Test and improve your farm’s irrigation efficiency

By John L. Varela, District 1 representative

How much of your irrigation is getting where it needs to go at the rate it needs to get there?

To help owners and managers of commercial agricultural crops or nurseries answer this question, the Santa Clara Valley Water District offers the Mobile Irrigation Lab Program.

Better irrigation efficiency can lead to improved crop yield and quality. This free program, which will start back up in spring, allows owners and managers to evaluate the efficiency of their irrigation systems – no matter what type – and includes recommendations to improve it.

How does it work?

First, the owner or manager of the farm or nursery has a phone or onsite consultation with an irrigation specialist to collect information related to crop production and irrigation practices. Then they set a date to test a field or section of the irrigated area.

During the efficiency evaluation, the irrigation specialist collects on-farm data to measure how evenly the irrigation system delivers water to the plants. That measurement is called the “distribution uniformity,” and it can vary drastically between farms and even between irrigation methods within the same farm. Comparing distribution uniformity of a farm or nursery to the performance standards set by the irrigation industry and the American Society of Agricultural Engineers can help evaluate the system design and operation, and to manage and improve its performance.

Recommendations for improving irrigation efficiency are made based on the distribution uniformity, and all the recipients of the on-farm irrigation evaluation are eligible for re-testing after implementing one or more recommendations.

The field evaluation can take anywhere from 2-8 hours or more depending on the size of the farm. It also includes a Soil Nitrate Quick Test to screen for significant levels of nitrogen concentration in the irrigation water. The growers are taught how to use this method on their own and are also shown the protocol for testing nitrogen concentration in the soil profile. Growers are given a simple test kit for performing these tests on their own for ongoing monitoring.

Once the evaluation is done, the irrigation specialist analyzes the data and compiles it into a written report that includes soil information, actual field pressure map, pictures, distribution uniformity determination, water application rate, nitrogen awareness, system recommendations, irrigation scheduling information, irrigation efficiency information, and the farm-specific field data collected.

Reports are generally delivered and reviewed in person with the farm owner or manager and in some cases with the irrigation foreman or irrigator for the small farms. Participants are also given an option to review and discuss current irrigation scheduling practices to make improvements for the coming year. These improvements may come in the form of record keeping with graphic soil moisture status, soil moisture sensor usage, and/or the use of evapotranspiration information.

Other services performed through the current Mobile Irrigation Lab program include post crop water and system analysis as requested, optional flow meter installation through a collaboration with the Resource Conservation District of Santa Cruz, irrigation scheduling and efficiency recommendations, and irrigation training classes in partnership with the resource Conservation District of Monterey County covering basic and advanced irrigation concepts and practices through two days of classes. These classes are for Spanish-speaking irrigators, and they conclude with individual certification by written examination.

To sign up for the free Mobile Irrigation Lab Program this spring, call (408) 630-2951.

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