It could be time to consider a shift in your crop rotations to water-loving and water-using crops. Manitoba farmers in the Red River Valley clued into this some time ago. And it’s no wonder — excess moisture has become the norm in that area. But as the 2011 seeding season looms large, farmers in a huge swath of the Prairies are dealing with wet to very wet conditions (check out Les Henry’s map on page 18 to see just how big an area it is).
For some, 2011 may be an anomaly, for others seeding into wet soil is becoming an increasingly troublesome trend. While there are several considerations to be made regarding fertility, compaction and disease levels, your first decision when dealing with wet soils is choosing what crop to grow.
Some crops fair OK in standing water for brief to extended periods of time (see sidebar for a run-down of best to worst). For fields with relatively common but short-lived ponding, choosing what crop to grow may simply be a matter of choosing out of the top five. But for those with constant moisture, unseeded, wet acres from 2010 or for those who are bullish on this wet cycle continuing, a longer-term strategy of growing different crops might make sense.
There are three strategies for dealing with excess moisture: plant crops that tolerate it, choose big water users, or when time is short, plant a rescue crop. The first strategy, as noted, is to choose crops that don’t mind wet feet. While the common crops might be easy enough to work in to rotation, those dealing with long-term wet conditions should start looking outside that list.
Various perennials and pasture grasses can handle really wet conditions, such as reed canarygrass, and bird’s-foot trefoil. Winter wheat and perennial rye offer cover and make use of early moisture, and due to crop staging can usually tolerate a bit more ponding. Just make sure you’ve got a market for whatever crop you grow.
Soybeans, as noted, can tolerate ponding the best, so it’s no wonder Manitoba farmers have been enjoying such success with this crop.
If you’re looking for a crop to soak up some of that water or to increase infiltration, large tap-rooted crops or perennials are the way to go. Sunflowers fit that bill, but they’re really only suitable for small areas of the Prairies. Alfalfa, on the other hand, does well just about anywhere. Alfalfa can use 20 inches of water in a season and will root down 14 inches, creating huge pores for the water to flow down after the crop is taken out of production. For those looking for long-term improvements to drainage, alfalfa fits the bill. Oh,
and there’s that handy nitrogenfixation side effect, too.
When seeding a forage, you’ll have to decide what to do with the crop — harvest for seed, hay it or graze it. All are viable options, but the one that’s best for the land is grazing, as it returns most of the nutrients back to the soil. And no one is expecting you to go out and buy cows or sheep. Find a neighbour who can make use of the pasture and work out a deal. Portable fencing can work wonders. Desperate times call for desperate measures (though a mutually beneficial arrangement should hardly be considered desperate).
When all else fails, it’s better to have something productive growing than nothing. Martin Entz, professor at the University of Manitoba, says, “Fallow is trouble. It’s hard on biology.” Soil is meant to grow something, all the time. What it produces is really up to you. And here’s where it gets really interesting.
Let’s start with ideas most people are going to be comfortable with. When time is short, you’ve got some short-season options, such as Polish canola, camelina or buckwheat, or you could switch to a crop that, in theory, does a bit better with frost (like flax). But there comes a time when the goal shouldn’t be to necessary produce a crop, but to simply get the ground covered and water used up. That’s where rescue crops come in.
For ground cover, clovers work well and will offer some nitrogenfixation, though not a lot in only one growing season. For the truly adventurous, there are some rather exotic options, such as lablab and mung bean, that will love the heat of summer and are huge water-lovers. Millets will also grown nicely. Each of these options could then act as a cover crop for winter wheat, be sprayed out in the fall or some, like the tropical species, should die out on their own over the winter.
Entz says that any crop cover is going to help keep weeds in check, reduce wind and water erosion, keep soil microbes happy and can reduce upward movement of salts in the soil profile. Yes, letting fields dry-out on their own will work, however, as water evaporates it pulls the salts up with it, leaving salinity in its wake. Having a crop use the water deeper down in the soil profile will keep the salts where they belong — down below.
Best to worst:Crops that can handle wet feet
Soybeans Oats Winter wheat Sunflowers Flax Wheat Canola Barley Peas Dry beans/lentils
Fallow is trouble. It’s hard on biology