Nitrogen Use Efficiency, Nitrogen Fertilizers, NUE, Nitrogen and the Environment The Case for By Plant N Management
 (mid-season prediction of grain yield)
Causes of Plant to Plant Variability in Yield within Corn Production Systems By plant corn nitrogen management for improved nitrogen use efficiency By-Plant Yield Prediction in Corn Production Systems
 
The Case for By-Plant Management

1. By plant prediction of corn (Zea mays L.) grain yield using height and stalk diameter. Commun. Soil Sci. Plant Anal.  46:564-575.
2. By-Plant Prediction of Corn Forage and Grain Yield Using NDVI and Plant Height at Various Growth Stage, Freeman et al. (2004)

3. Uptake of Point Source Depleted 15N Fertilizer by Neighboring Corn Plants. Agron. J. 101:99-105.
By Plant and Large-Scale Corn Yield Prediction
CV algorithm tested for variable N application in Winter Wheat

Estimating Corn Yield Losses from Uneven Plant Spacing (Carlson, Doerge, Clay)

Plant to Plant Variability in Corn Production (Agron. J. 97:1603-1611) (pdf)
By-plant variability in corn grain yield (46 transects)

By-Plant N Management and Delayed Emergence Trials

Use of Fixed Distances or Actual Distances to Compute By-Plant Corn Grain Yields, What is the Difference?

Causes of By-Plant Variability in Corn Production Systems

 Spatial Variability of N, What is the Scale?

What are the Errors in Predicting Yield on a By-Plant Basis?

Nitrogen Uptake in Wheat and Corn


 
OSU Corn Research Page  (has excavated plants in place) Foliar UAN, Mexico 2002
  • Average USA corn yield: 153.9 bu/ac

  • Corn Acres Planted: 85.9 million acres

  • Corn Production USA: 12.1 billion bushels

Wheat Feekes Growth Stages
NVDI Sensor Reading

Corn yield prediction from NDVI sensor readings collected at V8 from locations in Mexico, Nebraska, Iowa, and Oklahoma where INSEY (in-season estimated yield) was NDVI divided by the cumulative growing degree days from planting to sensing.

 
Corn yield prediction, Ohio, Dr. Robert Mullen
Corn yield prediction equation developed by Dr. Robert Mullen using GreenSeeker NDVI values collected between V6 and V10 divided by the cumulative growing degree days from planting to sensing. 

The above graph shows results over 2 years (6 total sites in Oklahoma) where corn forage N uptake can be predicted from growth stages ranging from V8 to V10.  However, it should be noted that this was from by-plant data (NDVI and N uptake determined by-plant).

Relationship between cotton lint yield and INSEY (NDVI divided by cumulative GDD)

Mean: 9496.17 kg/ha
Standard Deviation: 3737.60 kg/ha

Mean 9983.29 kg/ha
Standard Deviation: 4132.39

Lake Carl Blackwell, Oklahoma.  Variability in by-plant corn yields over 15 m of row.


Shelton, NE, MSEA Site, USDA-ARS 2004.  Work by Paul Hodgen, Kent Martin, and Kyle Freeman has shown that SPAD readings taken "by-plant" at V16 were highly correlated with final "by-plant" grain yields. This relationship would not have been observed unless the by-plant resolution had been used.

 
Reproducibility of NDVI readings over 16m using an on-board shaft encoder, with 50 corn plants sensed at the 7-leaf growth stage on May 23, 2003, Perkins, OK.
Average NDVI (by-plant) determined by collecting sensor readings from the sum of 1/2 the distance left and right to its neighboring plants. Similarly, by-plant yields were determined from the from the exact same area for which NDVI measurements were captured.

Do corn roots overlap when plants are more than 7 inches apart?  When corn plants were excavated from a corn field to a depth of 2 feet, few rooting cylinders overlapped, unless plants were less than 7 inches apart.  Over 70% of the root mass was found to exist within a 6 inch diameter of the stalk, further supporting by-plant variable N application in corn.


After excavation and complete root washing, corn plants were placed in the exact same location as from the slide above.  Root systems from these plants were then thoroughly evaluated.  Unless the plants were within 6 inches of each other, the 70% by-plant root mass (exists within a 6 inch radius of the stalk) did not overlap with bordering plants.  Thus treatment of each plant or every 2 plants within 6 inches makes a lot of sense in corn since N can be accurately placed within the 70% root mass. 

By Plant Corn Yield Prediction
The New Greenseekers for corn

 
 
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