BY-PLANT RESOLUTION
Feb 23, 2016
BY-PLANT RESOLUTION
1992, At What resolution are there real biological differences
IOWA OKLAHOMA
Plant-to-plant variation, avg. 45 bu/acNebraska, Iowa, Virginia, Oklahoma, Argentina, Mexico, Ohio (46 transects)
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Yiel
d (k
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Distance (cm)
Grain Yield Over Linear Distance (Shelton, NE)158 ± 67
Holdrege silt loam, Minden, NE
Mean Yield vs Std. Dev.
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Mean Yield, kg/ha
Std.
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. Yie
ld, k
g/ha
OklahomaIowaNebraskaMexicoArgentinaOhioVirginia
StdDev =920.71 +5.16E-5 Yld2 - 2.7 E-9 Yld3
R2 = 0.498
Average corn grain yield plotted against the standard deviation from by-plant yield over 46 transects in Argentina, Mexico, Iowa, Nebraska, Ohio, Virginia, and Oklahoma.
318 bu/ac
Paul Hodgen, Univ. Nebraska, Dissertation AA13271926, Jan 1, 2007
Target plant acquired over 70% of the total depleted 15N fertilizer that was taken up
data revealed an individual corn plant acquires most of its N from within a radius of less than 0.5 m.
Plants lose yield potential by emerging as little as three days after their neighbors.
Large doses of N fertilizer could not increase the yield of late emerging corn plants.
Sensors to detect each plant
• GreenSeeker Sensor was mounted on a bicycle• Shaft encoder was used to assign distance to each sensor reading• Readings were taken once per centimeter
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2/)(2/)( 2
1
2
1
pqpq
pq
pqpq
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pq
adj
HtHtHt
HtHtHt
HtC
Grain Yield = 15083 * GYest + 3315R2 =0.48
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Gra
in Y
ield
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EFAW, OK (2004)
LCB, OK (2004)
Hennessey, OK (2004)
EFAW, OK (2005)
LCB, OK (2005)
New by-plant yield prediction methods focus on a totally different approach
Can you recognize by-row differences in N response?
If the answer is yes, then the minimum resolution at which “precision agriculture” should operate is 30 inches (front/back, left/right)
Variable Rate Technology Treat Temporal and Spatial Variability Wheat, 0.4m2
Corn, by plant
Causes for Delayed and uneven emergence
•variable depth of planting •double seed drops •wheel compaction •seed geometry within the furrow •surface crusting •random soil clods •soil texture differences •variable distance between seeds •variable soil compaction around the
seed •insect damage •moisture availability •variable surface residue •variable seed furrow closure •volunteer
early season root pruning (disease, insect)
The impact of uneven stands takes place prior to the time that irrigation is employed whether using surface/furrow or center pivot systems.
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bu/a
c
Distance, ft
Variation in Wheat Yields, 3' increments(Lake Carl Blackwell)
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bu/a
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Distance in Feet
Variation in Wheat Yields, 3' increments(Manchester)
37 ± 9 bu/ac
34 ± 5.3 bu/ac
Summary Farmer fields in the US, Argentina, and Mexico
showed that plant-to-plant variation in corn grain yield averaged 2765 kg ha-1 or 44.1 bu ac-
1 (Martin et al., 2005). Current methods can predict by-plant yields Plant to plant variability in yield exceeds the
magnitude encountered for other agronomic variables
Adjusting multiple inputs by-plant is possible today