By-Plant N By-Plant N ManagementManagement

Oklahoma State University

Scale

Ames, IA

Ames, IA

Stillwater, OK

By-Plant N ManagementBy-Plant N Management

Paul Hodgen, Jim Schepers, 15N

60% of by-plant N accounted for in individual plants

Ames, IowaAmes, Iowa

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Distance (cm)

Gra

in Y

ield

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ha-1

)

Shelton, NE

Ames, IAAmes, IA

Agron. J. 97:1603-1611Agron. J. 97:1603-1611

At the sites with the highest average corn grain yield (11478 and 14383 kg ha-1, Parana Argentina, and Phillips, NE), average plant-to-plant variation in yield was 4211 kg ha-1 (67 bu ac-1) and 2926 kg/ha (47 bu ac-1), respectively.  As average grain yields increased, so too did the standard deviation of the yields obtained within each row.  This clearly indicates that by-plant variability can be expected in high and low yielding environments.  Furthermore, the yield range (maximum corn grain yield minus the minimum corn grain yield per row) was found to increase with increasing yield level.  This work shows that regardless of yield level, plant-to-plant variability in corn grain yield can be expected and averaged more than 2765 kg ha-1 over sites and years.

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)

5-Plant Sequence5-Plant Sequence

pq-2 pq-1 pq Pq+1 Pq+2

2/)( 2

1

pqpq

pq

HtHt

Ht

2/)( 2

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pqpq

pq

HtHt

Ht

2/

2/)(2/)( 2

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2

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pqpq

pq

pqpq

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pq

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Ht

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Ht

Ht

Cadj of the Plant in Question

FormulaFormula INSEYC D

GY adjest

Grain Yield = 15661 * GYest + 3367.2R2 =0.48

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EFAW, OK (2004)

LCB, OK (2004)

Hennessey, OK (2004)

EFAW, OK (2005)

LCB, OK (2005)

Treatment StructureTreatment StructureTrt Pre-plant

kg ha-1 Top-dress (V8-V10)

kg ha-1

Method

1 45 22 By plant at base

2 45 22 By row at base

3 45 22 DSB at center

4 45 45 By plant at base

5 45 45 By row at base

6 45 45 DSB at center

7 45 90 By plant at base

8 45 90 By row at base

9 45 90 DSB at center

10 45 180 By plant at base

11 45 180 By row at base

12 45 180 DSB at center

13 0 0 -

14 45 0 Broadcast

15 225 0 Broadcast

Methods of placementMethods of placement

By-plant By-row

Between rows

LCB 2007

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0 67 90 135 225

N rate, kg N ha -1

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in y

ield

, M

g h

a

-1

Check

Each plant

Each row

Between rows

SED = 1.15

Haskell 2005

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0 67 90 135 225

N rate, kg N ha-1

Gra

in y

ield

, M

g h

a-1

Check

Each plant

Each row

Between rows

SED = 0.55

•By-plant fertilization method had slightly higher yields in five out of six site-years, especially at the low N rate. •In five of six site years the middle N rates of 67 and 90 kg N ha-1 showed grain yields as high as or higher than the 135 and 225 kg N ha-1 N rates.

ResultsResults