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 1.4 million acres in 2006. North Dakota corn production increased from
49 million bushels in 1997 to 156 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 with two plants
coming on line in ND in 2007 plus three additional plants under construction in
ND will change end markets. ND ethanol
producing capacity will increase from 45.5 million gallons in 2006 to 160.5
million gallons in 2007 to a projected 410.5 million gallons in 2008. This 2008 projection would require 147
million bushels of corn or most of the 2006 corn 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. To set the study up correctly corn was
planted on spring strip-tilled soybean stubble in 2006. The rotation will be continuous corn as of
2007. Nitrogen rates in 2006 were 14,
50, 150 and 200 lb/ac.
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.
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rate study
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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. |
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Previous crop: |
2005 - soybean; 2004 - carrot and cabbage;
2003 - field corn, potato and sweet corn. |
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Seedbed preparation: |
Strip till on April 24. |
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Planting: |
Planted on April 25 in 30-inch rows @
35,500 seeds/acre |
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Plots: |
Plots were 140 ft long by 20 ft (8 rows)
wide. There were four reps. |
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Fertilizer: |
On April 25 banded 14 lbs N/acre and 48 lbs
P2O5 as 10-34-00.
On April 28 applied 36 lbs N/acre as 28-00-00 on all plots except the
zero N-rate plots. On June 6 applied
N as 28-00-00 in 50 lb/acre and 100 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 200 lbs/acre). |
|
Irrigation: |
Hand move sprinkler irrigation as needed. |
|
Pest control: |
Lumax + Atrazine (3 pt/acre + 1.6 lb
ai/acre on May 9) Glyphosate Original + NIS + AMS + Interlock (1 qt/acre +
0.05%v/v + 1 lb/10gal + 6 oz/acre) |
|
Harvest: |
Harvested on October 6 with a Gleaner (M2)
combine. Harvest area was the middle
six rows of each plot 119 feet long |
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The lowest N rate was 14 lb N/acre as that
was the amount of N in the 10-34-0 fertilizer applied in the strip-till
operation. Yield increased with
increasing N up to the 100 lb/acre N rate.
Surprisingly the 14 lb/ac N treatment yielded 200 bu/acre. Mineralized N was much higher than normal
due to hot temperatures in June and July, coupled with moist soil conditions
from irrigation. Grain moisture was not
significantly different at the 14, 50 and 100 lb/acre N rates. Moisture content at the 150 and 200 lb/acre
N rates was significantly lower than at the lower N rates. Chlorophyll meter readings on July 17 and
green band color ratings from an aerial picture on August 3, suggested a
tendency for 150 and 200 lb/acre rates to be greener than lower N rates. Visual observations from the combine at
harvest showed the 150 and 200 lb/acre N rates to have a dirty more diseased
look than the lower N rates. One can
only postulate, but it appears that disease levels were higher in the 150 and
200 lb/acre N rates due to a dense green canopy. These resulted in an earlier senescence and drier grain at
harvest.
Yield
increased as chlorophyll meter readings increased from the 14 to the 100
lb/acre N rate. Chlorophyll meter
readings at the 150 and 200 lb/acre N rate were not significantly different than
at the 100 lb/acre N rate and yields were the same. Total N in the leaf opposite and below the ear at the R1 growth
stage were not significantly different at N rate rates above 50 lb/acre. There was a trend for total N to be higher
at the 100 lb/acre N rate compared to the 50 lb/acre N rate.
Green
color reflectivity for treatments was obtained from an aerial color picture of
the plot area on August 3. Each plot in
the picture was delineated. The green
color wavelength in those plots was changed to grey scale. The pictures are digital so they are
composed of many dots called pixels. In
this case each pixel becomes a data point with its own shade of grey. A darker green color in the corn translates
into a darker grey pixel. Adobe
Photoshop software gives each pixel a number for its shade of grey (1=black,
256=white). The software computed an average grey number for each plot that is
shown in Table 29. Since the lighter
the green the higher the reflectivity, lower numbers show a darker green and higher
numbers show a lighter green. Green
reflectivity decreases with increasing N rate up to the 100 lb/acre N
rate.
After
the corn was mature (R6) eight-inch sections of the stalks were taken at a
height six inches above the soil level.
This test is 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 was maximized at a end of season stalk test of 1114 ppm nitrate-N. Stalk test values above that were associated
with a build of fall soil nitrogen.
Increasing
N rates increased grain protein up to the 100 lb/acre N rate. A near linear relationship was found between
pound of fertilizer N applied above the 100 lb/acre N rate and the increase in
fall soil nitrate-N over the spring soil nitrate-N.
Chlorophyll meter readings taken on the ear leaves at silking and green color reflectance from remote sensing on August 3 were good indicators of harvest yield. The corn stalk test was a good indicator of growing season N sufficiency. Stalk tests above 2,000 ppm indicate excess application of nitrogen.
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corn strip-till nitrogen rate study
Table 29. Yield and test data in the Oakes Irrigation Research Site 2006 Corn Strip-Till Nitrogen Rate Study.
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Leaf opposite |
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and below |
Ear leaf |
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Nitrogen rate |
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|
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Spring |
Fall |
ear leaf |
Chlorophyll |
Green color |
Grain |
|
lbs/acre |
Yield |
Moisture |
Test wt. |
Soil Nitrate-N |
Nitrogen |
meter reading |
Reflectivity |
Protein |
|
|
|
bu/acre |
% |
lbs/bu |
---lbs/acre-- |
% |
# |
# |
% |
|
|
14 |
200.0 |
16.5 |
55.8 |
51 |
22 |
1.9 |
48.5 |
136.28 |
7.0 |
|
50 |
216.3 |
16.7 |
56.5 |
48 |
22 |
2.1 |
53.7 |
132.42 |
7.2 |
|
100 |
228.3 |
16.7 |
56.4 |
50 |
33 |
2.4 |
57.3 |
128.84 |
7.8 |
|
150 |
222.8 |
16.1 |
57.3 |
59 |
76 |
2.4 |
57.4 |
126.91 |
7.9 |
|
200 |
223.8 |
15.8 |
56.9 |
50 |
135 |
2.4 |
57.9 |
126.28 |
8.1 |
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|
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|
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Experimental mean |
218.2 |
16.4 |
56.6 |
52 |
58 |
2.2 |
55.0 |
130.15 |
7.6 |
|
LSD (0.05) |
8.4 |
0.3 |
0.8 |
NS |
14 |
0.4 |
2.4 |
2.29 |
0.3 |
|
C.V. (%) |
2.5 |
1.0 |
0.9 |
13 |
16 |
10.4 |
2.8 |
1.14 |
2.6 |
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