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Controlling moisture to maximize productivity in the root zone


November 30, 1999
By Dan Woolley

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Scott Anderson, Agriculture and Agri-Food Canada’s regional agro-climate specialist for Atlantic Canada, has a formula for soil-water management – maximize productivity in the root zone.

Scott Anderson, Agriculture and Agri-Food Canada’s regional agro-climate specialist for Atlantic Canada, has a formula for soil-water management – maximize productivity in the root zone.

This is a bit more difficult than it sounds, says Anderson, as the root zones of plants can vary from less than 12 inches to four feet deep, with most of their water intake occurring in the top half of their root zone. There are published guidelines to help growers manage soil-moisture levels or they can use soil-moisture probes, he advises, adding that he encourages farmers to have a soil-moisture probe in their truck. He also recommends that growers track the rate of evapo-transpiration from their crops.

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During the past 10 to 15 years, three of the driest and two of the wettest summers on record have occurred in the region, says Anderson. “Extreme events are really hard to deal with. One hundred millimetres of rain at one time is not ideal.”

It’s a view shared by growers in the Atlantic region.

“Most of us can agree that we are seeing more extreme events,” says Greg Webster, a berry grower from near Cambridge, N.S.

“It is extreme events that cause crop losses,” says Rolf Meier, a strawberry producer from Kingston, N.S., adding he feels most growers can adapt to long-term climate change.

An example of that adaptation is the fact “tile drainage is making a comeback,” says Anderson. “We tend to get more wet than dry periods.”

He recommends spacing tile drainage to get the desired water table level and fitting drainage outlets with controls to maintain the soil-water level. He also suggests using tillage equipment – such as a furrow dammer – to control erosion and retain soil moisture.

“Have the ability to control moisture,” says Anderson. “Take the uncertainty out of the weather.”

A way of removing uncertainty about moisture delivery is to shift to irrigation.

“I see more irrigation if summers continue warmer,” says Anderson.

Used correctly, irrigation can provide optimum productivity, but he cautions growers to be careful not to overwater, which can lead to leaching.

Anderson says trials have shown that drip irrigation at the surface has a 110 per cent increase in productivity, while underground drip has a 176 per cent increase in productivity in potato trials.

Anderson has put forward project proposals to fund drainage trials on a few farms in all four Atlantic Provinces.