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Leaf Color Chart: A Cost-Effective Tool for Nitrogen Management

The Issue

Precise application of nitrogen (N) fertilizer based on plant need and location in the field greatly improves fertilizer use efficiency in rice growing. This maintains yield while helping to reduce nitrogen runoff into surface and ground water. Moreover, higher energy costs have increased fertilizer prices. One way to improve the economics of rice production is to estimate tissue N status at critical points in the plant's life cycle. To do this effectively, a rice grower must evaluate large acreages and make management decisions quickly.

What Has ANR Done?

A UCCE farm advisor has developed an easy-to-use, inexpensive and accurate tool for determining nitrogen status in rice plants--the Leaf Color Chart. The LCC is a series of panels with colors based on the wavelength characteristics of rice leaves. The spectral data were transferred into color-matching computer software and pigment formulations were developed utilizing light and heat-stable colorants.

The color panels are constructed of acrylic plastic that withstands high temperatures. Ribbing was added to the individual color panels to reduce glare. The resulting color chart is durable and ready for use in the field.

On-farm studies have demonstrated that the LCC accurately predicts leaf N levels in major California rice varieties at growth stages when N status is most critical for high yields. UCCE maintains a list of growers using the LCC so new calibration data can be sent via mail.

The Payoff

Real-time nitrogen management rice improves the bottom line

In the Sacramento Valley, over 300 Leaf Color Charts are in use as it has become an integral part of the fertility management program for farm managers and private consultants. The LCC evaluates nitrogen status of a rice crop cost-effectively, avoiding leaf sampling, laboratory analysis costs and time delays in receiving the results.

(UC's Office of Technology Transfer has filed for a patent on the LCC concept and the technological innovations used to produce it.)


Supporting Unit: Butte County

Randall Mutters, Butte County UCCE Farm Advisor,
2279 B Del Oro Avenue, Oroville, CA 95965
(530)538-7201 rgmutters@ucdavis.edu