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United States Department of Agriculture

Agricultural Research Service

Title: Estimating Crop Coefficients with Crop Canopy Size

Author
item Trout, Thomas

Submitted to: Acta Horticulture Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: May 30, 2006
Publication Date: August 27, 2006
Citation: Trout, T.J. 2006. Estimating crop coefficients with crop canopy size. Acta Horticulture Proceedings. Mildura, Australia. August, 2006.

Technical Abstract: Planting time, plant density, variety, and cultural practices vary widely for horticultural crops. It is difficult to estimate a basal crop coefficient that can incorporate these variations. Canopy cover, as an indicator of intercepted sunlight, is related to crop water use. We used a weighing lysimeter to measure daily crop water use and a multi-spectral camera to measure canopy cover for two vegetable crops – head lettuce and bell pepper, and related canopy cover to basal crop coefficient. The ratio of crop coefficient to canopy cover declined from about 4 with small canopy cover (0.1) to about 1.3 for a mature crop with canopy cover of 0.9. The relationship was similar for these two crops. Because light interception other than at mid-day will depend on the canopy structure, adjustment may be needed for canopy structure. A generalized canopy cover:basal crop coefficient relationship would allow weather-based irrigation scheduling for a wide range of horticultural crops based on canopy measurements, and possibly based on remotely-sensed vegetation indices.

Last Modified: 7/24/2014
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