UC Delivers

App helps coastal farmers better manage nitrogen fertilizer and water

The Issue

Vegetable crops produced on California’s central coast need sufficient moisture and nitrogen in the soil to generate optimum commercial yields and quality. Ground water from wells is used for watering crops and is also the primary drinking water source for coastal communities. After many years of over-irrigation and high nitrogen fertilizer application rates, intended to produce good yields for these commodities, many rural wells now show nitrate concentrations in excess of safe drinking water standards. In addition, over-pumping of agricultural wells has actually pulled seawater into some coastal aquifers, contaminating many freshwater wells with salt water. Recently adopted California water laws will soon require farmers to reduce pumping to levels low enough to stop long-term depletion of ground water supplies.

What Has ANR Done?

Two UC ANR tools have great potential to help farmers conserve water and make better use of nitrogen fertilizer while maintaining crop productivity and quality: weather-based irrigation scheduling and the soil nitrate quick test. The soil nitrate quick test is an in-field test that lets growers quickly determine whether their soil has adequate nitrogen. Weather-based irrigation scheduling uses weather station data to determine actual crop water needs. Both tools use information about the specific crops to determine how much fertilizer and water each will need from the soil. CropManage (ucanr.edu/cropmanage) is an online application that makes both tools easy and accessible for growers to use. A grower can access the app via smart phone, tablet, or desktop computer and quickly determine the crops’ fertilizer needs based on in-field soil nitrogen tests and research-based guidelines for crop nitrogen use. The app also estimates crop water needs using weather data from the California Irrigation Management Information System together with crop development models. Growers can use CropManage to track and manage water and nitrogen fertilizer applications for each of their fields.

The Payoff

CropManage helps growers reduce nitrogen and water use by more than 30%

Commercial-scale trials in lettuce demonstrated that growers using CropManage can reduce nitrogen and water without compromising quality or yield. The nitrogen rate recommended by CropManage generated yields similar to those of the growers’ standard practice, but with an average reduction of 32% in nitrogen fertilizer. Commercial-scale CropManage trials with broccoli used 48% less water than is used for conventional plantings, with no reductions in yield or crop quality.

Since the trials concluded, several major vegetable growing operations in the Salinas Valley have begun using CropManage to help make their water and fertilizer use more efficient. One lettuce grower using CropManage recommendations brought nitrogen applications down by more than 40%. As more commodities and features are added to the online tool, we expect increasing numbers of farmers to start using CropManage to reduce their costs, and improve environmental conditions.

Clientele Testimonial

"The partnership with UC in trialing and implementing CropManage is helping our company meet our sustainability goals, and helping our growers save on production costs." - Ted J. Mills, VP Ag Operations Fresh Express

Contact

Supporting Unit:

Michael Cahn
mdcahn@ucanr.edu