Fruit & Vegetable Magazine

Equipment Irrigating
Regulating water input vital to producing healthy potatoes

November 30, 1999  By Myron Love


Dr. Jazeem Wahab is a researcher at the Canada-Saskatchewan Irrigation Diversion Centre and is well versed in the role of water and how best to manage its use in potato production.

Dr. Jazeem Wahab is a researcher at the Canada-Saskatchewan Irrigation Diversion Centre and is well versed in the role of water and how best to manage its use in potato production.

He notes that growers have to know the right amount of water to use. Too much water delays emergence, leaches nitrogen and can cause decay in seed pieces, he says

Too little water – even 10 per cent less than needed – slows growth and can bring growth to a halt entirely.
He also lists the various potato diseases that can result from too much or too little water at the different stages in the potato’s development.

“The goal is to maintain an adequate amount of water throughout the potato’s growth cycle,” Wahab says.
He lists a number of steps in establishing an irrigation system in your fields. First, growers need to estimate the field capacity and calculate the depth of the crop roots, he says.

“You should irrigate when the soil moisture has been depleted by 35 per cent,” he says. “You have to monitor the moisture levels and make adjustments to match field conditions and weather conditions depending whether it is sunny, cloudy or rainy. The sun is the most serious problem in July and August.”

He outlines a list of irrigation guidelines. His first recommendation is to avoid planting in soil that is too wet or too dry. If the soil is too dry, irrigate before planting.

In the second stage of growth, soil moisture should be maintained at 75 to 85 per cent, he says. In the third stage of growth, he suggests that 65 per cent soil moisture is adequate in Saskatchewan.

“The highest water demand is in the fourth stage of growth,” Wahab says. “You need to maintain moisture levels between 80 and 90 per cent. Anything less will cause stress and result in reduced yields and quality and can lead to disease.”

In the last stage of growth, moisture levels need to be lowered to 60 to 65 per cent, he says. Too much water at this stage can result in pink rot or pythium leak. Too little water at this stage can produce black spot.

The type of potato producers are growing has to be factored into the amount of water needed. Norland is the most efficient in its use of water and produces better yields, Wahab says, adding that Burbank and Ranger are the least efficient in their absorption of water.

Ranger Russets need adequate moisture in the early stages of growth and need more water than Russet Burbank and Russet Norkotah varieties, Wahab says, while Shepody varieties need more irrigation.

Wahab notes that tillage influences water infiltration and surface run-off. While compaction reduces a field’s water-holding capacity, hilling reduces infiltration.


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