April 1998
Production Tips by Michael D. Peel
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Prairie Grains is the
official publication of
the Minnesota
Association of
Wheat Growers,
North Dakota Grain
Growers Association,
South Dakota Wheat,
Inc., and the
Minnesota Barley
Growers Association.
At the top of the 1998 wish list for small grain producers is a high yielding, good quality, disease free crop. This can't be guaranteed, of course, but there certainly are management practices that can improve the potential.
Maximizing yield requires the right combination of manage-ment including fertility, moisture, and favorable growing conditions. Little can be done to alter environmental conditions, but the right management practices can enhance yield and minimize disease potential.
A factor often limiting yield is fertility. The soil nutrient most limiting to achieving maximum yield is nitrogen. Nitrogen is also directly correlated with protein content in wheat and barley. Protein objectives in hard red spring wheat and malting barley are different and fertility management obviously must be handled differently. In wheat, protein above 14% can bring a premium, where as in malting barley, protein levels above 13.5% can result in a discount.
The amount of nitrogen a crop needs depends on a number of factors such as available soil nitrogen and N credit from the previous crop. Soil nitrogen should be determined in the upper two feet of the soil with a soil test. Nitrogen credits from a previous crop vary with crop; a general guide is provided in table 1. The nitrogen level recommended for both wheat and barley should be based on a final yield goal.
Research has shown that hard red spring wheat fertilized to achieve 100% of its yield potential will generally have protein above 14%. If you are consistently producing a wheat crop with protein levels below 14% you are probably not achieving your full yield potential.
The first step in calculating required nitrogen levels is determining a yield goal. Yield goals should be optimistic yet realistic. The amount of nitrogen needed to achieve a given hard red spring wheat yield is 2.5 lbs for each bushel of expected yield. The 2.5 lbs includes available soil nitrogen and any N from a previous crop credit. Therefore added nitrogen required for a wheat crop is: (2.5 x YG) - STN - PCC, where YG is the yield goal; STN is the soil test Nitrate in the top two feet of soil; and PPC is the previous crop credit.
Determining the right amount of nitrogen for a barley crop is very similar. For malting barley the nitrogen required is: 1.5 x YG STN PCC. For feed barley nitrogen levels should be a little higher (1.7 x YG STN PCC).
Other soil nutrients, such as phosphorus and potassium, can also dramatically limit yield when in short supply. NDSU Extension bulletins "Fertilizing Hard Red Spring Wheat, Durum, Winter Wheat and Rye" (SF-712); and "Fertilizing Malting and Feed Barley" (SF723); contain detailed information on fertilizer requirements.
Planting date can influence the final yield and protein content of both wheat and barley. Early planting will favor higher yield and it will improve the chance of obtaining low protein malting barley.
The likelihood of earlier planting this spring may help minimize the risks of scab. However, wheat and barley grown in the absence of the organism that causes scab has the highest potential to escape infection. Fusarium graminearum, the organism that causes scab, survives on crop residue of wheat, barley and corn. Growing wheat or barley following one of these crops will certainly increase the potential for scab infection.
A good crop rotation provides the best means of lowered potential of scab on wheat and barley. Rotations also reduce the potential of other small grains diseases including root rot, bacterial blight, net blotch, and tan spot.
When selecting crops for rotation, the ability of each crop's potential to reduce diseases and other pests such as insects and weeds should be considered. The best combinations will include both grass crops, such as wheat and barley, and broadleaf crops, such as dry beans and soybean. A good rotation will be beneficial to all the crops involved, but requires a long-term commitment to realize all the benefits.
A rotation need not be viewed as so rigid that crop substitutions are not possible. In fact, a well thought-out rotation will allow substitutions; however, an inappropriate crop/year substitution will destroy rotational advantage.
Table 2 provides information on specific crops and appropriate rotations of each. NDSU Extension bulletin "Crop Rotations For Increased Productivity" (EB-48) contains detailed information. This and other bulletins can be obtained by calling (701) 231-7882. n