Del. Research Aims to Make Irrigation a More Exact Science

12/8/2012 7:00 AM
By Michael Short Delaware Correspondent

GEORGETOWN, Del. — What if a farmer knew exactly how much irrigation his crop needed?

No more feeling the soil or looking at whether the corn has started to look spiky and dry.

What if educated guesses could be replaced with a precise measurement of how much moisture is still within the soil?

A University of Delaware project will place sensors in 20 fields of either corn or soybeans beginning next year. Over a three-year period, moisture sensors will be placed in a total of 60 fields owned by 60 farmers.

It's a small project intended to help turn the inexact science of irrigation into something with real, hard data that will tell farmers exactly how much moisture is needed.

Making irrigation more efficient can help to maximize crop yields, reduce unnecessary water loss and protect the environment by preventing unnecessary runoff from farm fields.

"While irrigation improves yields and reduces the risk of crop failure, the environmental cost of mismanagement can be sizable. Over-irrigation reduces yields, leaches fertilizer, and wastes water and energy. Under-irrigation reduces nitrogen and water use efficiency, and depresses yields," according to a project summary.

"Currently, farmers use a combination of evapotranspiration, soil feel, instinct and experience to determine when to irrigate their crops. Each of these methods requires a grower to estimate the soil moisture status of each field," the summary continues.

"It kind of takes the guesswork out," said James Adkins, University of Delaware Extension engineer and coordinator of the project. "The response has been very positive."

Adkins anticipates placing three to four sensors in each field using funding from a Sustainable Agriculture Research Education (SARE) Grant.

The project is 95 percent grant funded, he said.

Sensors will be placed at different soil depths depending upon which crop is planted. Soybean moisture sensors can be placed at approximately four-, eight- and 12-inch depths, while sensors in corn fields will be placed slightly deeper.

Placing the sensors in various locations will help give a better picture of the moisture needs of that particular field, he said.

It's not a new technology and the idea has been tried before, but with a difference, Adkins explained.

Earlier Sussex County trials on corn crops in 2009 to 2011 showed promise, but the upcoming tests will allow farmers to download data much faster and easier. Before, Adkins said, a farmer had to go to an individual field and then download data, a process that could take 20 to 30 minutes.

Beginning next year, the farmer should be able to access their field moisture data with either a smartphone or laptop computer without having to travel to the site each time. The idea is that it is quicker and easier, thus making it more likely to be used.

"The Irrometer Watermark 950R data logging system located at each farm will be upgraded to include a cell modem that will automatically post soil moisture reports online through the manufacturer's online report system," according to the project summary. "Soil moisture data will be available in real-time to each cooperator via a computer Internet connection or smartphone. Immediate access to soil moisture levels will greatly improve the irrigation schedule as the participants will not have to drive to the field with a laptop and manually download data. Online data access will also permit the project team to view the statistics of how often the grower checks the data, and fix problem sensors without long periods of data loss."

The technology is expensive, costing an estimated $1,500 for a 100-acre field, although the sensing equipment is expected to have a long lifespan, thus making the cost more palatable, Adkins said. There is no cost to farmers taking part in the study.

Here are some details of the study:

20 new producers will be selected by the project team for the demonstration of the field monitoring equipment based on interest they expressed at winter meetings. (May 2013 and 2014)

2. 400 growers will receive invitations to attend irrigation workshops at Delaware Ag Week. (November 2013 and 2014)

3. 200 producers per year with center pivot irrigation will attend irrigation management workshops that discuss the findings of the 2013 and 2014 field research. (December 2013 - January 2014)

4. 45 growers representing 9,000 acres will adopt soil moisture monitoring to manage irrigation. (2014 growing season).

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