|Lobdell, B - UNIV OF IL|
Submitted to: Intnl Conference On Geospatial Information In Agriculture And Forestry
Publication Type: Proceedings
Publication Acceptance Date: November 7, 2001
Publication Date: N/A
Interpretive Summary: Plant population has a significant effect on corn yield potential and with the exception of climatic conditions, can be the predominant factor limiting crop yield. In precision agriculture, producers need a map of plant population for a field, so that relationships between population and other variables such as soil type, can be used in optimizing application of finputs. The cost and time required for the intensive sampling needed, using hand sampling techniques, make implementation impractical. On-the-go population sensors might be used to collect the desired data. Commercially available photoelectric sensors were incorporated into a population sensor system and mounted on a combine for field testing. Air-jets were added to blow leaves and debris from the sensor area, and different levels of air velocity were tested. Software filtering techniques were developed to improve plant diameter, spacing, and population estimation. The addition of the air-jets decreased false counts and resulted in more accurate estimates of plant population. This technology will allow corn producers to set target nitrogen (N) fertilizer application rates across a field to increase N-use efficiency by the plants and decrease offsite discharge of N to streams and rivers for improved downstream water quality. Results will be useful to extension personnel, fertilizer dealers, and the farming community.
Technical Abstract: Site-specific estimation of corn population at harvest makes it possible to evaluate problem areas in a field where yield was decreased due to plants not emerging or dying during the growing season. Variable rate planting systems could also be evaluated. Supplementary information, such as plant diameter and plant spacing uniformity, might also be obtained while collecting population data. A four-row photoelectric corn population sensor system was developed and mounted on a combine for field testing. High-velocity air jets were used to blow leaves and weeds away from the light beam of the optical sensors to reduce the number of false counts. Data were collected on test plots of approximately 200 plants each. Three replications of fifteen different treatments of data were included in a split-block statistical design. The fifteen treatments were combinations of three combine travel speeds (4, 5, and 6 km/h) and five different air treatments. Data were post-processed to compare with manually collected plant diameters and spacings, and filtering techniques were developed to improve diameter, spacing, and population estimation. The higher air speed levels decreased false optical counts caused by leaves and weeds resulting in more accurate estimates of plant population.