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The effect of agronomic practices on malt quality parameters

Researchers take unique approach of developing an agronomic package that goes beyond malt barley quality to also optimize the final malt extract quality.

October 9, 2008  By Donna Fleury

Researchers take unique approach of developing an agronomic package that goes beyond malt barley quality to also optimize the final malt extract quality.

John O'Donovan describes the malt barley research at Lacombe's summer tour.
Photo by Bruce Barker

Previous research has shown that agronomic practices do have an impact on quality factors such as test weight, protein level and seed plumpness of malt barley grain. However, a new research study goes beyond the effects on malt barley quality and takes a look at the effects of agronomic practices on final malt extract quality at the end product stage.

Led by Dr. John O’Donovan, research scientist at the Agriculture and Agri-Food Canada (AAFC) Lacombe Research Station, this new study was initiated in 2005 and will run until 2008. “We’re working with Dr. Mike Edney of the Canadian Grain Commission to try to tie the effects of agronomic practices on some of the other malt barley quality parameters of the finished malt extract,” explains O’Donovan. Some of the finished malt quality parameters include uniformity or homogeneity of endosperm modification, friability and beta glucan levels.

There are three agronomic components to the study looking at how to improve malt extract quality. Two of the components include a comparison of five different seeding rates and five different nitrogen rates, while a third component is assessing the effects of stubble type on disease levels, the use of fungicides and the interaction with nitrogen fertilizer. The studies are being conducted at eight locations across the prairies, including four in Alberta, three in Saskatchewan and one in Manitoba. Conducting the studies across these various locations covers all of the different soil zones and climatic conditions for malt barley. The research is funded by the Alberta Barley Commission, Canadian Wheat Board, Rahr Malting and the AAFC Matching Investment Initiative.

“We selected two varieties of malt barley to work with, each having very different characteristics,” says O’Donovan. The two varieties are AC Metcalfe and CDC Copeland, both two-row varieties. These varieties differ in their diastatic power, which is basically the level of starch degrading enzymes they possess and their ability to convert starch to sugar. Although both varieties are in the acceptable range of diastatic power, AC Metcalfe is at the higher end, while CDC Copeland is at the lower end.

O’Donovan emphasizes that the objective is not to compare the performance of the two varieties, rather the objective is to try to develop agronomic practices to improve the quality of both varieties, and to identify a range of agronomic practices thatbest suit different varieties. “We know one universal practice will not suit every variety, so by identifying the range of practices for two quite different varieties, it should enable us to provide good guidelines for growers for several varieties.”

The results so far are very preliminary, with some data from 2005 and 2006 analyzed, but the 2007 results are not yet available. “We have some general observations at this point, but we won’t be able to provide any recommendations until we have completed the study,” says O’Donovan. “Generally, we are finding that the seeding rate is definitely having an impact on some of the quality parameters.”

Phoenix Micromaltings, which was used to malt all the barley samples for the research project.
Photo courtesy of K. Turkington, AAFC

As the seeding rate increases, the variability of the seed lot decreases, and both the malt barley grain and malt extract become more uniform. The homogeneity of malt modification improves, as does the friability of the malt, when the seeding rate is increased. “Another positive response is that, as seeding rates increase, there is a trend towards reduced beta glucan levels, which also improves malt quality.” Increased seeding rates also tended to shorten the maturity period, which can be significant for malt barley quality.

One expected trend of increased seeding rates is a reduction in kernel plumpness. “Although we usually think of this as a bad thing, the improvement in other quality parameters as a result of increased seeding rates may outweigh any reduction in plumpness,” explains O’Donovan. In a few cases, especially in the Peace Region at Beaverlodge, researchers did see a decrease in yield at too high seeding rates. “We did see a bit of a decrease in yield at Beaverlodge when we got up around 400 seeds per square metre. Our preliminary suggestion, so far, would be a seeding rate of about 300 seeds per square metre to optimize yield and quality of both varieties.”

With the fertilizer component, the preliminary results show that without exception, yields increased as fertilizer rates increased from zero to 120 kilograms per hectare of nitrogen (N). “However, we didn’t necessarily get a corresponding increase in quality at higher N levels,” says O’Donovan. At the higher rates of N, the days to maturity increased by two or three days. As well, some of the malt extract quality parameters, such as homogeneity and friability decreased at higher N rates.

“We aren’t suggesting reducing N too much, but we want to strike a balance between N rates, seeding rates, variety, stubble type and fungicides to come up with the best package that would most likely give growers the best chance of having barley accepted as malt,” says O’Donovan. “We expect to be able to provide that package at the end of this study.”

Dr. Mike Edney, program manager, Applied Barley Research with the Canadian Grain Commission, is conducting the testing on the malt barley grain and the resulting malt extract quality parameters. “Looking at the malting quality of the end product, as affected by agronomic practices, is a unique direction and we’re excited about that,” he says. “We’re conducting all of the standard malting and malt analysis, plus doing some unique tests that aren’t routinely used such as homogeneity of both the grain and the malt.”

One of the tests uses equipment called the Single Kernel Characterization System (SKCS), which measures and calculates the mean weight, diameter, hardness and moisture of 500 individual kernels per barley sample. “The system then calculates the average and standard deviation, which helps us determine the variability of the sample with respect to those four variables,” explains Edney. “We’re about halfway through the study and we are finding some promising differences. Some standard deviations were lower with increased seeding rate, indicating a more homogeneous sample, however we want to see results from the rest of the study before making specific recommendations.” To-date, about 300 samples have been malted and analyzed for quality from 2005 and 2006, while the 2007 samples have not yet been analyzed.

“So far the results are supporting some of the work previously done by O’Donovan, which promotes higher seeding rates for different agronomic reasons,” says Edney. Seeding date also seems to have an impact, with earlier seeding resulting in better malt quality. “We’re also seeing some differences in varieties, with one appearing to be less susceptible to the variation in N fertilizer rates.” With one variety, higher N levels decreased malt friability, while friability of the other variety remained constant at different N levels.

Both O’Donovan and Edney are excited about the potential results of the study, and the ability to provide the best agronomic package for achieving quality malt barley and finished malt extract. “By using the two varieties, we’re getting a sense of the variability that exists between varieties and that helps us to develop the range of guidelines to address the variability of varieties. This information will also be of interest to barley breeders who can address this variability in future breeding programs. Results of the study will be available in early 2009.

Role of crop residues on disease risk and control
A third component of the research, initiated in 2006, is assessing the influence of crop residue and rotations on disease risk and the interaction with fungicides and N fertilizer. “Although previous research has looked at the impact of diseases and fungicide use on malt barley factors such as yield, kernel size and plumpness, this is the first study to go one step farther and look at the factors related to malt extract quality, such as seed homogeneity,” explains lead, Dr. Kelly Turkington, research scientist at the AAFC Lacombe Research Station.

Three crop residue types are being compared, including AC Metcalfe barley grown on AC Metcalfe barley, AC Metcalfe barley grown on field pea residue and AC Metcalfe barley grown on canola residue. “We’re looking at the role of crop residue in terms of how it influences disease risk, and whether or not fungicides are required to mitigate disease effects,” explains Turkington. Researchers have selected Tilt, an established broad spectrum fungicide for barley, to use in the treatments. “We’re also looking at the impact of crop residue in terms of N fertility requirements, comparing 100 percent of soil test recommendations for N and 50 percent of soil test recommendations for N.”

Barley diseases will be measured using a leaf rating measurement. Diseases will vary by location, but researchers expect to find scald, two types of net blotch including net form net blotch and spot form net blotch, as well as other leaf spot diseases. “We will be collecting leaf samples at two growth stages and assessing the percent leaf area diseased for each crop, and the severity and incidence of the various diseases,” explains Turkington.

The first samples will be collected at the flag leaf emergence stage, which is typically the last week of June or first week of July. “This stage is the key time in terms of barley to scout for leaf diseases and to make a decision of whether or not to spray.” Samples will also be collected at the late milk or early dough stage, typically in the third week of July to the first week of August, depending on the year. This is the stage where treatments are compared and the impact on yield can be determined.

Turkington is hoping this added information will lead to the development of better tools for growers in terms of assessing the risk of leaf diseases in barley crops. “We hope to be able to relate what we find at flag leaf emergence to what we see later on in the season. This information should help us develop a good rule of thumb for fungicide application and whether or not one is required.”

Turkington also expects the results will show the impact of crop rotation, disease levels and fungicide use on malt barley and malt extract quality parameters, including homogeneity. “This information will become part of the overall agronomic package that will help growers achieve top malt barley quality and final malt extract quality.” Results are expected to be available at the end of 2009 crop year.


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