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24
Sep
2015
Planting wheat in 2015
Author: Jason Kelley, Wheat & Feed Grains Extension Agronomist

By Jason Kelley, Extension Agronomist-Wheat and Feed Grains

With the continued warm and dry weather across Arkansas, harvest of summer crops is making good progress.  The latest Arkansas Agriculture Statistics Service Crop Progress Report indicates that corn harvest is 90% complete, 57% for rice, 82% for grain sorghum, and 22% of the soybeans have been harvested.  As harvest slows down for some, many may be considering planting wheat this fall.  Below are some general discussions about getting your wheat crop off to a good start.

Previous Crop

In recent years, most of our wheat has been planted following a soybean or corn crop.  With the greatly expanded grain sorghum acreage this year in Arkansas (estimated to be nearly 500,000 acres), many have been asking, “how will planting wheat following grain sorghum impact wheat yields?”  In an on-going crop rotation study at Marianna, wheat yields were not greatly impacted by any previous crop in 2014 or 2015.   Two year average yields ranged from 70 to 73 bu/acre when wheat was planted following early-season soybean, corn, or grain sorghum.  In this study, corn and grain sorghum were harvested in August and early-season soybeans were harvested in September.  Plots were tilled soon after harvest, and wheat was then planted in late October into conventionally tilled seedbeds.  This data is consistent with most information available that does not show great differences in wheat yields when following corn, grain sorghum, or soybean.

wheattable1

*This study is supported by the Arkansas Wheat, Corn and Grain Sorghum, and Soybean Research Promotion Boards.

 

Planting Date

Proper planting date for wheat is very important for optimal yields.  Planting too early can lead to multiple problems including increased potential for freeze damage because wheat gets too big and rank during the fall and increased risks from insects including fall army worms and Hessian fly, and Barley Yellow Dwarf Virus, which is transmitted by aphids.  Recommended planting dates for Arkansas are listed below:  wheattable2

*These dates represent the ideal planting dates for Arkansas, planting earlier or later can still produce good yields, but there may be greater risks outside of these “ideal” dates.

Variety Selection

There are lots of varieties on the market that will yield well, but choosing more than one variety with different genetics and varying maturity is critical to spreading your risks out.   Varieties should be adequately tested in your area to have confidence in how they will perform and ideally, have favorable yields from 2 or more years.  Varieties should have resistance to stripe and leaf rust, as well as good resistance to lodging, good test weight, and of course have high yields.

The 2015 Wheat Update publication is a summary of the Arkansas Wheat Variety Testing Program, and contains current variety disease ratings, agronomic data including test weight, lodging, and relative maturity, and multi-year yield data.  The 2015 Wheat Update can be found at the following link:

http://www.uaex.edu/farm-ranch/crops-commercial-horticulture/wheat/

The full report of the 2015 Arkansas Wheat Variety Testing program can be found at:

http://arkansasvarietytesting.com/home/wheat/

One key production practice to consider is to plant late-maturing varieties first and early-maturing varieties later in the planting season.  Yes, sometimes we get all of our wheat planted within one week and this might not make that much difference.  However, the early-maturing varieties tend to have less of a vernilization requirement and can begin to joint very early in the spring which greatly increases risk of freeze damage, so planting the early-maturing varieties last makes sense.  In past years we have seen some of the early-maturing varieties that were planted too early, get tall and rank in the fall which led to freeze damage problems later on.

Seeding Rates

Seeding rates can vary considerably, depending on planting date, quality of the seedbed, and whether wheat is drilled or broadcast seeded.  Using a grain drill allows for more precise seed placement and generally allows for a lower seeding rate.  Broadcasting wheat allows you to cover many acres quickly.  I prefer to drill wheat but concede that weather sometimes pushes us to get things done quickly to beat an incoming rain.

Recommended seeding rates for drilled wheat planted within recommended planting dates is 26 seeds per square foot.  The pounds per acre of seed planted to achieve 26 seeds per square foot can vary considerably with seed size, (See Tables 1 and 2) but with a normal seed size, this would be approximately 90 pounds of seed/acre (assuming you had good quality seed).    Figure 1 below

Figure 1.  Impact of Seeding Rate of Drilled Wheat on Yield in Arkansas in 12 Trials

Figure 1. Impact of Seeding Rate of Drilled Wheat on Yield in Arkansas in 12 Trials

shows a summary of 12 trials conducted in Arkansas over the last few years evaluating seeding rate response of drilled wheat when planted in October.  Planting more than 26 seeds per square on sands or silt loams did not increase or decrease yields, while on clay soils, a slightly higher seeding rate was needed to achieve maximum yield. A higher seeding rate on the clay soil was likely needed to compensate for a rougher seedbed and/or potentially a lack of tillering.

 

Table 1 below shows the number of seeds per foot of drill row to accomplish a desired seeding rate.  For example, a seeding rate of 30 seeds per square foot using a grain drill with 7.5 inch row spacing would, you would need 19 seeds per foot of drill row to achieve 30 seeds per square foot. wheattable4

 

 

Table 2 below illustrates how seed size greatly impacts the pounds of seed planted.  In the example of planting 30 seeds per square foot with a large seed of 10,000 seeds per pound, we would need 131 pounds of seed per acre to accomplish 30 seeds per square foot.  If we had a small seeded variety with 18,000 seeds per pound, we would only need 73 pounds of seed per acre, a 58 pound difference in seeding rate.  Considering seed size can help prevent you from planting too many or too few seeds and maximize yields and profits.wheattable5

If we are planting later in the planting window (generally November), planting into a rough seedbed, or planting no-till, increasing seeding rates 10-20% or more would be justified.  Broadcast seeding generally takes higher rates of seed to obtain stands since the seed is placed at varying depths with incorporation (some too deep, some on top of the soil).  Having a good firm seedbed prior to spreading seed is important.  Many producers are having good results broadcasting seed and then shallowly incorporating using a harrow, roller, or field cultivator with rolling baskets.  Using a disk to incorporate often buries much of the seed too deep and can result in poor stands.   How the seed is incorporated makes all the difference on how successful broadcast planting is.

Land and Seedbed Preparation

Having adequate surface water drainage is critical for maximizing wheat yields in the Mid-South.  Adding drain furrows after planting to allow excess water to drain is very important.  In recent years there has been an increasing amount of wheat planted on raised beds.  This helps facilitate water drainage and also allows for quicker plant back of double crop soybeans after wheat harvest.  Bedded wheat will likely work best on precision leveled fields that have a uniform grade so water can drain off adequately.   In large block trials that we have been conducting over the last few years, comparing bedded vs flat planted wheat, yields were similar.    There are many ways of planting wheat on beds, but the wider the bed the better the wheat will likely be.  However, beds wider than 60 inches may be too wide for maximum soybean yields since furrow irrigation water may not fully soak into a 60 inch or wider bed.  Below are examples of production systems currently being utilized by Arkansas wheat producers and with proper management, all are producing good wheat yields.

Figure 2. Drilled, planted on flat ground with drain furrows

Figure 2. Drilled, planted on flat ground with drain furrows

 

Figure 3.  60 inch wide beds, drilled wheat

Figure 3. 60 inch wide beds, drilled wheat

On bedded wheat, one of the issues we have seen is that we still have to get the water off the field.  A drain furrow across the beds at the bottom of the field will allow water to leave the field.

Whichever system you use to plant wheat, (drilled, broadcast, flat, or bedded) taking the time to get things right is the most important item to consider.  Once the wheat is planted, you don’t have a chance to do it again.

Figure 4.  38 inch wide beds, broadcast, then roller bedded.

Figure 4. 38 inch wide beds, broadcast, then roller bedded

Figure 5.  38 inch wide beds, broadcast and hipped.

Figure 5. 38 inch wide beds, broadcast and hipped

Fall Fertilization

Fall nitrogen is typically not recommended unless planting wheat following rice or if planting later than the recommended dates (November).   In the past, a small amount of nitrogen was recommended at planting following corn or grain sorghum, but data did not show a consistent yield benefit.   If soil sample analysis shows a need for phosphorus and DAP (18-46-0) is used, the nitrogen with that application would be sufficient for any fall needs.  Having adequate phosphorus is critical for maximizing wheat yields.  The current Wheat Fertility Recommendations can be found in Chapter 5 of the Arkansas Wheat Production Handbook at:

http://www.uaex.edu/publications/MP-404.aspx

Contact Information:

Please let me know if you have questions or comments at, jkelley@uaex.edu.  This and other crop information will be posted at http://arkansascrops.com/

 


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