Shotgun Silage, Grazing Mixes Tested

“The quality that brings to your soil is huge. You get better water infiltration, water and nutrient holding capacity, tilth, aggregation, and all sorts of good things.”

– SUSAN AINSWORTH, MAFRI

On Bernie Dueck’s farm near Sidney, the crop is coming up gangbusters.

That’s right, in five-acre strips, there’s a whole whack of plants emerging, everything from daikon radish, peas, barley, vetch and turnips to millet – a veritable shotgun blast of crops, sown all together between check strips of forage barley.

The peas have already begun fixing nitrogen from the air, with tiny nodules appearing on the roots.

It’s part of a Manitoba Agriculture, Food and Rural Initiatives polyculture project that began last year with six farms.

This year, it will see 10 test sites on 10 farms from the Interlake to the southwest seeded to a grab bag mixture of warm-and coolseason plants, including cereals and brassicas. Four sites, however, haven’t been seeded due to wet conditions.

Last year, farmers were able to choose their mix of species and compare performance to a nearby monoculture of either oats or barley. This year, the same mix will be used on all participating farms to reduce variability and improve data consistency.

At the Dueck farm, the mix in pounds per acre was barley 25, peas 75, radish two, turnips two, hairy vetch four, and millet eight.

The barley and millet represented the warm-season grasses, the radish and turnip the coolseason broadleaf crops, and the peas and vetch the legumes in the mix.

Soil analysis prior and after harvest will compare the effect, with a particular eye on nitrogen levels. Weed suppression will also be examined.

The cost of the seed is fairly high, at $50-$60 per acre, but the potential benefits are huge.

“The big thing with having all those different types of roots in the soil is that you’re adding a whole bunch of organic matter,” said Susan Ainsworth, a Carberry-based MAFRI farm production advisor.

“The quality that brings to your soil is huge. You get better water infiltration, water and nutrient holding capacity, tilth, aggregation, and all sorts of good things.”

As part of a number of projects undertaken in the department’s Agricultural Sustainability Initiative, the crops will be cut for silage and the regrowth grazed, providing an extra option for sustaining cattle herd gain rates as pastures dry up and go dormant as they usually do in late summer.

“CONFUSED” PESTS

The project is based on the experiences of polyculture and intensive grazing pioneer Gabe Brown, who reportedly seeded 25 different no-till crops on a portion of his 4,000-acre North Dakota ranch last year.

The goal is to create large volumes of biomass, which will shelter the soil and the microbial life within from the summer heat as well as prevent moisture loss via evaporation.

Mimicking the natural pasture mix makes for a more resilient crop, and the diversity of plants helps to “confuse” pest invaders that spread rapidly and lay waste to monocultures. Some flea beetle damage on the brassicas was evident, however, but it was expected to dwindle as the crop matured.

With the winter-killed crop left on the surface, a mat of surface mulch helps to prevent erosion and also keeps weeds from coming up in early spring, she added.

An additional benefit is carbon sequestration. A one per cent increase in organic matter, which is basically carbon pulled from the atmosphere and sunk back into agricultural soils in the form of plant tissues and roots, also amounts to over 1,000 pounds of nitrogen, 100 lbs. of phosphorus, and an 800 per cent increase in water holding capacity.

“It takes years to increase organic matter, but anything you do will really help increase crop production,” said Ainsworth.

Results from last year’s trials found greater biomass in the polycultures compared to the monocrop, and the greatest difference was found where soil fertility rates were highest.

Farmers set their own fertilizer rates, but, interestingly, in all cases, the plots with the highest biomass yield were those that had the highest number of species seeded.

“In the mixes with the greatest diversity, there was a real improvement in the feed value as well,” said Ainsworth.

Next year, the mix of crops may see some “tweaking” in order to determine what works best in the different areas of the province, she added. Results will be presented at meetings this fall. [email protected]

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