are substantiated by the very
low nitrate-N content in the mature stalks.
A stalk nitrate-N test of only 137 ppm at the 200 lb/acre N rate
suggests that yield was not maximized.
Chlorophyll meter readings on July 23 and August 16, imply otherwise. Chlorophyll meter readings for both dates
show the 150 lb/acre N rate readings to be 99% of the 200 lb/acre N rate. Leaf N content at silking and grain protein
was maximized at the 150 lb/acre N rate.
Go
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Table
1. The response of strip-till irrigated corn,
on land previously corn, to nitrogen fertilizer in the Oakes Irrigation
Research Site 2007 study.
|
N Rate |
Yield |
Grain |
Test |
Fall
nitrate-N |
Chlorphyll reading1 |
Leaf-N2 |
Silking |
Stalk |
Grain |
||
|
Moist |
Weight |
2006 |
2007 |
7/23/2007 |
8/16/2007 |
at silking |
date |
Nitrate-N |
Protein |
||
|
|
bu/ac |
% |
lb/bu |
------ lb/ac ------- |
--------- # --------- |
% |
|
ppm |
% |
||
|
|
|||||||||||
|
12 |
83 |
19.2 |
55.2 |
22 |
13 |
30.1 |
26.4 |
1.2 |
7/25/07 |
45 |
5.8 |
|
50 |
113 |
19.1 |
54.0 |
22 |
11 |
37.2 |
31.7 |
1.4 |
7/22/07 |
41 |
6.0 |
|
100 |
166 |
19.2 |
55.2 |
33 |
16 |
49.3 |
45.2 |
1.8 |
7/21/07 |
46 |
6.2 |
|
150 |
198 |
18.8 |
57.2 |
76 |
18 |
56.0 |
55.7 |
2.4 |
7/20/07 |
91 |
7.3 |
|
200 |
200 |
18.7 |
57.6 |
135 |
20 |
56.2 |
56.0 |
2.2 |
7/20/07 |
137 |
7.3 |
|
|
|||||||||||
|
MEAN |
152 |
19.0 |
56.0 |
58 |
15 |
45.8 |
43.0 |
1.8 |
7/22/07 |
72 |
6.5 |
|
C.V.% |
3.1 |
2.5 |
0.5 |
16 |
20 |
2.9 |
3.0 |
15.2 |
0.0 |
47 |
3.7 |
|
LSD (0.05) |
7.2 |
NS |
0.4 |
14 |
5 |
2.1 |
2.0 |
0.4 |
1.2 |
52 |
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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nitrogen rate study
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