It’s a bit too easy, particularly in the rush of spring, to forget about what might be going in your forage fields, or more accurately, underneath them.
“Forage fertility is often overlooked,” says Mike Howell, senior agronomist with Nutrien. “Farmers tend to think of themselves as cattle producers and are not always focused on fertility needs as long as there’s grass growing. But I want them to think of themselves as grass farmers and they’re selling their product through the beef.”
Whether you’re growing forage for grazing, hay, or both, Howell’s point is a good one — an informed, balanced nutrition program is going to yield the best results, be that in pounds of beef or bales of hay. So if you have some neglected forage fields, perhaps this is the year to take time to check up on them — nutritionally speaking.
What’s in your soil?
“I recommend farmers start with a soil test,” Howell says. That may seem too obvious to mention, but it’s surprising how often forage crops are left to fend for themselves, then tilled under when they stop performing.
According to a recent Beef Cattle Research Council (BCRC) report, only 25 per cent of pasture and hay fields in Canada are fertilized and even fewer alfalfa fields (15 per cent) are given any nutrition. Yes, multi-year forage stands do see a natural yield decline over their lifetime. But it’s also true that a well-timed and well-planned nutrition program can rejuvenate a forage stand and maintain higher yields and quality. It makes you wonder how much money is being left on the table due to low forage-fertilization rates.
Soil testing is the only way to find out what nutrients are available for your forage crop and what the supplemental fertilization needs are. Early spring or late fall are ideal times to test, but Howell says if you haven’t done a soil test in a while, do it now and get a snapshot of what’s going on in the field.
Be sure to do proper representative sampling across the field and sample at different depths to get an accurate picture. Phosphorus and potassium, for example, tend to remain stationary close to the surface while nitrogen and sulphur tend to migrate deeper into the soil.
What forage wants
“Any forage is going to need the 16 essential nutrients, particularly the main three,” Howell says, adding those three are nitrogen, potassium and phosphorous. The full 16 include sulphur (important for soils with low organic matter), micronutrients (boron, copper, iron, etc.) and elements from the environment, such as carbon, which plants obtain from the air.
As with any annual crop, forage nutrition needs vary depending on type: grass, legume or a grass/legume mix. “The main difference between grasses and legumes is the need for nitrogen,” Howell says. “Legumes are not going to need as much because they manufacture their own.”
Having said that, the older a legume crop is, the less efficient it is at fixing nitrogen, so don’t assume your alfalfa doesn’t need a nitrogen top-up simply because it’s a legume.
As with annual crops, nitrogen is the driver in a fertility programme. Grasses and legumes remove more nitrogen from the soil, by far, than any other nutrient, and forages overall remove more nutrients in total than annual crops, largely because nutrient-laden straw is taken off the field as hay so those nutrients are not returned to the soil. “Every time you’re cutting that hay you’re removing nutrients,” says Howell.
How many cuts you plan to get from a field, or whether it’s going to be cut at all and just grazed, along with the type of forage being grown and soil type all factor into building a good fertility plan. Howell says growers should fertilize according to soil test results, and if you’re unsure, consult an agronomist or extension service to help figure out what will be best for your situation.
“You definitely need to manage forages like they’re a crop,” he says. “With a good nutrition plan, they’re going to grow a lot better, they’ll be a lot healthier and you’ll get more forage production.”