Every season, barley growers lose a lot of sleep over whether their crop will make malting. But plant scientists say increasing your odds of success is possible, it just takes some extra attention and management.
It’s tempting to delay seeding barley because it tends to mature faster than wheat or canola, but research now suggests that seeding barley later reduces the likelihood of barley being accepted for malt. Studies at eight locations from the northern Peace region of Alberta and B.C. to Brandon, Man., found early seeding generally contributed to higher yields, lower protein levels and better quality malt.
“The earlier seeding improved friability (the ease with which a material is crumbled, pulverized or reduced to a powder) and reduced beta-glucan levels,” says John O’Donovan, research scientist with Agriculture and Agri-Food Canada (AAFC) at Lacombe, Alta.
Beta-glucan is a constituent of malt barley that can cause filtration problems for brewers if levels are too high.
BUMP SEEDING RATES
Maltsters favour plump seeds, which are a good indication of high starch levels needed to make malt. Many farmers have tried seeding at lower rates in order to produce plumper barley kernels. The catch, however, is that lower seeding rates can result in higher protein levels and less uniformity of the kernels, both of which are highly undesirable from a malting perspective.
During the extensive barley trials conducted by O’Donovan and others, they found that a seeding rate of 300 seeds per square meter seemed to be optimum for malt barley production.
“We found that if you went over the 300 seeds per square meter, there was an increased risk of reduced yields and unacceptable plumpness,” he says. “So we feel 300 seeds per square meter is a good target to aim for.” O’Donovan is reluctant to convert that figure into bushels per acre because different barley varieties have different seed sizes, which is why they went with the 300 seeds per square meter figure.
Higher seeding rate also improved other malting qualities, such as lower protein levels, better friability and reduced beta-glucan. There was also a big effect on end-use malt quality.
“When we malted the barley we found that the malt quality was much better because of the uniform kernel size. It germinated better and more uniformly resulting in better quality malt,” says Michael Edney, program manager of Applied Barley Research at the Canadian Grain Commission.
THE RIGHT BALANCE OF FERTILITY
Choosing fertilizing rates for malt barley can be a tough balance, as too much nitrogen results in too high protein levels. If they rise above 12.5 per cent, the barley will not be accepted by maltsters. On the other hand, the crop needs nitrogen to grow. So where is the happy medium and how do you determine it?
In the field trials, all of the nitrogen was applied in the spring and to the side of the seed using a no-till system. Five rates were applied from zero to 107 lb N/ac. An initial surprise for the scientists was that at some of the sites there was a reduction in plant stands as they increased the nitrogen rate.
“Very little fertilizer was put down with the seed, so we were a bit surprised that banding the nitrogen caused some barley seedling mortality,” says O’Donovan.
Less surprising was the increase in protein levels as the nitrogen fertilizer rates were increased and, in a lot of situations, the limit for malt was exceeded.
Why do protein levels matter so much? More protein in a barley kernel makes it more difficult to take up water and get good water distribution throughout the kernel during the malting process, says Edney. As a result, the cell walls in the endosperm do not break down adequately, which leads to higher levels of beta-glucan, the main constituent of endosperm cell walls. Higher beta-glucan levels are undesirable because they lead to problems in the brewery with lautering and beer filtration. Also, as the cell walls break down, the endosperm becomes more friable (not so hard), so friability goes down with higher N rates.
They also found that increasing the nitrogen rate caused more lodging, another undesirable quality for malt. “We have not done a lot of comparisons of lodging to quality yet but a quick comparison showed the barley colour was less bright as the N rate increased,” says Edney.
Increasing nitrogen also prolonged maturity, which could be very bad news in the event of an early frost.
“Nitrogen is really a bit of a conundrum,” says O’Donovan. “It’s great for increasing yield, but every other aspect of malt barley production is negatively affected by nitrogen.”
So just what is the optimum nitrogen level that malt barley producers should aim for? The answer, as yet, isn’t clear, admits O’Donovan.
“We still have to do an economic analysis on the study,” he says, “and that will better indicate to us what level of nitrogen a farmer may use to have a good possibility of making malt quality without impacting yield to the point where the grower is going to lose money.”
Another component of the malt barley research involves technology that, although not exactly new, hasn’t been widely adopted in Canada yet. Guy Lafond, a research scientist with AAFC at Indian Head, Sask., has been looking at nitrogen use efficiency using an optical sensor that determines the non-difference vegetative index (NDVI). The Green Seeker optical sensors emit light in two very specific wavelengths and then measure the reflectance of the crop canopy to determine NDVI. This provides an estimate of the crop biomass.
“If you have a lot of biomass, you have a higher NDVI but it also means that in order to support that biomass you need more nutrients because there is just more there,” says Lafond “What we are doing is developing a relationship between NDVI and final grain yield.”
The sensor is generally used at the five-to six-leaf stage.
“There is a good correlation between the biomass estimated with the optical sensor at that stage and the final grain yield,” says Lafond.
So how is this being evaluated for making malt? During seeding, the farmer will apply nitrogen at the usual rate and then put down a nitrogen-rich strip somewhere in the field that may be 1.5 to two times the rate used in the rest of the field. That creates an upper limit control. When he goes back into his field to spray, he has three sensors on either side of his sprayer, so he can go to the N-rich strip and drive the border — leaving three sensors on the N-rich strip and three sensors on the field beside it. The Green Seeker compares the two strips, does some calculations and from there the farmer determines whether it is worthwhile to add more N. But the decision is still with the farmer.
“If there’s quite a bit of difference, and based on growing conditions, he will have more confidence that he can capture more yield by adding more N,” says Lafond.
The Green Seeker system automatically detects the areas where more N is required and calculates and applies the correct amount in real time.
The challenge remains, particularly for malt barley growers, of balancing yield against increased protein levels. Lafond says in this case it might be advisable to use a lower rate of N than your target rate so you can compare it with the N-rich strip but reduce the risk of overfertilizing areas that don’t need it.
Lafond and his research team have developed equations for canola and spring wheat which allow the Green Seeker system to calculate the amount of extra fertilizer N required. They are now developing equations for use in malting barley, durum, oats, and winter wheat.
“The algorithms developed provide very good estimates of final grain yield when measured in cereals at the flag leaf stage. In many instances we can predict within about 10 per cent what the final grain yield is going to be,” says Lafond.
The ultimate goal, says Lafond, is not just to more precisely account for spatial variation (meaning variation across the field) and its source, but also temporal variation, meaning what happens between the harvest of one crop and the growth of the next.
“With this system, when you take readings in the crop at the end of June it is integrating everything that has happened in the soil since the previous harvest, so if we had the right conditions in the fall and the right conditions in the spring to promote crop growth and nutrient cycling it is all going to be reflected in the plant,” says Lafond. “The plant has already integrated all that information.”
The system could also be a good diagnostic tool for producers, Lafond believes, and has potential for other applications including calculating economic thresholds for fungicide application, for use with crop desiccants, and for manure management.
CONSIDER YOUR STUBBLE CHOICE
At the AAFC research station in Lacombe, Alta., Kelly Turkington has been heading up trials looking at the effects of different stubble types on malt barley production. The trials used AC Metcalfe barley on AC Metcalfe barley residue, on canola residue and on field pea residue. Nitrogen was applied on each at either 50 per cent or 100 per cent of the recommended rate for the target yield for that location (based on soil tests). The last treatment was either fungicide (Tilt) applied at the flag-leaf stage or no fungicide.
Stubble type definitely had more effect upon yield than nitrogen applications, says Turkington. “Basically going from barley on barley to barley on canola or field pea stubble gave us our biggest bump in yield, while if you look at some of the data for individual sites, in some cases, yields for both of the two fertilizer rates were very similar.”
Protein levels, conversely, were affected much more by nitrogen rates than stubble types.
“If you look at the change in protein, the largest change was associated with changing the fertility rates from 50 per cent to 100 per cent of the recommended rate,” says Turkington. “That had a significant, consistent impact on protein levels, whereas the stubble type was much less consistent. We were surprised because we were expecting to see a consistent increase in protein level with field pea stubble, but in some of the measurements we didn’t see that. And for some of the others the magnitude of any increase was certainly much lower than we observed when the nitrogen rate went from 50 per cent to 100 per cent of the recommendation.”
Instances of leaf diseases were also less on canola or field pea stubble than on barley residue. Although fungicides gave increased yield, the magnitude of that increase was quite a bit lower than the yield advantage observed in changing stubble types from barley to canola or field pea.
So it appears that the benefits of growing barley on pulse stubble in terms of disease management and also potential water availability would definitely outweigh the risks of higher protein, which Turkington feels can be managed by fine tuning individual fertility programs. Canola also provides a good break crop to help with disease management and increase malt barley yields. Hopefully as more results from the research are analyzed, data will come forward to help producers do just that.
Nitrogen increases yield, but every other aspect of malt barley production is negatively affected by it