Producers soon will be planting their 2017 wheat crop. Variety selection is one of the most challenging decisions that needs to be made, but you also need to remember that the wheat seeding rate is a very important component to establishing your wheat crop.
Recommendations in Kansas are often stated in terms of pounds or seeds per acre, and vary according to different precipitation zones. However, seed size can have an impact in the final number of seeds actually planted per acre. A variety with larger kernels or less seeds/lb., when planted according to pounds per acre recommendations, will result in fewer seeds planted per acre and thinner stands than a variety with smaller kernels.
So if the weather and fertility during the growing season are not favorable for tiller formation and survival, grain yields may be reduced due to the thinner stand.
On the other extreme, a variety with small kernels planted according to pounds per acre recommendations can result in above-optimal stand establishment, increasing competition for available resources such as water and nutrients.
So an advantage of planting wheat in terms of seeds per acre rather than pounds per acre is that seed costs can be reduced for varieties with a small kernel size. Seed size can simply be measured in terms of the number of seeds per pound.
The “normal” range is about 14,000-16,000 seeds per pound for most wheat varieties, but it can range from 10,000 seeds per pound to more than 18,000 seeds per pound. Although seed size is specific to each individual wheat variety, it can also vary within a variety depending on the seed lot and the seed cleaning process.
K-State Research and Extension studies have shown that wheat variety plays a major role in determining wheat kernel size, as does the quality of seed cleaning. So seed cleaning is very important if you are keeping and planting your own seed. This will ensure the final amount of seeds planted per acre will be close to your original target.
Certified seed, or seed submitted for germination testing, will provide for you the seeds/pound. The 2017 Wheat book also provides a reference to the seed size tendency of varieties. However, an easy on-farm method to estimate the average seed weight is to collect several representative 100-seed samples and the weight of each of those samples in grams. Then to calculate the seeds/lb., simply divide by a conversion factor and the average weight of the 100-seed samples.
There is also a quick reference guide available to help you adjust the planting rate in pounds per acre based on the wheat variety seed size and the targeted number of seeds planted per acre. This is below or available at any of the Post Rock Extension District Offices in Beloit, Lincoln, Mankato, Osborne or Smith Center.
The recommended wheat seeding rate for a dryland wheat producer in Central Kansas is about 750,000 to 900,000 seeds per acre, which calculates to about 50-60 lbs. with a final stand from 600,000 to 720,000 plants per acre. Then you simply use your seed size to increase or decrease the seeding rate along with your cropping system used and your planting date.
Contact me if you have further questions on wheat seeding rates at any Post Rock Extension District Office.