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Grass is a crop too

Just because forage is on marginal land doesn’t mean it should get marginal management, says a recent Beef Cattle Research Council study

If grain farmers routinely fertilize their crops to get higher yields and profits, why don’t forage producers do the same to their pastures?

That question is at the heart of a recent Beef Cattle Research Council study into improving forage yields in Canada.

The study notes that while annual crops have seen significant yield increases over the past 60 years, hay yields in Canada have hardly budged at all. This puts Canada’s cow-calf sector at a competitive disadvantage because the cost of forage per tonne is higher here than in other countries.

“Over the long term, improving forage productivity is crucial for future competitiveness of the cattle industry,” says the study.

It concludes that a major reason for this low productivity is soil nutrient deficiency in pastures and grasslands.

You’d think the solution to the problem would be easy. Fertilize hay lands and you increase forage yields. Greater yields mean higher stocking rates, improved animal performance and a lower cost per unit of production, which translates into reduced winter-feeding costs per cow.

Unfortunately, it’s not that simple. The study recognizes there are reasons why producers tend not to fertilize forages the same way they do wheat and canola.

Marginal land mindset

One reason is economics. As Reynold Bergen, Beef Cattle Research Council’s science director explains, farmers tend to invest heavily in high-value annual cash crops. That involves buying or renting more land for those crops. Doing so increases competition for land, drives up land prices and pushes forage production to marginal land that cannot produce high-value crops. As a result, forage land has lower expectations put on it, along with less investment such as fertilizer.

That’s counterproductive because lower fertility inevitably means lower yields, and low forage yields are the most common reason for terminating a stand, Bergen says.

Reynold Bergen

“If you’re expecting to get yields from a crop, you don’t just need it to get rainfall or irrigation. You need to feed it. It needs nutrients. If you keep pulling off those nutrients without replacing them, you’re going to starve the plants. And that’s why yields go down. So stands get broken up after only a few years.”

Currently, application of fertilizer to forage crops in Canada is minimal. The BCRC study estimates only 25 per cent of improved pasture and hay land is fertilized. Just 15 per cent of alfalfa hay fields receive fertilizer. Given the combination of low nutrient input and the high nutrient uptake by the crop, it’s hardly surprising that forage stands in high-moisture regions of Western Canada are maintained for only three to five years. In semi-arid regions, the average life of a forage stand is six to nine years.

Other reasons why farmers don’t fertilize pastures include high fertilizer prices and poor financial margins (until recently) in the cattle industry. Moisture limitation is another factor. Fertilizer applied to forage is top dressed, not incorporated (as with annual crops). This can result in nutrient loss through volatilization (evaporation of N) in dry conditions, or runoff in wet years, which in turn creates environmental concerns.

Fertilizer considerations

That said, fertilizing forages can produce results. The study cites a 10-year project in Manitoba which showed adding fertilizer increased the productivity of grass pastures when applied to soil test recommendations. The downside was that target yields were often not reached due to moisture limitations.

The type of soil can also influence the effectiveness of fertilization. The study points out that sandy loam soil (the kind of marginal soil where forages are often grown) has a low water-holding capacity, limiting the moisture available to the plant. This reduces plant growth, forage quality, stocking rate and rates of gain in animals. As a result, there may be a limited benefit to fertilize and less incentive to do so.

Even if you do fertilize forages to increase yields, you need sound economic reasons for doing it. Bergen points out higher yields do not necessarily translate into lower costs or increased profits. The profitability of fertilizing forage crops depends on the cost of fertilizer and the price of hay.

“You can double your yield and increase your carrying capacity in the number of bales. But if it costs you $500 to double that yield and that doubled yield is worth only $250, it just doesn’t make sense,” says Bergen.

For that reason, it’s important to know the per-unit cost of production for hay (e.g. $/tonne) to determine which is the more economical choice: fertilizing hay or just buying it.

Keeping fertilizer at home

The trick is to get nutrients on forage land in a cost-effective way to improve forage productivity, other than adding chemical fertilizer or composted manure. Bergen lists several options for achieving that.

One option is to use in-field winter feeding systems such as bale grazing. Bergen says bale grazing kills two birds with one stone. First, when cattle graze bales during the winter, they deposit fertilizer on the field in the form of manure. Second, the bales cattle do not eat stay on the ground and become another soil nutrient. Together, these practices end up leaving more nutrients on the land than it had to begin with, thus improving soil fertility. An added benefit is that bale grazing reduces winter feeding costs because producers are not always hauling in feed.

Another option is to mix legumes (usually alfalfa) with grasses in a stand. The study notes that properly inoculated alfalfa fixes nitrogen from the atmosphere. As a result, additional N is not needed to increase dry matter yield and protein content. In this way, adding alfalfa to the mix increases productivity without the extra cost of fertilizer. It also reduces the risk of bloat because animals are not grazing straight alfalfa.

The practice seems to be catching on. It’s estimated the area of alfalfa and alfalfa mixes as a percentage of total tame hay production increased from 44 per cent in 1971 to 66 per cent in 2011.

Bergen acknowledges it’s hard to measure how much soil fertility practices are improving. But BCRC offers webinars on the subject and is starting to conduct followup surveys with participants to measure the take-up of its recommendations.

More information is available on the BCRC website at www.beefresearch.ca.

This article was originally published in the 2017 Forage & Grassland Guide.

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