Submitted to: International Conference on Precision Agriculture Abstracts & Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: February 23, 2006
Publication Date: July 23, 2006
Citation: Bausch, W.C. 2006. Comparison of active and passive optical sensors for assessment of plant nitrogen. International Conference on Precision Agriculture Abstracts & Proceedings. Conference Abstract., pp 117; Minneapolis MN July 23-26, 2006. Technical Abstract: Nitrogen (N) fertilizer has received attention for a long time as a potential source of ground water pollution. Considerable research has been conducted to investigate use of remote sensing for assessing plant N status to improve N use efficiency. Most of these studies have used passive type sensors which require sunlight. Unfortunately, clouds hinder their performance. Active type sensors provide their own illumination which means they can be used to take measurements anytime of day under all possible sky conditions. Disadvantages of these sensors are their small field of view and the close distances required between the sensor and target because of power constraints. A view angle study was conducted to determine sensor orientation with respect to the plant canopy for corn and potatoes. In addition to the traditional nadir view, various off-nadir view angles from 15' to 75' were investigated. This was done several times during the growing season for extended periods throughout a given day. The active sensor was also compared to a passive system to determine if differences existed between sensor response to various levels of leaf N content in irrigated corn. Both sensor systems were also used in a commercial corn field to map N sufficiency to determine when and where in the field the corn crop required additional application of N fertilizer during the growing season. Results from these studies will be presented to show differences between the two systems.