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The objective when planting wheat is to establish a uniform stand of at least 25 plants per square foot with adequate fall growth for tiller development and an established root system for winter survival. Planting methods include drilling, broadcast seeding, aerial seeding, and no-tillage planting. Each has advantages and disadvantages. Choose your planting method based on planting equipment, time and labor availability, seeding costs, planting date opportunity, weather, crop usage, yield goals, and stand establishment risks associated with each method.
You can use drills for conventional tillage, reduced tillage, and no-tillage (discussed later). Conventional tillage provides a level, smooth seedbed for drilling and results in a more uniform planting depth. Reduced tillage and no-tillage planting also can work well, with proper drills and adjustments. Leaving crop residue on the soil surface protects the soil from erosion until the wheat crop becomes established and develops a cover. Most of the wheat crop in Kentucky is drill-planted in a reduced-tillage situation using a chisel plow followed by secondary tillage (disking). A heavy offset disk, however, can also provide acceptable primary tillage, depending on the amount of residue.
You can use broadcast seeding as either a planned or an emergency seeding method. This planting method involves broadcasting wheat seed on the soil surface and incorporating the seed with tillage (by disk or field cultivator). Broadcasting is a fast method of seeding wheat and is an acceptable option if corn or soybean harvest is delayed or weather delays push planting dates to the end of or beyond the optimum planting period.
You can use tillage before and/or after spreading seed; however, tillage after seeding is usually sufficient if residue is not heavy. Shallow tillage is preferred over deep tillage because it distributes seed more uniformly and improves stand establishment. Seeding into soybean residue is usually more successful than seeding into corn residue because of less residue cover, which makes incorporation of seed more uniform. With corn residue, particularly heavy residue, tillage prior to seeding is helpful. This is preferred over multiple passes or heavy tillage after seeding, which can incorporate seed too deep.
Yields of broadcast-seeded wheat are usually less than those of drill-seeded wheat. Seed placement is variable, even within a given field, and can range from seed that doesn't emerge because of being placed too deep (3 to 4 inches) to seed on the soil surface that doesn't survive because of dry soil or winter damage. As a result, plant emergence is nonuniform and can extend over a long period of time due to seed depth differences.
Stand uniformity is reduced and can vary from sparse to dense due to nonuniform seeding and incorporation. A more uniform stand can be obtained (although it is more time consuming) if the seed is applied in two passes across the field at a half seeding rate per pass, with the second pass perpendicular to the first pass.
Because plant establishment potential is reduced and seed placement is not uniform, seeding rates should be increased for broadcast seeding. Increase broadcast seeding rates by 30 percent to 35 percent over drilled seeding rates. This equates to seeding rates of 45 to 47 seeds per square foot (or approximately 2½ bushels per acre at average seed size). Soil moisture as well as the amount of crop residue and how well it is incorporated are crucial to stand establishment.
Broadcasting wheat with fertilizer is a fast way to seed after harvest. Take precautions to ensure that the seed is uniformly blended with the fertilizer and that the fertilizer-seed mixture is uniformly applied. Seed should be mixed with fertilizer as close to the time of application as possible and applied immediately after blending. Allowing the fertilizer-seed mixture to sit after blending (longer than eight hours), particularly with normal super phosphate, results in seed damage (reduced germination) and, subsequently, a poor stand.
In summary, broadcast seeding is a faster method of seeding and can save time during corn or soybean harvest. The time saved may offset some of the greater costs and potential yield loss associated with broadcast wheat. Disadvantages include variable seed depth placement and emergence, nonuniform stands, potential for reduced stands, usually lower yields, increased chances of winter injury to shallow-placed seed, and higher seed costs.
Aerial seeding is used as both an emergency and a planned seeding method. Although you might consider aerial seeding an emergency method, successful results are more likely to be achieved if you plan it. Aerial seeding is risky unless well planned. Aerial seeding involves overseeding of wheat onto the soil surface in an established summer crop (e.g., corn or soybeans) prior to harvest of that crop with no incorporation of the seed. It is a quick method of seeding wheat that saves time when other crops need to be harvested or when harvest of the summer crop is delayed because of weather or late maturity. Its success depends on the weather, stand establishment, and timing of seeding. Yields can equal those of drilled wheat or can be a complete failure.
Stand establishment is critical. Sufficient moisture is needed for germination of the surface seedings and for continued survival for root and seedling establishment. Good seedling establishment must occur prior to cold weather or winter survivability of the crop will be decreased. Aerial seeding results in plants with wheat crowns at or above the soil surface. This exposure of the wheat crown can result in winterkill if extremely cold temperatures occur.
You can seed into soybeans or corn; however, seeding into soybeans is usually more successful. Aerial seed wheat into soybeans just before leaf drop when most leaves have turned yellow so leaves provide a mulch cover and improve the environment for germination of the wheat seed. If seeding into unharvested corn, wait until vigorous growth ceases and little or no green color remains in the corn plants. Best results are achieved if aerial seeding coincides with a moist soil surface or when rainfall is anticipated so that chances of germination and seedling establishment are increased. Most planned aerial seedings are in September and early October. In Kentucky, rainfall is usually low during this period, which increases the risk for poor stands and/or results in germination extending over several weeks.
Date of planting is usually earlier with aerial-seeded wheat in order to coincide with leaf drop in soybeans or field maturity in corn. Most seedings occur prior to the optimum planting date for wheat. As a result, there is an increased risk of damage from Hessian fly, wheat spindle streak mosaic virus, take-all disease, and aphids (which transmit barley yellow dwarf virus). However, early plantings have a greater chance of success than late plantings. Better stands are usually achieved, and winter survival is usually enhanced because plants have a longer time to become established. Most aerial seeding failures occur when the seeding is used as an emergency method late in the fall. The cooler temperatures prolong germination and seedling establishment, and the smaller plants are more prone to winter damage.
Increase seeding rates for aerial-seeded wheat. Broadcasting wheat seed on top of the soil without tillage to incorporate it into the soil is risky. Stands of broadcast wheat usually have only 50 percent to 75 percent of the density and uniformity of drilled wheat. You can alleviate the risk for poor stands somewhat by increasing seeding rates 40 percent to 50 percent over those used in drill seeding. This is roughly equivalent to a seeding rate of 50 to 55 seeds per square foot (or approximately 2½ to 3 bushels per acre, depending on seed size).
In summary, seeding time, amount of seed, and timely rainfall are important for good aerial-seeded wheat establishment. Advantages of aerial-seeded wheat are earlier planting, fast seeding, possible labor and equipment savings, and early wheat growth. Disadvantages include potential for higher disease and insect incidence, little protection of the wheat crown from winter injury, higher seed costs, and weather-dependent stand establishment.
Steadily increasing in acreage in Kentucky, no-till wheat was planted on 26 percent of the wheat acreage in 1996. Advantages of no-till over conventional planting of wheat are reduced soil erosion and lower labor, machinery, and energy costs. No-till also allows for a more timely planting date when the wheat planting season is excessively wet or complicated by delayed corn and soybean harvest. On the other hand, no-till wheat can result in more uneven stands and planting depths, increased disease incidence, and reduced plant vigor. All of these can cause reduced yield in a high-yield environment. However, management changes can reduce or eliminate most of these disadvantages.
Yield comparisons from several trials show little or no difference between no-till and conventional plantings. It appears that with proper management, no-till seeded wheat yields very close or equal to conventionally seeded wheat. Trials in the 1980s at the University of Kentucky indicated equal yields. Trials over a four-year period in the 1990s indicated a yield decrease of 5 bushels per acre for no-till wheat planted behind corn. In these trials, the yield difference was mainly due to pre-existing compaction problems the first year and increased winterkill because of shallow no-till planting the fourth year. During this same time, a replicated field trial in Todd County resulted in equal yields between the two systems.
Residue management varies with the crop. Planting after soybeans is ideal; after corn, residue management is vital. Combines should have straw choppers and chaff spreaders to evenly distribute the corn residue. This is important for even depth and seed placement during drilling.
You do not need to chop corn stalks prior to planting, especially if you are planting soon after corn harvest and the bottoms of the stalks are moist and hard. However, chopping the corn stalks might reduce incidence of some diseases (head scab) and improve coulter penetration through the corn residue if enough time (two to three weeks) is allowed for the residue to dry and begin deteriorating. A rotary mower is commonly used but may have a tendency to "windrow" the residue. A flail chopper is a better tool and distributes the residue more evenly for a more uniform seeding depth. Drilling wheat at an angle to the corn stalk row is also helpful because a drill unit is not continually in a row of corn stalks.
Increase seeding rates for no-till wheat by 10 percent (35 to 40 seeds per square foot) over conventionally planted wheat due to no-till's less-than-ideal seeding conditions. This is important, particularly if there is heavy, nonuniform residue.
Fertility needs are comparable to those of conventionally planted wheat. The only difference is in nitrogen. The cool, moist condition in early spring slows early plant growth, and the surface residue can immobilize some nitrogen. The rate of nitrogen applied in the spring should be increased by 20 to 30 pounds per acre over conventionally planted wheat. If the nitrogen is split, the late winter (February) application should probably receive as much nitrogen as the March application.
Weed control in the fall is important for success and can be achieved in two ways: 1) with a contact herbicide applied just before or soon after planting and a spring herbicide to control garlic, or 2) a herbicide in late November to control both broadleaf plants and garlic (a spring herbicide may not be needed). The use of a burndown herbicide with late plantings helps control cool-season grasses, such as ryegrass or cheat, if they are present.
The impact of diseases and insects on no-till wheat is similar to the effects on conventionally planted wheat. Fungicides and insecticides to control diseases and insects should be used in the same manner as with conventional tillage. There is no evidence to indicate that diseases or insects are increased by no-tillage. Some states feel head scab could be an increased problem, but this has not been documented in Kentucky. Chopping the corn stalks might help reduce the potential for head scab.
If soil compaction exists in the field, it should be alleviated before wheat is no-tilled. This can be accomplished by using subsoiling equipment. Some types leave most of the residue on the surface and other types cause considerable soil disturbance which would require additional tillage. Compaction causes the soil to waterlog easily, puts the wheat under stress, and can reduce the yield. Compaction can be detected by a penetrometer or probe. Once the compaction is remedied and most crops are no-tilled, the field usually will remain free of compaction.
Winterkill is a problem about every four or five years in Kentucky. It can be more pronounced in no-till plantings
if the planting depth is ½ inch or less. To remove this increased risk, use the proper planting methods and adjustments
to plant 1 to 1½ inches deep. Also, be sure to plant a winterhardy variety.