GRAND FORKS – The BC Ministry of Agriculture and Food sponsored a series of soil field days in conjunction with Kootenay Boundary Farm Advisors group in early October.
“Our purpose is to help you understand the basic techniques of soil sampling and why you would do it,” says soil carbon agrologist Ahmed Lasisi, who led off the October 8 session at Kettle River Farm in Grand Forks.
Only when you know what’s in your soil will you know what you need to add, Lasisi explains.
“If you are adding any kind of inputs into your soil, it makes sense to know what is in there first,” he says. “Soil testing gives you the information you need to plan nutrient applications in order to maximize your crop production, your economics and the environment. Imagine what happens when someone’s crop only needs 50 pounds of nitrogen, but they apply 100 pounds.”
Lasisi led participants through the process of collecting a soil sample, something he says doesn’t have to involve special equipment.
“You want to gather an aggregate sample of your field based on one management zone, such as fields that look alike, or what crop the farmer grows there,” he says. “For a field up to 10 acres, you would need 10 to 15 samples.”
Consistent sampling around the same time every one to three years will reveal trends.
“Fall will give you an indication of the post-harvest uptake of your crop and give you time to complete the lab work and plan for spring,” Lasisi says. “In areas where high winter rains or snowfall could cause nutrient leaching, a spring sample will be a more accurate picture of what is available at the start of the growing season, but the lab results may not be back in time for your planting as they could take three to four weeks.”
Regardless of the time of year, growers must wait two months after a nutrient application before sampling their fields, Lasisi cautions.
A soil probe is a handy tool, but a shovel or trowel are equally effective.
“It is important to take a representative sample from different typical areas of your field, but avoid weird areas such as a low-lying spot, where soil has been eroded or where you load your spray tank,” Lasisi notes. “Clear away any surface residue so plant matter is not included and collect a sample of the first 15 centimetres of soil.”
Growers should mix the samples thoroughly in a bucket, dry them away from direct sunlight, then bag approximately two ounces and send them to a lab.
Testing is only the first step. Knowing how to interpret the results and action them is critical.
Fortunately, all workshop attendees will have the costs of a soil sample covered by the ministry and staff are available to help with interpretation and recommendations.
“We hope to do more of these workshops and start to build a repertoire of what’s happening with soils across the province,” says regional agrologist Lindsay Hainstock.
Overall soil health isn’t strictly about chemistry, notes Josh Andrews, a nutrient management specialist with the province.
“Soil has to be healthy in order to perform the functions that you want it to,” he explains.
There are many online guides available to soil health, including the app LandPKS.
“There are lots of indicators to look for and ways to measure them,” Andrews says.
He led the group through a variety of field measures.
“You want to be looking over time to see what is happening in the context of your management practices,” he says.
“These will all help you evaluate the soil’s ability to grow crops, hold nutrients, infiltrate water or support recreation,” Andrews says.
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