ARS | Publication request: TIME OF DAY AND CORN LEAF WETNESS EFFECTS ON ACTIVE SENSOR READINGS

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 1, 2004
Publication Date: November 1, 2004
Citation: Solari, F., Hodgen, P., Shanahan, J.F., Schepers, J.S. 2004. Time of day and corn leaf wetness effects on active sensor readings. Agronomy Abstracts #4253.

Technical Abstract: Our long-term research goal is to develop practical N application systems that use on-the-go remote sensing as a means to assess crop N status and only apply N where needed at times when the crop can most efficiently utilize N. Our preliminary testing of two active sensor systems has shown considerable promise for rapid and accurate assessment of canopy N status. In this work two active sensor systems were evaluated for their ability to perform under a range of light and leaf wetness conditions, as might be encountered during field operation of sensors under center-pivot irrigation or throughout the course of a day. Sensor measurements were collected over two different backgrounds in the laboratory under total darkness and halogen-illuminated conditions as well as in the field under variable sunlight conditions to determine if illumination affected sensor readings. Results showed that, in general, variable light conditions did not affect sensor readings. To determine if leaf wetness affected sensor readings, sensors were positioned over the canopy on a rail with a motorized shaft to systematically move the sensor over the canopy, while acquiring readings before, during, and after watering. Leaf wetness did not affect sensor readings. Results are discussed in relation to potential use of these sensors and their limitations.