Springing into Soil Sampling
How are you starting spring?
At Farming Smarter, we like to start our spring with soil sampling!
Spring soil sampling allows us to know the quantity of nutrients in the field before we seed. It gives us a solid estimate of how accessible nutrients are for crops throughout the growing season.
This means we aren’t overapplying and wastefully using resources, making it a fantastic cost-saving measure!
“Often times, farmers will create zones in their fields so they can target specific spots that need more nutrients. You can save yourself from over-using and wasting your budget,” says Farming Smarter’s Custom Research Lead Trevor Deering.
Routine sampling allows for year-to-year comparisons, making it easy to monitor soil health.
Nutrients can change overwinter, though it is rare for a big change to take place from late-fall to early-spring. By taking soil samples in the spring, you’re getting a better snapshot of what’s going on in your field as close as possible to your seeding date.
“You’ll have a better sense for what nutrients are there. You’ll be able to save on inputs,” added Deering.
In today’s market, with high fertilizer prices, it’s important to stretch inputs as far as you can. With spring soil sampling, you don’t have to guess how much fertilizer to apply.
Digging in the dirt
There are many approaches to soil sampling, from conventional/composite sampling to grid sampling, each has its purpose and own pros & cons.
The most common practice is the composite sampling method, mixing multiple core samples in a bucket and sending them into the lab with a sub-sample.
“It gives you an estimate to the field. There was early work done to find how many samples provide a good test. There’s no sense in doing more than 15-20 samples, but a minimum of 10 is required for a good sample,” says University of Lethbridge’s Sessional Soil Science Instructor and Adjunct Professor Tom Jensen.
Other methods of sampling include benchmark sampling (testing the same spots yearly), zone management (sample 4-5 zones with varying crop yields), and grid sampling (sampling ever 1-2 acres).
However, grid sampling targets the pH level in soil rather than the overall soil health. Due to the cost of the frequent sampling, this method isn’t recommended as a yearly test.
Regardless of method, soil sampling has general guidelines that it helps to adhere to.
“You must know your scale and understand how representative those areas are. Your samples should represent the entirety of your field, opposed to small zones like a low spot or hillside,” said Deering.
“Figure out how intensive you want your samples to be, and where you want to sample in your field. You should know how deep you want to sample as well.”
The depth of your soil sample matters as much as the location of it. Take these two factors into account before you send in your soil samples. Additionally, you should consider how intensive of an analysis you want.
“The analysis depends on what you want to pay attention to – pH, nitrogen, phosphorus, potassium, and fluoride are the standard tests. More detailed tests are available,” said Jensen.
At Farming Smarter, we’ve been testing at 0-6 inches, 6-12 inches, and 12-24 inches. This allows us to test for nutrients that move deep in the soil, like nitrogen. While the standard test works for most crops, specialty crops like sugar beets will require tests as deep as 4 feet.
Soon, Deering and the Custom Research team will be starting a three-year project with Replenish Nutrients Ltd. They’ll study the effect of nutrient trials on soil through intensive soil sampling.
This project is our first small plot trial specifically looking at soil health and will sample more than 200 plots across three locations.
The early bird gets the worm (in the soil sample)!
Collecting soil samples can be as easy as heading into the field with a shovel. While it’s not the flashiest way of collecting soil, it’s by no means inadequate!
Farmers have a lot of choices when it comes to collecting and testing samples. Agronomists, as well as select retail agriculture stores, have the equipment to collect samples from a field and send it off to a lab.
Because you want to receive your results before you seed, the earlier you can get it done the better. As soon as everything starts to thaw up, you want to start getting in the field and taking samples!
“Lots of labs, especially if you have one or two labs in your area, will be congested in the spring. You want to get them in early so you can get them back in time,” said Deering.
Most of the time you can get the results back within a few days, but when the labs get busy it can be harder to get timely results.
“If the lab isn’t busy, you can have the answer back in as early as three days. When the labs are busy, it can take a week,” said Jensen.
If you’re in a rush, most labs allow you to pay extra to have your results expedited.
While spraying/burn down won’t affect your sample, you likely don’t want to be working the soil with your hands afterwards. Follow the instructions on the label to see how long you should wait.