Many questions still surround the field management of distilling barley. In 2017, there were numerous examples of fields which had been managed using recommendations tailored for distilling barley but failing to get across the line and make the necessary protein band.
The risk of rejection through not meeting contracted protein bands for distilling grain and possibly incurring a yield hit remains a concern among growers.
For these reasons, one of the presentations at this year’s Teagasc malting barley conference sought to address these issues to help growers to better understand how to maximise the chances of growing barley to pass for distilling.
Malting barley for Boortmalt is produced in two protein bands. Brewing requires protein between 9.3% and 10.8% while distilling, which traditionally meant grain protein levels of under 8.8%, has now been raised to 9.3%.
The question remains whether meeting the protein target for distilling barley is as simple as cutting back on nitrogen (N) rates as some would believe.
Dr Richie Hackett from Teagasc outlined the complexity and unpredictability of predicating protein content in response to applied N on different sites and in different seasons. This in turn makes N recommendations tricky.
In order to understand this relationship and maximise growers’ chances of manipulating the outcome, it is important to understand what determines percentage protein.
Determining percentage protein
Percentage protein is determined by the starch-to-protein ratio in grain. Starch essentially comes from photosynthesis. When a growing crop captures light, it converts that light energy into sugars which are transported to grain sites and converted into starch.
Protein on the other hand is determined by nitrogen intake by the plant, which can be supplied from chemical fertiliser, manure or soil nitrogen.
Crop nitrogen intake is not directly linked to growth or yield and the more N available to the crop equals more protein produced per hectare. If yield isn’t increasing, then protein levels will be higher per hectare.
As yield increases, so too does grain starch level. As starch levels increase, this will dilute protein with yield to give lower protein.
Crop husbandry
You have a lot of control, but not full control, over some of the factors which determine percentage protein, explained Richie.
As starch content is dictated by solar radiation interception, a thick canopy is essential. This is where crop husbandry factors will have a large part to play. There needs to be good establishment and tillering in order to maximise green leaf area production in the crop .
Sowing early has a marked effect on keeping protein levels down by increasing yield. Teagasc research has consistently found this when comparing early March drilling to early April drilling. However, seedbed condition is crucial.
Canopy protection also has an important role to play, as any factor which limits yield potential is likely to limit the dilution effect. Liz Glynn discussed disease control challenge and strategies.
The current resistance issues with ramularia leaf spot pose a significant challenge. We were reminded of the importance of using the chemical diversity available, but particularly including chlorothalonil in a ramularia control programme for spring malting barley.
Richie explained the importance of correct fertility when chasing yield to dilute proteins. Referring to Teagasc trial work, he explained that a low phosphorus (P) site gave significant decrease in protein when the first 10kg P/ha was applied and a gradual drop in percentage from further increases in P applications.
Nitrogen management
It is very difficult to predict an exact N rate which will produce low protein. Rates will vary between fields and seasons due to a range of differences in yield, soil N availability and fertiliser efficacy.
Over a series of trials across a number of years, Richie applied 150kg N/ha each year to spring malting barley. The protein content varied between 7.7% and 13.2%. This serves to show that there is no one-size-fits-all approach to determining the optimum N rates.
In the same set of trials, the research found that 62% of crops which received 90kg N/ha met the under 8.8% protein band, whereas this percentage dropped to 29% when 150kg was applied.
This proportion increased to 86% when 90kg N/ha was applied to target the under 9.3% protein band and dropped to 33% when 150kg/ha was applied. At low levels of N, the likelihood of grain passing for distilling is much higher, but yield penalties are likely when using below optimum N rates.
Using these responses, it was extrapolated that grain protein increases by 0.2 percentage point for every 10kg N/ha.
The unpredictability of soil N availability adds to the challenge. It is very difficult to accurately predict the amount of soil N available at the time of sowing and released throughout the growing season.
Small variations in N released from the soil could be enough to determine whether grain meets the distilling specification or not.
The message in this case was to target land which doesn’t have a history of frequent manure application or have a heavy soil type. In a survey with commercial growers, it was found that sites which used organic manures frequently had higher protein levels.
The findings also found that the closer you got to grass in a rotation, the higher the protein percentage. The further away from the grass you got, the lower the protein percentage.
While N rate is more important than timing, this still had a potentially negative effect if judged wrong, particularly when N is applied beyond GS31.
In summary
The key message from the presentation was that anyone aiming to produce distilling-specification grain needed to target fields with a history of producing low protein levels. The aim is to manage the crop for high yield, but avoid high N availability, which means targeting well-worn fields with good fertility.
Early drilling is important, but only when ground conditions are right. Crop husbandry and fertility need to be in order so that yield potential can be maximised and protected.
Nitrogen levels should not exceed more than 120kg N/ha and lowering the rate will help increase the chances of meeting distilling specifications.
Key points
Manage a crop for high yield to maximise starch levels.Avoid fields with high soil nitrogen availability to crop.Crop husbandry and soil fertility levels need to be good.Target between 90kg and 120kg N/ha before GS31. Read more
Three new spring barley varieties recommended for 2018
Glanbia’s delivered-in grain pricing model revealed
Many questions still surround the field management of distilling barley. In 2017, there were numerous examples of fields which had been managed using recommendations tailored for distilling barley but failing to get across the line and make the necessary protein band.
The risk of rejection through not meeting contracted protein bands for distilling grain and possibly incurring a yield hit remains a concern among growers.
For these reasons, one of the presentations at this year’s Teagasc malting barley conference sought to address these issues to help growers to better understand how to maximise the chances of growing barley to pass for distilling.
Malting barley for Boortmalt is produced in two protein bands. Brewing requires protein between 9.3% and 10.8% while distilling, which traditionally meant grain protein levels of under 8.8%, has now been raised to 9.3%.
The question remains whether meeting the protein target for distilling barley is as simple as cutting back on nitrogen (N) rates as some would believe.
Dr Richie Hackett from Teagasc outlined the complexity and unpredictability of predicating protein content in response to applied N on different sites and in different seasons. This in turn makes N recommendations tricky.
In order to understand this relationship and maximise growers’ chances of manipulating the outcome, it is important to understand what determines percentage protein.
Determining percentage protein
Percentage protein is determined by the starch-to-protein ratio in grain. Starch essentially comes from photosynthesis. When a growing crop captures light, it converts that light energy into sugars which are transported to grain sites and converted into starch.
Protein on the other hand is determined by nitrogen intake by the plant, which can be supplied from chemical fertiliser, manure or soil nitrogen.
Crop nitrogen intake is not directly linked to growth or yield and the more N available to the crop equals more protein produced per hectare. If yield isn’t increasing, then protein levels will be higher per hectare.
As yield increases, so too does grain starch level. As starch levels increase, this will dilute protein with yield to give lower protein.
Crop husbandry
You have a lot of control, but not full control, over some of the factors which determine percentage protein, explained Richie.
As starch content is dictated by solar radiation interception, a thick canopy is essential. This is where crop husbandry factors will have a large part to play. There needs to be good establishment and tillering in order to maximise green leaf area production in the crop .
Sowing early has a marked effect on keeping protein levels down by increasing yield. Teagasc research has consistently found this when comparing early March drilling to early April drilling. However, seedbed condition is crucial.
Canopy protection also has an important role to play, as any factor which limits yield potential is likely to limit the dilution effect. Liz Glynn discussed disease control challenge and strategies.
The current resistance issues with ramularia leaf spot pose a significant challenge. We were reminded of the importance of using the chemical diversity available, but particularly including chlorothalonil in a ramularia control programme for spring malting barley.
Richie explained the importance of correct fertility when chasing yield to dilute proteins. Referring to Teagasc trial work, he explained that a low phosphorus (P) site gave significant decrease in protein when the first 10kg P/ha was applied and a gradual drop in percentage from further increases in P applications.
Nitrogen management
It is very difficult to predict an exact N rate which will produce low protein. Rates will vary between fields and seasons due to a range of differences in yield, soil N availability and fertiliser efficacy.
Over a series of trials across a number of years, Richie applied 150kg N/ha each year to spring malting barley. The protein content varied between 7.7% and 13.2%. This serves to show that there is no one-size-fits-all approach to determining the optimum N rates.
In the same set of trials, the research found that 62% of crops which received 90kg N/ha met the under 8.8% protein band, whereas this percentage dropped to 29% when 150kg was applied.
This proportion increased to 86% when 90kg N/ha was applied to target the under 9.3% protein band and dropped to 33% when 150kg/ha was applied. At low levels of N, the likelihood of grain passing for distilling is much higher, but yield penalties are likely when using below optimum N rates.
Using these responses, it was extrapolated that grain protein increases by 0.2 percentage point for every 10kg N/ha.
The unpredictability of soil N availability adds to the challenge. It is very difficult to accurately predict the amount of soil N available at the time of sowing and released throughout the growing season.
Small variations in N released from the soil could be enough to determine whether grain meets the distilling specification or not.
The message in this case was to target land which doesn’t have a history of frequent manure application or have a heavy soil type. In a survey with commercial growers, it was found that sites which used organic manures frequently had higher protein levels.
The findings also found that the closer you got to grass in a rotation, the higher the protein percentage. The further away from the grass you got, the lower the protein percentage.
While N rate is more important than timing, this still had a potentially negative effect if judged wrong, particularly when N is applied beyond GS31.
In summary
The key message from the presentation was that anyone aiming to produce distilling-specification grain needed to target fields with a history of producing low protein levels. The aim is to manage the crop for high yield, but avoid high N availability, which means targeting well-worn fields with good fertility.
Early drilling is important, but only when ground conditions are right. Crop husbandry and fertility need to be in order so that yield potential can be maximised and protected.
Nitrogen levels should not exceed more than 120kg N/ha and lowering the rate will help increase the chances of meeting distilling specifications.
Key points
Manage a crop for high yield to maximise starch levels.Avoid fields with high soil nitrogen availability to crop.Crop husbandry and soil fertility levels need to be good.Target between 90kg and 120kg N/ha before GS31. Read more
Three new spring barley varieties recommended for 2018
Glanbia’s delivered-in grain pricing model revealed
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