Fertility and Nutrients
Does feed barley really require more N than malt?
By Bruce Barker
Research shows the most economic rate of N for feed is often not higher than it is for malt.
The general recommendation of applying more nitrogen (N) on feed varieties has not been supported by recent studies. Malt producers are usually more prudent with N because too much may result in excessive protein (above 12.5 per cent) and rejection by maltsters.
“Excessive grain protein in malt barley is not desirable as it results in cloudy beer, and no one wants that,” says research assistant Heather Sorestad with the East Central Research Foundation (ECRF) and Parkland College in Yorkton, Sask.
To compare the N management between feed and malt barley, Sorestad and ECRF/Parkland College research manager Mike Hall partnered with the seven other Agriculture Applied Research Management (AgriARM) foundations across Saskatchewan in Scott, Yorkton, Redvers, Indian Head, Melfort, Prince Albert, Outlook and Swift Current. The research was conducted from 2017 through 2019, with three locations in 2017, seven in 2018 and eight locations in 2019. It was financially supported by Saskatchewan Agriculture’s ADOPT program and SaskBarley Development Commission.
Sorestad says the Saskatchewan Crop Planning Guide reinforces recommendations to apply more N to feed barley. It assumes producers in the Black soil zone apply 99 pounds of nitrogen per acre (lbs. N/ac) to achieve a 93 bushel per acre (bu/ac) crop of feed barley. In contrast, the guide assumes only 81 lbs. N/ac are applied to achieve 76 bu/ac of malt barley.
High yield AND low protein
In each of the three years of the AgriARM research, the response to N fertilizer of high-yielding CDC Austenson feed barley was compared to a malt barley variety. In 2017, AC Metcalf malt barley was grown at three AgriARM locations, and N rates of 40, 80 and 120 lbs./ac were applied. In 2018, CDC Bow malt barley was grown at seven locations with 50, 75 and 100 lbs. N/ac. In 2019, CDC Austenson was compared to AAC Synergy with soil plus fertilizer N at 80, 120 and 160 lbs./ac.
The Saskatchewan Varieties of Grain Crops 2019 uses AC Metcalf as the check variety for comparative purposes with other malt and feed varieties. CDC Bow malt barley yields 111 per cent of AC Metcalf, while AAC Synergy yields 118 per cent. CDC Austenson feed barley is rated at 118 per cent of AC Metcalf in Areas 1 and 2, and 121 per cent in Areas 3 and 4, similar to AAC Synergy malt barley.In total, 18 location years were analyzed, but some trials were non-responsive to fertilizer N. Yield response curves were developed for each barley variety; malt barley protein content was also assessed. The most economical rate of N for feed and malt barley was calculated at the point where one dollar per acre of N applied will return one dollar of revenue. This calculation assumed N at 50 cents per pound and prices of $3.70 per bushel for feed and $4.68 per bushel for malt.
Overall, the yield response curves to N were similar between feed and malt barley varieties. The most economical rate of N varied by year and variety. Environment played a large role in protein content, with higher protein content in drier locations. For example, in 2018 in Scott, the yield of CDC Bow malt barley was 51 bu/ac at the lowest N rate of 50 lbs./ac, but the protein was already at 12.9 per cent – usually too high to be accepted by maltsters.
Conversely, at sites with high yield, protein content was lower than 12.5 per cent at the most economical N rates. Results from Scott in 2019 found that the most economical soil plus fertilizer N was 155 lbs./ac, with a yield of close to 100 bu/ac and protein content less than 12.5 per cent. The most economical rate for CDC Austenson was 123 lbs. N with a similar yield. In Yorkton in 2019, both CDC Austenson and AAC Synergy achieved very high yields of more than 140 bu/ac at a soil plus fertilizer N rate of at least 160 lbs., while protein content remained below 12 per cent.
Overall, three site-years found the most economical rate of N for malt and barley differed only slightly. Two site-years showed the most economic rate of N was substantially higher for malt than feed barley. However, there was one site-year where the most economical rate for malt was much lower due to protein issues. In two trials, comparisons were not possible because the yield response was quite steep for both varieties, with the most economic rate of N well beyond the rates investigated in the study.
Hall says there wasn’t a lot of evidence to suggest the most economic rate of N for feed barley is higher than malt, even if the price for malt and feed were the same. It didn’t matter if the comparison was with a high-yielding or low-yielding malt variety because their yield responses to N were both similar to feed. However, he says that the overall economics of the low and high-yielding malt varieties aren’t the same. A low-yielding malt variety like AC Metcalf will generate less income compared to the higher yielding AAC Synergy, assuming both are accepted for malt.
“In fact, since AAC Synergy yields as well as CDC Austenson, there may be less reason to grow a feed variety. I should add that the bushel weight for CDC Austenson averaged 50.4 lbs. per Winchester bushel in our study, which was better than 48.6 lbs. per Winchester bushel for AAC Synergy. The goal is to maintain bushel weights above 48 lbs. per Winchester bushel for feed barley,” Hall says.
Hall cautions that malt barley growers should check with their maltsters to ensure that they are contracting AAC Synergy or other malt barley varieties. “I’m not going to be bold enough to say you should be applying more N to your malt barley. The proper rate is something you’ll have to determine based on your past experiences and anticipated environmental conditions,” Hall says. “However, I will suggest that if your malt barley protein is above 12 per cent, then feed barley in that same field would not have benefited economically from a rate of N higher than what you applied to the malt.”