use of alternative concepts for determining preplant and mid-season n rates
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Use of Alternative Concepts for Determining Preplant and Mid-Season N rates. Hodgen and Schepers 2007. Late emerging corn plants were non-responsive to different N fertilizer management strategies employed in this study. - PowerPoint PPT PresentationTRANSCRIPT
Use of Alternative Concepts for
Determining Preplant and Mid-Season N rates
Use of Alternative Concepts for
Determining Preplant and Mid-Season N rates
Hodgen and Schepers 2007Hodgen and Schepers 2007
• Late emerging corn plants were non-responsive to different N fertilizer management strategies employed in this study.
• Managing N inputs per plant can increase NUE by 23% over broadcast applications of 168 kg N/ha applied either preplant or midseason (V9) and maintain yield and grain production per plant.
Hodgen and Schepers, 2007Hodgen and Schepers, 2007
• Opportunities may exist to increase N use efficiency by capitalizing on detecting the variability of N demand per plant as indicated by differences in grain production within commercial fields.
• Ultrafine spatial N management schemes that are aimed at increasing NUE should operate at a resolution which reflects the horizontal diameter at which plants obtain the majority of their N supply.
Hodgen and Schepers, 2007Hodgen and Schepers, 2007
• Similar N management techniques that attempt to capitalize on detecting differences in biomass (leaf area) production midseason could be used to estimate the relative yield differences between plants because of corn plants’ characteristic ability to maintain a harvest index of 50 to 55%
Hodgen and Schepers, 2007Hodgen and Schepers, 2007• The results of this study indicate that producers need to
be aware of agronomic management practices that lead to uneven emergence can result in lower yield potential as 5% of yield was lost by just one day of delayed emergence.
• Results from this study indicate the early emerging corn plants produce more kernels per plant and are thus higher yielding and more competitive than late emerging plants.
• The economic impact from even small differences, such as four days, in uniformity of emergence between corn plants can contribute to lower yields of late emerging plants. The loss in yield would then lower the potential return to investment of not only seed expenditures but potential response to applied N fertilizer.
Corn grain yield as a function of delayed emergence, NE
y = -1154x + 18080
R2 = 0.9436
2000400060008000
100001200014000
4 5 6 7 8 9 10 11 12 13 14
Delayed emergence
co
rn y
ield
, kg
/ha
Corn Grain yield as a function of Delayed emergence, OK
y = -121.66x + 9826
R2 = 0.9653
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0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Delayed emergence
Yie
ld, k
g/h
a
Hodgen, PhD Dissertation
Real-Time Use of Mesonet Weather Data for Refined
GreenSeeker Sensor Based N
Recommendations in Winter Wheat
Real-Time Use of Mesonet Weather Data for Refined
GreenSeeker Sensor Based N
Recommendations in Winter Wheat
On-Line N RecommendationsOn-Line N Recommendations
• 21 algorithms on-line, Sensor Based Nitrogen Rate Calculator (SBNRC) that are being used in Oklahoma, many Mid-Western States, Australia, India, Mexico, China, Argentina, and Canada. Algorithms now included on our OSU site encumber winter wheat, spring wheat, corn, canola, bermudagrass, sorghum, rice, and cotton (http://www.soiltesting.okstate.edu/SBNRC/SBNRC.php).
Figure 1. Digitized Mesonet maps of fractional water index for November 27, 2005 (left) and November 27, 2006 (right), at the 24 inch depth, Oklahoma (brown-dry, green-wet). Campbell Scientific, 229-L
Average Response to Applied NAverage Response to Applied N
y = 0.0295x + 4.2261
R2 = 0.1423
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2.00
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0 50 100 150 200 250
Pre plant N, kg/ha
Yie
ld,
Mg
/ha
Cubic
Mg/ha kg/ha
NDVI FP NDVI N Rich Sum GDD CoefA CoefB Pred. Yield Fert Cost Grain Price NUE
0.5 0.71 750 4.893525 0.988125 8.02029659 8020.29659 0.5 4.5 0.372
CoefA CoefA = 6E-08x3 - 0.0002x2 + 0.1122x - 18.731
CoefB CoefB = -5E-08x3 + 0.0001x2 - 0.1183x + 31.78
YP0 = (CoefA * EXP (CoefB * NDVI))
x = cummulative GDD
40% NUE
Olga 12.6 kg grain/ kg N applied topdress 0.828 lb N/bu 27.05 lb loss for 1.0 lb N rate error
OFIT 29.5 kg grain/ kg N applied preplant
Varvel 24.2 kg grain/ kg N applied preplant OSU data UNL data
Yield Loss Yield Loss
due to YP0 due to YP0
Rate Reduction error error
% Error YP0 YPN N Fert. Rec Due to Error bu/ac bu/ac N Fert. Expense Grain Revenue Gross Profit
0.0 127.9 230.1 119.3 0.0 59.6 1035.4 975.8
5.0 121.5 218.6 113.3 6.0 1.3 2.7 56.6 1023.4 966.7
10.0 115.1 207.1 107.3 11.9 2.7 5.4 53.7 1011.3 957.7
15.0 108.7 195.6 101.4 17.9 4.0 8.0 50.7 999.3 948.6
20.0 102.3 184.1 95.4 23.9 5.4 10.7 47.7 987.2 939.5
25.0 95.9 172.6 89.4 29.8 6.7 13.4 44.7 975.2 930.5
30.0 89.5 161.1 83.5 35.8 8.0 16.1 41.7 963.1 921.4
35.0 83.1 149.6 77.5 41.7 9.4 18.7 38.8 951.1 912.3
40.0 76.7 138.1 71.6 47.7 10.7 21.4 35.8 939.0 903.3
45.0 70.3 126.6 65.6 53.7 12.1 24.1 32.8 927.0 894.2
50.0 63.9 115.0 59.6 59.6 13.4 26.8 29.8 914.9 885.1