Top Crop Manager

Irrigation
A model irrigation program

Staying on top of soil moisture allows better irrigation management.


March 4, 2008
By Rosalie I. Tennison

Sometimes it is difficult to gauge how much moisture the crop has and whether it is time to turn on the pivot. For some growers, the only way to ensure the crop has the moisture it needs is to set a timer to turn the pivots on and off, particularly if there are a number of fields to monitor. As farms get larger or spread out as land is rented several miles from the home site, it becomes a challenge for potato growers to ensure the crop is looked after. Now, a computer model, successfully adopted in Alberta a few years ago, to assist growers with irrigation decisions is being introduced to Manitoba growers.

“This model hasn’t been embraced yet in Manitoba because it is new, but it has the potential to assist growers to make informed decisions about managing their water resources,” says Brian Wilson, an irrigation extension specialist with Manitoba Agriculture, Food and Rural Initiatives. “We introduced the Alberta Irrigation Management Model (AIMM), which is a database manager that reflects what is happening with moisture in a field.”

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Photo By Rosalie I. Tennison.

Ted Harms, the irrigation specialist who developed the program at Alberta Agriculture and Food, says it is adaptable to all situations, which makes it useful for more growers. “Even in Alberta we have different climate areas and growing conditions, so it is important that the program could be adapted,” he explains. “The model includes a crop coefficient curve and growers input the factors that affect transpiration in their area. The curve is unique to each crop, so relevant information can be generated.”

Harms says he encouraged the use of soil moisture sensors in the past to get growers to monitor their soil moisture, but they were not accepted by growers who found collecting the data was time consuming. He says that some form of moisture monitoring is not only good for the crop, but also is good for the environment by more effectively managing water resources. “With this model, growers get a seven day prediction of what is happening in the field,” explains Harms. “This can help growers plan their irrigation.”

“This program encourages growers to make some decisions on how to irrigate the field,” adds Wilson. “Growers can decide how dry to let the soil get before beginning irrigation. The model predicts two or three days in advance of when the crop will need moisture. If the weather changes, the model adjusts.”

Harms says the irrigation model has been more readily accepted by growers over the moisture sensors because more information can be generated in an easier, interactive way. He says his team provides training and support on the model, so growers can understand how it can work for them and also to help them get comfortable with the programming. “This is another useful tool for growers,” says Harms. “It can help them manage their resources and crop production.”

Wilson is excited by what he saw in the program during demonstrations in 2007 and sees it as a very helpful tool for Manitoba potato growers as well. “You don’t want to over irrigate because that could lead to disease issues, but you also don’t want to stress the crop with under irrigation. This model helps growers stay between the lines.”

Growers interested in learning more about the model can download it from the Alberta Agriculture and Food web site (www.agric.gov.ab.ca). Wilson says Manitoba weather data is available on-line for producers to put into the program to keep it current and relevant to the province’s conditions.

“Confirming the moisture status of the field, whether using a shovel, an auger or some other method, is still important when using the model,” says Wilson. “It is easy to adjust the model on the computer to reflect what is actually happening in the field.”

Harms agrees. “Growers might not make decisions based on the model alone, but the model gives them more information on which to make decisions,” he adds. “When growers are comfortable with the technology, this is a useful tool for them.”

Monitoring moisture from the truck can be a time-consuming activity, particularly if a grower has a lot of ground to cover, and setting pivots on a timer could encourage disease problems and may not be wise management of water resources. Both Harms and Wilson believe the irrigation model can eliminate some of the guesswork and reduce travel time. -end-