Turning centuries of vegetable-garden wisdom on its head isn’t what she set out to do, but Jean Reeder is quickly becoming an advocate for “less is more.”
“People have this belief that ‘if it’s organic, it’s good, and if a little is good, a lot is better,” said the soil scientist. “We’ve got to get away from that kind of thinking. If you’re in the ‘amend every year’ crowd, you might also be in the ‘over-amended group’ as well.”
Reeder was speaking of the manures and manure-based composts that are often added to gardens in spring.
The problem lies not in the traditional wisdom of tilling manures into the soil to enrich it. Instead, it’s the salt and excess nutrients that wind up in the waste of animals kept on high- performance diets in confined areas.
“When Grandma used to put cow manure on the garden, chances are those cows were only fed grass and grain. Now, beef and dairy operations are feeding the animals a concentrated diet because they’re thinking of cattle gain or milk production, not about the quality” of the livestock end products that particularly interests gardeners.
Along the Front Range, soil is typically low in organic matter, said Reeder, a retired U.S. Forest Service soil scientist who now consults with Colorado State University’s Soil Testing Lab. To combat this, gardeners often ritually amend with aged or composted manures. But over-amending can lead to excess salinity and nutrients in the soil.
Amendments aren’t regulated the way fertilizers are; companies don’t have to give consumers a chemical breakdown of what’s in the bag. Common compost products may contain one or more of a variety of plants and manures.
“So salinity and available nutrients can be highly variable because the ingredients are highly variable,” Reeder warns.
Running soil analysis on 60-plus different bagged products, Reeder found that salt and available nutrients not only varied by brand but also occasionally from bag to bag within a brand, with some containing no available nutrients and others overloaded with one or two types.
“If your potatoes have lots of leaves but tiny tubers, that compost probably had too much nitrogen,” she explains.
Supersizing the problem is people’s tendency to misinterpret soil-test language, says Reeder, who notes that many people see the word “adequate” for nutrients and equate it with “not enough.”
“But it is,” she says. “Plants and soil microbes aren’t going to use any more. ‘Adequate’ means plants don’t need more, and no fertilizer needs to be added.”
Add fertilizers when conditions don’t require them, and excess nitrates can leach below plants’ root zone. Phosphorus binds up or can run off and pollute lakes, she said. Routine, unnecessary applications of plant food compounds salinity problems.
“I don’t like blended fertilizers because they add multiple nutrients, whether or not they’re needed. If you’re low in phosphorus, add phosphorus; if you need nitrogen, add that. Generally, phosphorus and potassium are not deficient in our soils.”
So, how can you keep your soil safe?
Remember that manure-based products are highly concentrated. Once per year, spread 1 inch across the surface of the soil and till it in to a depth of 6 inches.
“Because it’s likely to be salty, use it sparingly — don’t try to go from 0.5 percent to 5 percent organic matter in one year.”
Building healthy soil takes time, said Reeder. Impatience leads to problems. If your soil becomes too salty from too much compost added at once, fixing it will require leaching with high amounts of quality, non-salty water.
Avoid problems by using plant-based compost, as well; it’s usually not overly salty. Once your soil’s organic matter is at five percent — ideal for gardens — stop amending and use any of your remaining plant-based compost as mulch.
“We need to be listening to our plants more,” says Reeder. “Watch them. Are they pale? If they show signs of nitrogen deficiency, spot treat them with a small shot of bloodmeal. But ultimately, the thing to do is to have your soil tested. Testing takes the guesswork out of your soil’s growing potential.”
Read Carol O’Meara on her blog gardeningafterfive.wordpress.com/
No studying required
Getting your soil tested by the Colorado State University Soil, Water & Plant Testing Laboratory is easier with specially designed soil test kits — consisting of a container, instructions and the necessary forms. The kits are free; the price for a soil test varies, but the basic one is $28.
There are no grades and no extra credit, but there are specific techniques to follow in testing your soil. The quick overview: You want it to be fairly dry; you want to dig straight down 6 to 8 inches (4 inches if the soil you’re concerned about is a lawn) with a clean, rust-free tool. And you want to get a composite sample — so you’ll dig about 6 holes and mix all those samples well in a plastic or stainless steel container (not galvanized or brass). Air-dry the sample well — for about 12 hours — but then pack it up and get it to the lab.
For more information about soil tests, check out soiltestinglab.colostate.edu or call 970-491-5061.
Among the garden centers carrying the kits:
Ace Hardware, Johnstown; 970-587-4476; johnstownacehardware.com
Ace Hardware, Wellington; 970-568-0223; acehardware.com
Ace Hardware Poudre Valley; 970-221-5300; pvcoop.com
Bath Nursery, Fort Collins; 970-484-5022; bathgardencenter.com
Castle Rock Gift & Garden; 303-688-6800
City Floral Greenhouse, Denver; 303-399-1177; cityfloralgreenhouse.com
Creek Side Gardens, Littleton; 303-933-8493; plantsbycreekside.com
Edwards Flowerland, Fort Morgan; 970-867-5211; edwardsflowerlandco.com
The Flower Bin, Longmont; 303-772-3454; theflowerbin.net
Fort Collins Nursery; 970-482-1984; fortcollinsnursery.com
Fossil Creek Nursery; Fort Collins, 970-226-4924; fossilcreeknursery.com
Front Range Gardens, Broomfield, 303-469-3369; frontrangegardens.com
Garden Country Nursery, Broomfield, 303-466-6761; gardencountrynursery.net
Gateway Garden Center and Home Center, Loveland; 970-667-2932;
Gulley Greenhouse, Fort Collins; 970-223-4769; gulleygreenhouse.com
Hilltop Gardens Nursery and Landscape Co., Federal Heights; 303-465-2226; hilltopgardening.com
Jared’s Nursery, Littleton; 303-979-6022; jaredsgarden.com;
Jax Mercantile, Loveland; 970-776-4540; jaxmercantile.com
Jax Ranch and Home, Fort Collins; 970-484-2221; jaxmercantile.com
McGuckin Hardware, Boulder; 303-443-1822; mcguckin.com
Nick’s Garden Center, Aurora; 303-696-6657; nicksgardencenter.com
Niemann Gardens, New Castle; 970-984-3850; niemannsgardens.com
Pope Farms Produce and Garden Center, Greeley; 970-330-5907
Urban Roots, Denver; 303-893-4064; urbanrootsdenver.com
Wildflower Farm & Colorado Alpines, Edwards; 970-926-5504
The Windsor Gardener; 970-686-9771; thewindsorgardener.com
— The Denver Post
