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ARS Home » Midwest Area » Columbia, Missouri » Cropping Systems and Water Quality Research » Research » Publications at this Location » Publication #125549
Title: SENSING CORN POPULATION-ANOTHER VARIABLE IN THE YIELD EQUATION

Author
item Hummel, John
item LOBDELL, B - UNIV OF IL
item Sudduth, Kenneth - Ken
item BIRRELL, STUART - IA STATE UNIV

Submitted to: InfoAg Conference
Publication Type: Proceedings
Publication Acceptance Date: 8/31/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Plant population has a significant effect on yield potential and, with the exception of climatic conditions, can be the predominant factor limiting crop yields. Sensor-derived maps of plant population can be useful for interpreting the effect of other limiting factors on yield and can provide important information for developing site-specific management plans. We designed and fabricated a mechanical sensor that counted corn plants as they entered the gathering chains of a combine header. When compared to hand counts obtained at harvest, the sensors tended to slightly under- estimate actual population. Errors were minimized when the combine header was operated close to the ground surface and at speeds no greater than 4.5 mph. Sensor evaluation in corn seeded at various rates revealed an increasing underestimation error with increasing population. After compensation was applied, sensed population was an excellent estimator of actual, hand-counted population (r2 = 0.93, zero mean error). Standard errors of population estimates were 802 plants/ac at feed rates below 9 plants/s and 1700 plants/ac at feed rates above 9 plants/s. A photoelectric sensor, capable of estimating plant diameter and plant spacing as well as population, was developed and field tested. An air-jet system was fitted onto a combine header to move corn leaves and other debris away from the sensor area. Data were collected at harvest with the sensor and post- processed to compare with manually collected plant diameters and spacings. Filtering techniques were developed to improve diameter, spacing, and population estimation. Higher air speed levels decreased false optical counts caused by leaves and weeds and produced more accurate estimates of plant population.