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Radish to the rescue

The last seven-inch rain reduced Elmy's cover crop options to one – Tillage Radish

Seven inches of rain in one shot late last June left Kevin Elmy with little choice but to throw out the notion of generating income off some of his land that year. Instead, he planted the waterlogged fields to Tillage Radish in hopes of at least conditioning the land.

Elmy’s Friendly Acres Seed Farm near Saltcoats, Sask., has been growing cover crop species for a decade or so. Tillage Radish was added five years ago, mainly as part of cover crop mixtures.

He sets up on-farm trials to evaluate the adaptability of forage and field crops introduced to Saskatchewan in the past dozen years. His normal field rotation today is soybeans, canola, winter triticale, short-term alfalfa, and grazing corn.

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The farm has rolling sandy loam and clay loam soil, so there is some natural drainage, but five years of above-average snowmelt and rainfall has taken its toll.

When spring 2014 left 120 acres too wet to seed as usual in May, his initial intention was to wait until he could get onto the land to plant a cover crop of annual ryegrass, Tillage Radish and crimson clover for short-term grazing. The idea was to soak up the excessive water, compete with weeds and salvage some revenue.

Then came a seven-inch rainfall. It drowned out some grazing corn and converted the 120 acres to a sea of foxtail barley. When he was able to get on the land in early August he simply used a disc for the weeds and spikes to level it before seeding straight Tillage Radish at seven pounds per acre.

From experience he knew this seed has great vigour and pops out of the ground quickly when it has good seed-to-soil contact. The main concern is residual activity from herbicides such as Pursuit used on previous crops. It can fry radish seedlings. His rule of thumb is if the field is safe for sowing canola, it will be good for radish.

The August weather was rather unexceptional with daytime temperatures in the low 20 C range and nights between 5 C and 10 C. By the time the first frost hit in September, the radish leaves were six inches in diameter and the two- to three-inch-diameter tubers were a foot long with taproots drilling down 24 to 30 inches.

“It didn’t take a lot of heat or growing days to be frost tolerant and stayed green under the first snow. Three nights in a row of -9 C in late October and it was done. Later seeded, it tried to act like a biennial staying vegetative the first year,” he observes. It is an annual and if planted before the third week in June, it will flower and set seed too early.

Having a tight carbon-to-nitrogen ratio, the tubers and above-ground growth will rot quickly this spring, releasing 60 to 100 pounds of nitrogen per acre. Fair warning, though, rotting radishes do stink, he adds.

The rotting tubers give off heat, helping to warm the soil and the decaying leaf material releases an acid that has some natural herbicide activity. In his experience, leaving the rotting residue on the surface controls weed seedlings between seed rows of the subsequent crop until mid-June. Drill openers push the decaying matter off to the side enough that the acid doesn’t interfere with germination of the new crop.

Elmy says the combination of warmth and weed control creates ideal growing conditions for corn the following year under normal growing conditions. All crops do well following radish, however, it is a brassica, so you could be setting the stage for disease issues by growing canola or other brassica crops directly on the heels of a radish crop.

Elmy doesn’t feel confident jumping right back into his normal rotation first thing this spring because that particular field doesn’t have great topography for drainage should 2015 bring more of the same. Snow cover had been average for the area into February and he expects the land will be OK for seeding if March is kind and there’s an early melt so the water gets away.

Instead, he is planning on growing a spring-seeded cover crop to take off as greenfeed in July. In the meantime, planting the Tillage Radish crop met his goals. It smothered weeds, used water, and the roots made vertical slices that definitely cracked the hardpan as evidenced by September rainfall that soaked away nicely without run-off or leaving standing water on the field.

The overarching goal was to limit losses. As the old adage goes, the first loss is the cheapest. The first loss was losing a year of production from the grazing corn and flooded acres. Chemfallow wasn’t an option for meeting his goals because herbicides are most effective applied when weeds are small, so the weed growth wouldn’t have used much water. There’s always the concern of contributing to herbicide-resistant weed problems with repeated use of the same herbicide group on the same field, as can be the situation during a string of wet years. Compaction is another issue on wet ground as air is pushed out of the soil with each pass.

Goal setting and planning ahead are among the best-management practices for cover cropping that have come to the forefront in the northern U.S. where producers have been cover cropping for longer than on the Canadian Prairies.

“The recommendation is to have seed inventory on hand so that if the opportunity for growing a cover crop is there, you can go ahead and plant it rather than trying to round up seed for the mix you want at the last minute,” Elmy says. Some varieties can be difficult to source on short notice, others are fairly common.

Crops he likes because of their adaptation to the Prairie region include the legumes crimson clover, hairy vetch, sunn hemp, white clover, red clover, alsike clover and fenugreek; the brassicas Tillage Radish, purple-top turnip, appin turnip, forage rape, kale and hybrid brassica (a turnip-radish cross); the grasses sorghum sudangrass, RootMax annual ryegrass, perennial ryegrass, fall rye, winter triticale, oats and the millets; and the broadleafs buckwheat, sunflower, phacelia and chicory.

“Your choice of species and when you seed will depend on your reason for planting the cover crop,” Elmy explains. The most common goals are to smother weeds, break the hardpan, reclaim nutrients, build organic matter, or as a grazing opportunity. The wet years in eastern Saskatchewan and western Manitoba have shown that cover cropping is a good strategy for using excess water.

Commonly a cover crop is planted in spring for greenfeed ahead of a winter annual, and replacing hailed-out silage crops with mixtures suitable for late-season grazing.

In Elmy’s case, if the drowned-out acres were not as prone to flooding, his cover crop goal last year would have been to provide protection for a winter triticale crop. The mixture he plans on using this spring would have been planted in early August with winter triticale seeded directly into it the third or last week of August.

Tillage Radish is a great fit for weed control, reclaiming nutrients and breaking the hardpan, but there are better choices for building organic matter and short-term grazing, he says. High-fibre crops, such as oat are best for building organic matter. For grazing add some oat, winter triticale or fall rye to create fibre. Cattle will readily graze Tillage Radish, but by itself, it’s far too rich in protein at 30 to 35 per cent and has a relative feed value of 275 to 300, compared to the 120 to 140 relative feed value cows need.

For more information visit the Elmy’s Friendly Acres Seed Farm website or give him a call at 306-744-2779 or 306-744-2332.

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