Deep Root Irrigation (DRI) Demonstration
Summer 2019 Demonstration Project: Tomatoes
Objective
Demonstrate the use of DRI to reduce surface evaporation of water and the incidence of weed germination and growth
Summary of Results
In the raised bed in which DRI lines were installed, the transplanted tomatoes were noticeably and obviously greener, larger, and had more fruit. In the raised bed in which flood irrigation was used, besides the plants being smaller had many more weeds present.
Project
Raised beds were used with transplanted tomatoes to demonstrate the installation and use of DRI lines. This was not a controlled research, but strictly a classroom demonstration showing difference between a subsurface drip and surface application of water.
DRI Agrees to:
- Provide DRI devices for use in demonstration and student use;
- Assist in installation of devices in raised beds;
- Participate in video recording of installation for student use;
Coalinga CollegeAgree to:
- Discuss use of DRI devices as a topic within various classes;
- Offer students opportunity for internship with DRI as an installer;
- Use DRI devices in the establishment of pistachios saplings in Orchard Production class.
Description:
Tomatoes were established in two beds as a part of a Lab Exercise for Introduction to Plant Science class in which students were responsible for evaluating planting area, creating an appropriate planting bed and planting a transplant. Don Lewis and Mark Giangiorgi, DRI representatives installed: three 12” DRI-12 devices between two plants each; three 6” DRI-6 between two plants each; and two 3” DRI-3 on individual plants.
Based on water pressure, flow rate, and the pressure compensating emitters on the dripline, the amount of water provided for a 15 minute period was calculated. For each 15 minutes in which the DRI bed was irrigated, an equal amount of water was surface applied evenly to the tomatoes in the other (non-DRI) bed.
Anecdotal Results:
Though no quantifiable data was collected as a classroom demonstration, the results were very obvious.
The majority of tomato plants in the DRI bed were large and had a dense canopy. The number of flowers and developing fruit was higher than the plants in the non-DRI bed. The size and condition of the plants were easily due to water stress.
One plant of a pair that should have been receiving water from one of the 12” DRI devices was smaller and showed symptoms of a lack of water (the other plant was in good condition). It was surmised that root development toward the DRI device did not occur, though it was not determined to be caused by soil patterns within the raised bed or placement of the device.
There were an obvious lack of weeds in the DRI bed compared to the non-DRI bed. The only weeds that grew were at two locations where water had percolated upward to the surface. In the non-DRI bed weed removal was a daily task.
Summary
The project did not continue after classes ended on May 15. Though tomatoes plants were not harvested or quantitative data collected several conclusions could be made from this project.
- Subsurface irrigation is a more efficient method of water placement than surface. Even though a point is made that products should not claim to save water, the point should be made that plants need a set amount of water and how that water is delivered to the plant can result in savings.
- Subsurface irrigation does discourage weed development. It may not eliminate all weeds but the germination of seeds on or close to the surface is clearly hindered.
- DRI devices worked effectively in delivering water subsurface. Installation of the 3” and 6” devices were extremely easy; installation of the 12” was more difficult (though we were using them in a vegetable crop and they are designed more appropriately for orchard use).