Is your soil safe? Experts offer testing tips
Spring weather may have encouraged some gardeners to slide on their best gloves and boots, but before any seeds touch the dirt, experts say some time should be spent in the soil.
It's a bit early to start digging, but there's no harm in being ready, said Jess Hyman, executive director of the Vermont Community Garden Network.
While the last banks of snow melt away, gardeners could get a jump start by testing the foundation of their plot to make sure soil is safe and nutrient rich, she said.
"Good soil is the foundation for a healthy and productive garden," she said. "Growing good soil is part of growing your veggies."
Knowing the Earth
To start, gardeners should know what's in the ground.
Soils vary greatly throughout Chittenden County, Hyman said. In the Old North End of Burlington, the soil is sandy — perfect for growing asparagus. In the Intervale area, where the Tommy Thompson Community Garden is located, the soil is heavy and good for root crops. Farther south, near Charlotte and Hinesburg, there is clay in the ground, Hyman said.
"One age-old gardener's trick to find the composition of soil is to put about an inch of soil in a jar, like a canning jar," she said. "Fill the jar about two-thirds with water and a teaspoon of salt, and shake."
After several hours the different layers of sand and silt will be visible as they settle into the jar. After a day or two the clay will settle too, she said.
Even amateur gardeners know that fertilizer and compost is needed to keep a garden healthy, but too much of one or other can be problematic, said Joel Tilley, a research specialist at the University of Vermont's Agricultural and Environmental Testing Lab.
Tilley runs the plant and soil science lab, which analyzes soil from farms and gardens for nutrients and heavy metals. Anyone can send a soil sample for testing, he said.
The lab sees about 4,000 samples annually, he said. A majority of samples come from Vermont and neighboring states, but Tilley said he has seen some envelopes arrive from Baltimore or as far away as Indiana.
"About half of the samples from come from dairy farms," he said. "Only about two-thirds are from home gardens or lawns."
Envelopes containing a soil test submission form, a plastic bag for one half of a cup of soil can be picked up at UVM Extension offices and from some area garden stores. Individuals can send up to 10 soil samples at one time, he said.
For $14, an individual soil sample is given a basic nutrients test, which includes the pH level and levels of potassium, phosphorous, calcium, magnesium and sulfur, micronutrients and organic matter.
Soil samples can be mailed or dropped off at the lab in Jeffords Hall at UVM, where Tilley then ships them to the University of Maine for testing.
"It is cheaper to do the testing there and have them send the results to me," Tilley said. "We do a lot of soil analysis here."
It takes about two weeks for results to return, he said, but each report comes back with comments and a fertilizer recommendation for one crop. Recommendations for additional crops on the same sample are $2 each.
"It is now possible for us to generate reports as PDF files that we can email our customers," Tilley said.
Some gardens may need bone meal or wood ash to add additional phosphorus and potassium. Others could call for a 10-10-10 fertilizer to add a blend of nitrogen, phosphate and potassium.
While nutrients are necessary for a healthy garden, too much nutrients can be problematic for gardeners, Hyman said. Commercial fertilizer contains nitrogen, phosphorus and potassium, but many gardens wind up with a lot more of one element and not enough of the others.
"A lot of gardens wind up with too much phosphorus from really rich compost or manure," she said. "When you have too much of any of these things that will affect how plants grow, so you have to balance them out."
Tilley said farmers and gardeners should know how to improve their plots.
"I encourage people to take the systematic view of gardening," he said.
That includes improving the safety of soil. For an additional $10, the lab will conduct a heavy metals test on soil samples to look for materials such as nickel, cadmium and chromium.
"If you're doing any type of urban gardening this is a really important thing to do," Hyman said.
Lead is the most common heavy metal found in soil samples, Tilley said. That could be due to lead paint scraped off of old houses in the area.
Metals tests are recommended only if a gardener has reason to believe their garden could be contaminated.
Hyman said lead is one of the worst contaminants in soil because the metal can be absorbed by vegetables, especially leafy greens.
"It's important to create a garden space that is safe and healthy," she said.
There are no restrictions on where a garden plot can be placed on a property, Hyman said, but if a space if not big enough or safe enough to grow food, containers can help.
Raised beds have become a popular way to grow food, especially in cities, she said. These beds can be built from recycled materials or wood and can be filled with good, safe dirt.
"You can grow a tremendous amount of food in just a 5 gallon bucket," Hyman said.
Community gardens are an alternative to planting at home. Most of the sites in Burlington are full as gardening has become more popular, she said.
The Vermont Community Garden Network offers a class for beginners that covers all aspects of vegetable gardening. Participants have instruction twice a week, individual and shared garden space and access to tools, Hyman said.
"A lot of people are getting excited about gardening," she said. "After just a season of growing your own food, there's this incredible confidence and joy that comes with it."
Contact Haley Dover at 660-1850 or email@example.com. Follow Haley on Twitter at www.twitter.com/HaleyRDover.