Vegetable growers find over-irrigating leaves profit, environment “all wet”

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

Editor’s note
: This article is reprinted from Issue>Action>Impact Vol. 1, No.3, Summer 2007.

When MSU researchers decided to evaluate grower irrigation practices in southwestern Michigan, they discovered that some growers were running their drip irrigation systems upwards of eight hours per day. Producers were employing this practice as insurance that crops were receiving enough moisture, however costly nutrients were being washed away – not an efficient use of water or nutrients.

Realizing the importance of helping growers identify the economic and environmental consequences of their irrigation practices, researchers secured funding from Project GREEEN to develop a system for measuring soil moisture. After installing a series of monitoring tubes in test fields, soil moisture levels were measured by putting a probe attached to a monitor and data logger into the tube. Information from the data logger is downloaded into a computer, which generates a printout graphing how the past week’s irrigation application has affected the soil moisture level – too much, not enough or just right.

Upwards of 50 sites on 15 vegetable operations were studied in the first year of the two-year project. Data indicated that some growers irrigated too much too early in the season – there were times when moisture levels were off the chart topping more than 100 percent field capacity. Researchers also found that regardless of the grower or soil type examined moisture levels dropped off significantly at harvest time when irrigation took a back seat.

“Harvest time is probably the most important time for maintaining adequate moisture levels because this is when it contributes most to fruit size,” says Ron Goldy, MSU Extension vegetable educator. “By and large we found that the soil was drying out when water was the most critical.”

Over the course of the two-year project, study results were presented to growers at winter meetings. When funding for a third year of research was not guaranteed, growers stepped up and volunteered to pay for the program. Four growers signed up to continue; last year there were five growers and this year there are seven. The program has expanded beyond vegetable crops and now includes apples and blueberries.

Goldy believes the reason growers embraced the system was because it directly involved the producers on their own land.

“The project wasn’t done on campus, in the laboratory or at a research station,” he says. “It appealed to them because it was conducted right on the farm in their own fields.”

“Before this, growers have never been able to readily see or measure the moisture level in the field,” Goldy says. “We’ve been able to show the water level where the plant roots are working in and whether it’s too wet or too dry.”

Goldy says the reports help producers know how long to operate their irrigation systems each day based on weather and plant stage. As an example, he cites that one grower has been able to reduce his water use by 50 percent since starting to use the system.

“It helps when growers have an opportunity to apply the technology on their own farm,” Goldy says. “They tell us that this helps them understand the usefulness of the system and that it’s not that expensive, especially when they pencil out how much money they save by cutting irrigation use. This is one additional piece of information to help growers make their final decision.”

Future plans include continuing to expand the irrigation program to include more commodities.

“Growers don’t realize what they have until they have it,” Goldy adds. “Growers have recommended the system to others so they must find it valuable. Word of mouth is the most effective sales tool.”

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