Thinking of purchasing soil or compost for the garden?
As with any long-lasting purchase, it pays to take time to do research and ask questions. Once soil is delivered, it is just about impossible to return.
Bulk soil is usually sold by the cubic yard. Cost between sellers, composition of the soil and delivery charge will vary.
Ideally, everyone who sells soil has sent samples to a lab to test for nutrients as well as for residual chemicals and heavy metals. Landscaping companies and garden centres are more likely to do testing as opposed to trucking companies that sell soil as a sideline.
Always go look at the soil before making a purchase. Avoid soil that is in an area covered with weeds as the seeds are likely to be in the soil. Dig in the soil in a number of places to check to see that the soil is free of rocks, wood chunks, strips of clay and garbage.
Inquire where the soil originated and how long it has been sitting at that location.
The longer it sits, the less likely that there are residual chemicals in the soil. If the soil has not been tested, ask what was growing in the soil before it was removed. Crops that are seeded yearly are less likely to be sprayed with a residual pesticide.
Compost, which includes well-rotted manure, is commonly seen in small bags but is also available by the cubic yard or truck load. In areas where disposal of manure is a problem, companies collect the manure and compost it in long windrows.
It gets turned frequently completing the composting process in less than a season. The original piles of organic material shrink in bulk leaving a concentrated residue.
Companies that compost over 100 tonnes a year must meet provincial environmental regulations, which includes testing for trace chemicals, pathogens, stability, maturity and garbage.
There are no regulations placed on people that compost less than 100 tonnes a year.
Follow the same rules when purchasing compost as with top soil; look before purchasing. A well-composted product should be consistent in shape and texture. It should not contain lumps, twigs, garbage or recognizable bits.
When purchasing compost from a smaller producer, ask what went into the compost. Were the plants composted sprayed with chemicals? If so, which chemicals were used? Do not be surprised if the answer is “I don’t know.” Hay is purchased to keep animals healthy. Manure that can be composted is a byproduct.
Manure makes great compost but there can be problems depending on what the animals ate. Chemicals such as aminopyralid and picloram are registered to kill broadleaf weeds in a hayfield but not for human food.
Animals can eat the sprayed crop and not be affected as the chemicals are water soluble not fat soluble. When hay is treated with these chemicals, the chemicals pass through animals and become part of the manure. If the animals are fed a diet of sprayed hay, the amount of chemicals in the manure pile can be strong enough to inhibit or distort plant growth.
If a herbicide is a problem, the tomatoes and potatoes are likely to be misshapen.
Know that too much manure or compost will also cause problems. Symptoms of over fertilization can include: yellowing and wilting of bottom leaves, brown margins and tips on leaves, rotting roots, slow growth, seedlings germinating but never growing and sudden death of plants.
Take care and do due diligence when adding materials to the garden as the soil is the most important part of the garden. If in doubt, take soil samples and have them tested.
Linda Tomlinson is a horticulturalist who lives by Rocky Mountain House. She can be reached at firstname.lastname@example.org.