Advisors, tools help farms with water-quality rules
By Bob Johnson A number of interests are helping growers satisfy challenges of meeting stricter water-quality regulations and completing paperwork required by California regulators. University of California Cooperative Extension researchers joined the California Department of Food and Agriculture to create a new Nitrogen and
Irrigation Initiative, which aims to ad- vance research and education on irriga- tion and fertilizer decisions in the Central Coast and San Joaquin Valley. “We will be offering information on when to irrigate,” said Aparna Gazula, a UCCE small farms advisor in Santa Clara, Santa Cruz and San Benito counties. “We will also help measure how much water is being applied, evaluate irrigation
distribution and pressure uniformity.” Gazula made her remarks as research- ers discussed the challenge of meeting strict water-quality standards during an irrigation and nutrient management meeting sponsored by UCCE last month in Salinas. Under regulations adopted by the Central Coast Regional Water Quality Control Board, growers must reduce
nitrogen applications to a maximum of 50 pounds of nitrogen per acre after crop removal to safeguard groundwater by late 2051. Central Coast growers must submit ap- plied nitrogen reports by March 31. Central Coast Water Quality Preservation Inc. is a farmer-direct- ed nonprofit that assists Central Coast farmers in complying with regulations. In addition, UCCE advisors hold on- farm training workshops to help irriga- tors learn how to use soil-quick tests on nitrogen already available to the crop in the root zone. CropManage, a free, web-based soft- ware created by UCCE, automatically up- dates water requirements for each of the growers’ fields using evapotranspiration data from regional weather stations and measurements of applied water derived from in-field flow meters. With the software, growers can imple- ment better fertilizer and water manage- ment practices while achieving water quality targets for ground and surface water supplies on the Central Coast. Growers may establish a CropManage account for each field or ranch they want in the program. They enter crop informa- tion, time of planting, amount of irriga- tion and fertilizer applied, and results of well-water and soil-quick tests on nitro- gen available to the crop. CropManage began in 2011 with cal- culations for growing lettuce and the soft- ware has grown to include 15 different vegetable crops, including fennel, bok choy and Napa cabbage. “CropManage enables growers to ac- count for the nitrogen fertilizer contri- bution from background levels of nitrate in the irrigation water and maintain re- cords of water and fertilizer applications for regulatory compliance,” UCCE farm advisor emeritus Richard Smith and UC researcher Michael Cahn wrote in a re- port in Agriculture Water Management. In addition, farmers can access National Aeronautics and Space Administration software that provides crop water-use information. GEO- CropSim, a satelite-based crop modeling techology created in partnership with the U. S. Department of Agriculture, helps monitor crop production and analyze water consumption. To measure evapotranspiration, NASA continues to improve its satellite-based OpenET data program for crop water use, said Lee Johnson, who works for NASA and teaches at California State University, Monterey Bay. “You can access data for part of a field, an entire field or several fields in a ranch,” he said. The USDA Natural Resources Conservation Service also provides technical and financial assistance to help growers implement conservation prac- tices that improve water quality. (Bob Johnson is a reporter in Monterey County. He may be contacted at bjohn11135@gmail.com.)
12 Ag Alert March 13, 2024
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