The most important thing to consider when choosing to grow crops is the quality of the soil, and this is especially important for potatoes.
“There are so many factors that come into play when you’re growing potatoes,” says Michael Krawczyk, a senior scientist with the Agricultural Marketing Centre of Canada.
“But the key is to pick soil that’s rich in nitrogen, phosphorus and potassium, and organic matter.”
Soils rich in these nutrients will yield higher yields than those that lack them, Krawszyk says.
That’s especially true if you’re picking potatoes in the summer, when nitrogen levels are at their lowest.
In fact, most of Canada’s soil is nitrogen-rich.
The soil is also rich in organic matter, such as calcium, magnesium, iron, calcium sulfate, potassium, potassium chloride and zinc.
But a large part of the value of soil quality is how well it retains moisture.
Krawczks is the director of soil science and technology at the University of Manitoba.
The best soil to grow potatoes in is one that is well drained, with ample drainage holes, he says.
“It’s like a bucket with a hole in the bottom, so it can hold water and then it’s very porous, and it retains the water.”
In addition, a rich soil should be easy to work with.
A soil that is difficult to work on can lead to soil that will deteriorate in the winter.
Kayser says the soil that you pick is also critical to the soil quality of your potatoes.
“It’s a great time to grow potato,” he says, “because the sun is coming out and the temperature is high and the soil is getting full of water.”
Krawzas potatoes need to be grown in an area that has a good drainage system, so if the potatoes are planted near a stream or river that runs through a sensitive watershed, the soil should not be too acidic.
“If it’s not acid-free, the potatoes won’t be able to withstand the water,” he adds.
In general, soil is more important than water when choosing the type of soil to plant potatoes in, Kaysers says.
But it is important to choose a soil that has adequate drainage holes so that water can flow into the soil from the stream and into the pot.
“The biggest problem we see with potatoes in Canada is that potatoes are grown in wet soils, which is really bad for potatoes,” Krawiczks says.
When soil is too acidic, the water that comes out of the potato can be lost and it will be more difficult to digest the potatoes.
That is why Krawetzks recommends potatoes be grown on a sandy surface, which has plenty of drainage holes.
“And potatoes are best grown on sandy soils, because the soil will retain the moisture that is in it,” he explains.
“So when the soil gets too acidic it’s more difficult for the potatoes to digest and retain the water in it.”
Kays, too, recommends potatoes grown in a sandy soil.
“Potatoes have a very high pH and so it’s important to make sure that the soil pH is good,” he suggests.
The pH of the potatoes is a key indicator of soil pH and how much water it needs to stay in balance.
Soil pH should be between 6.5 and 6.8, depending on the species.
“Ponders, for example, have pH values that are usually between 6 and 7,” Kays says.
For other species of potatoes, “the pH should range between 4 and 5,” he points out.
“We don’t know the exact pH of potatoes in our area, but if it’s low or high, we know that we need to add some water.”
A pH of 5.5 or above will produce good potatoes, while a pH of 4.0 or below will produce poor potatoes.
Kowser says a pH value of 5 or higher is considered good for potatoes, and a pH below 5.0 will produce bad potatoes.
So if you are growing potatoes in a dry area and the pH is high, you may want to start with a pH level of 4 to 5.
The next step in determining what soil to pick is to test the soil for water content.
“In a lot of the rural areas of Canada, we’re looking for potatoes that have a high pH in the soil,” Kives says.
The more acidic the soil around the potato, the higher the pH of that soil is, and the higher that soil pH will be when it comes to water retention.
“That’s why a pH that is low or higher will give you a higher yield of potatoes,” he said.
When you’re choosing soil for potatoes to grow, “it’s important not to plant the potatoes too close to the streams or rivers that are sensitive to erosion,” Kowsers says, adding that a potato planted too close can also result in a potato that won’t grow well