Nitrogen Fertilizer Management of Malting Barley: Impacts of Crop and Fertilizer Nitrogen Prices
(Prairie Provinces and Northern Great Plains States)
By Adrian Johnston, Scott Murrell, and Cynthia Grant1
Malting barley demands a premium price over feed barley most years, increasing its appeal as a diversification crop in the northern Great Plains states and the Prairie Provinces. The demand for malting barley seems to be ever increasing in an attempt to meet the growing appetite for beer consumption around the globe. The warm, dry conditions characteristic of the northern Great Plains provides an ideal environment for growing a malt barley with grain of uniform size that is free of disease.
Nitrogen (N) management of malting barley requires careful attention. On soils with low N supplies, malting barley responds well to N fertilizer, exhibiting increases in yield and protein content. However, too much nitrogen can increase protein beyond levels acceptable to the malting industry’s standards. Excessive grain protein lengthens steeping times, makes germination more erratic, and creates undesirable qualities in malt. Besides over-application of N, excessively high grain protein levels can also arise from low rainfall and high temperatures after anthesis. Therefore, malting barley growers must address both management and environmental uncertainties to produce profitable crops.
Currently, farmers are faced with higher N prices. Fertilizer N prices are impacted by natural gas prices since natural gas represents a major portion of the production costs of fertilizer N. Periodically, the price of natural gas rises with demand, increasing the price for fertilizer N. This brings up the question: How does the price of fertilizer N influence the optimum rate of N for malting barley?
A data set developed by Agriculture and Agri-Food Canada in Brandon, Manitoba, was selected to help evaluate N price impacts on optimum N rate decisions. During the three-year period of 1986 to 1988, a series of fertilizer N rate response trials were conducted at three different locations each year in southern Manitoba. On completion, the trials were divided into groups based on growing conditions. Sites with grain yields between 35 and 50 bu/A were considered together, while those with yields between 50 and 80 bu/A were grouped together. Soil test N levels averaged 48 lb N/A (range 41-60) at the low yielding sites, while the average was 37 lb N/A (range 33-46) at the high yielding trials. The impact of varying crop price and fertilizer N cost was used to evaluate the change in N rate required to optimize economic return (N rate producing no less than $1 crop return for every $1 invested in fertilizer N).
The impact of yield potential (low vs. high yielding sites) had a major influence on the optimum N rate selected, especially at low barley prices (Table 1). These low yielding sites are characterized by very small increases in grain yield with increasing N rate. It is obvious that when yield potential is low, and barley price is low, increasing N prices have a major impact on the optimum N rate. However, barley yields in the 50 to 80 bu/A range reduced dramatically the impact of fertilizer N price changes on optimum N rate. Increasing N price by 50% ($0.20 to $0.30/lb N) reduced the optimum N rate by only 7 to 10 lb N/A using the barley price examples shown in Table 1. These results clearly illustrate the need for careful assessment of stored soil water and regional precipitation probabilities, before making your crop selection.
Remember to use all of the available tools when making N management decisions in semiarid environments. These include:
Use soil test information to provide a good estimate of soil residual nitrate-N levels. Better characterizing nitrate levels in areas of fields provides better chances of managing fertilizer N at appropriate rates.
Manage for low grain protein (<12% in some areas, 13-13.5% in others). Production in low yielding conditions is more likely to result in high grain protein and failure to get the sample accepted for malt grade.
Consider low protein varieties. Varieties with lower protein contents can provide greater flexibility in N management and withstand more marginal environments while still meeting protein standards. Low protein traits must be considered along with other variety selection options, such as resistance to diseases.
Avoid areas with high residual nitrate levels. In areas where there has been drought the previous year, N is likely to have accumulated in the soil. This will increase the potential of soil residual N increasing grain protein and reducing the opportunity to capture malting grade.
Pay close attention to all fertility needs. Increasing your chances of capturing a malting barley grade often means paying careful attention to balanced fertilization. Early seeded barley has been shown to benefit from starter potassium (K) fertilizer, increasing yield and kernel plumpness while minimizing seedling diseases. Good phosphorus (P) nutrition is critical to uniform maturity of malting barley, improving the chances of meeting the consistent kernel size desirable for malting grade.
Source: Grant, C.A., L.E. Gauer, D.T. Gehl, and L.D. Bailey. 1991. Yield response of semidwarf and conventional heiht barley cultivars to nitrogen fertilization under varying moisture conditions. Can. J. Plant Sci. 71: 361-371.
1Dr. Johnston is PPI Western Canada Regional Director, e-mail: ajohnston@ppi-ppic.org.
Dr. Murrell is PPI Northcentral Regional Director, email: smurrell@ppi-far.org.
Dr. Grant is a research scientist with Agriculture and Agri-Food Canada.
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