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Think of composted manure — and the organic matter it delivers — as cheap crop insurance for pastures and hayfields.
When the 2016 drought scorched parts of Ontario, Quebec and the Maritimes, Kathy Fremes noticed something unusual about her hayfields: They looked . . . okay.
Not great, mind you, but in a year when other farmers reported initial hay crops down as much as 40 per cent and measly or non-existent second cuts, Fremes’s 20 per cent drop seemed pretty good. Her secret? It wasn’t pricey miracle fertilizer or a new irrigation system, but something her horse farm has a lot of.
“I spread compost in those fields,” says Fremes, owner of Country Hill Farm near Stouffville, Ont. “I really think that helps my soils maintain fertility and hold moisture.”
Think of composted manure — and the organic matter it delivers — as cheap crop insurance for pastures and hayfields. Compost boosts fertility, improves microbial life in the soil and adds organic matter. The more organic matter a soil has, the more space it provides for air, moisture and plant roots.
That in turn makes your pasture more resilient and better able to tough out extreme weather. A one per cent increase in soil organic matter boosts the pasture’s water-holding capacity by roughly 75,000 litres per acre. Imagine the benefits during heavy downpours, when your pasture can suck up water and prevent runoff. Now, think how handy that moisture will be when a drought hits.
Juan Alvez, technical co-ordinator for the University of Vermont’s pasture program saw this first-hand as he studied ways to boost pasture output on a Vermont dairy farm. For three years in the early 2000s, Alvez tested a range of soil amendments, including organic sources of nitrogen, phosphorus and potassium, lime and even crushed crab shell, and fertilizers made from fish by-products and seaweed. None boosted yields as much as composted cattle manure.
Even an irrigation system — rigged to automatically supply water whenever ground sensors detected a moisture deficit — didn’t stack up against compost. Irrigation boosted yields by about .4 tons, or 800 pounds of dry matter per acre. Compost equaled or bettered those increases.
“Even without irrigation in a dry year (2003), compost increased forage yield 0.7 to 1.0 tons/acre, and increased legume content 4 to 11 per cent, thereby improving forage quality," Alvez wrote in a report on the project.
“In terms of hay price this increased yield would be worth $140 to $200 per acre,” he explains. “Therefore, compost answers the farmer’s question, ‘Does it pay?’ with an unqualified ‘Yes!’”
“You can’t control weather or the markets,” Alvez adds. “But you can control what you do on your own farm. If you have the availability of compost, why not use it? “
Livestock do a nice job of producing manure, but the transformation into compost demands time and effort. Successful composting requires the right mix of raw ingredients (typically manure and bedding on livestock farms), combined with air, warmth, moisture and microbial action. When bacteria break down manure and bedding, the result is a stable, lighter, less odorous product that holds relatively more nutrient value than fresh manure.
Those busy microbes also produce heat, killing weed seeds and pathogens as temperatures rise into the 50-70 C range. At the end of the process, nitrogen is bonded with carbon to create a stable, slow-release fertilizer, while phosphorus is made easily available to plants. Because it’s more granular and less clumpy than manure, compost is easier to spread on pastures and hayfields.
Back in 2002-03 Western Beef Development Centre researcher, Bart Lardner compared the use of feedlot manure and composted manure on two 15-acre paddocks near Lanigan, Saskatchewan. Lardner says both manure and compost produced more grass but compost offered some bonuses.
Manure boosted yields by 81 per cent, but compost hiked output by 131 per cent. It also raised the protein content in the grass. Equally important, 1.5 tons of compost packed the same nutrients as about two tons of manure. “With fresh manure, you're really hauling a lot of water, and that adds a lot to weight,” Lardner says. “Composting is a way to reduce water and weight, and make a material that's more nutrient-dense.”
These benefits come at a cost though. It takes time and effort to mix and aerate manure, and convert it into compost. Lardner used a commercial tractor-driven windrow, with estimated costs to transport, handle and turn the compost pegged at $6-$8 per ton. Small farmers can make do by mixing the manure pile with a loader tractor, and letting it cook and cure for a few months.
Fremes uses a two-bay system, with a concrete floor and walls and an arched tarpaulin roof to keep the rain out. Bedding, manure and sometimes grass clippings are mixed together in a bay and left to heat for about six months. Fremes stirs the compost occasionally with her own loader tractor or hires a contractor to do the mixing.
"It's a little bit like making a cake. You have to get a feel for what you're looking for, in terms of moisture and temperature,” she says.
Once you get the hang of it, the effort pays off in better forage yields, more resilient pastures, and effective nutrient cycling. Besides, Fremes says, returning all those nutrients to the earth is just good stewardship. “I think if you’ve got land, you should be looking after it and protecting it — that’s part of the deal.”
Tips for wannabe composters:
- Check your province’s nutrient management regulations. Some agriculture or environment departments offer advice or guidelines for composting, or regulate larger composting sites.
- Aim for a 30:1 mix of carbon to nitrogen. Cattle or sheep manure mixed with straw or waste hay composts well. Horse manure has less nitrogen, so you may need to reduce bedding or supplement with grass clippings or chicken manure. Chicken manure has a lot of nitrogen and may require additional carbon (leaves, waste hay, etc.)
- Turn the pile to aerate it and enhance microbial activity. Some enthusiastic composters turn the piles once a week during warm weather, but once or twice a month should suffice for busy farmers.
- Use a compost thermometer, available from garden centres or mail-order catalogues, to track the heat generated by microbial activity. When the pile no longer generates heat after turning, it’s through its rapid composting phase and can “cure” for weeks or months before final application.
- Keep compost about as damp as a wet, wrung-out sponge. If it’s too dry, sprinkle with water. If too wet, turn, and consider adding some dry material, or covering the pile with a tarp to shed rain.
- Piling manure and letting it sit is not composting. Without mixing and aeration the result is an inconsistent product that’s harder to handle and spread.
- Keep tabs on soil fertility with regular soil tests. Target compost to phosphorus-poor fields. Avoid applying phosphorus-rich compost on fields that already have high phosphorus tests.
- Boost organic matter on pastures with good pasture management. Use rotational grazing to spread dung more evenly, and leave at least three inches (about 7 cm) of grass on the field after grazing to capture nutrients and help rainfall infiltrate into the soil. If in doubt, “take half, leave half” offers a rough guide for moving livestock off a pasture.
- Ray Ford