The recent hot and dry weather is really drying the wheat down quickly. We harvested our first wheat today (the moisture was ranging from 16 to 20%) and planted soybean immediately afterwards. Just 2 days ago, the wheat grain moisture was in the mid-20’s!
That experiment is part of our ongoing efforts to harvest higher quality wheat and increase our double-crop soybean yields. Now, I’m not advising you to harvest your wheat at 20% unless you have a buyer that will take it, preferably without a discount, or you have a way to dry down quickly. High moisture wheat will heat up quickly and you will need to do something with it right away.
With that said, we have seen great benefits from harvesting higher moisture wheat and getting the soybean planted immediately. Our Mid-Atlantic regional project conducted from 2015 thru 2017 found greater wheat yields and test weight, and greater soybean yields. Our data is shown below. Note that I’m only showing Virginia wheat data as the date where yield began declining differed among the states (this data was earlier as we moved south), but the general shape of the graph was similar. Different colored symbols represent different years.
Note that our soybean yield usually start declining rapidly in mid-June.
In summary, there is benefit from harvesting wheat and planting soybean as soon as possible. However, read the previous blog, To Plant or Not to Plant into Dry Soil, before making too many decisions. Not only is our topsoil dry, but the wheat may have removed moisture much deeper – giving us little total soil moisture.
It’s hard to believe, but June is here and we need to start thinking about increasing our soybean seeding rates. I’ve been recommending only 100 to 115 thousand seeds per acre for full-season production, enough to give you 70 to 80 thousand plants – yes, that’s all you need to maximize yield.
But as the season gets shorter, yields will start falling with delays in planting date. On average, we lose about 1/2 bushel/acre per every day we delay planting after the middle of June. The graph below shows the results of last year’s 4-state early wheat harvest/soybean planting double-crop study. Note that yield does not decline very much during the first week or two of June, but rapidly drops off afterwards.
The main reason for this yield decline is that the crop struggles to develop enough leaf area to capture 90-95% of the sunlight by early pod development, due to the shorter growing season. We can alleviate some of this by narrowing rows and increasing seeding rate.
I usually suggest that farmers plant enough seed to result in a final plant population of 180,000 plants/acre for double-crop soybean. That means planting 200,000 to 220,000 seed/acre. Yes that is a lot of seed, but my research shows that yields (and profit) continue to increase up to this seeding rate, especially when planting is delayed until late-June and early-July.
There are stipulations. More productive soils and irrigated soybean usually require less seed. Good years that allow lots of quick growth require less seed (but who can predict a good year?). Later maturity groups may require slightly less seed. Less seed are needed as you move south (growing season is longer and you can plant a later relative maturity). I think that a soil profile that is full of water at soybean planting (this year) might allow less seed to be planted – but I have not documented that – It just makes sense to me that plants will grow better when the small grain has not depleted most of the subsoil moisture.
What about now? How many seed/acre do we need to plant in the first week of June? Here are my suggestions. Keep in mind that these are general guidelines; you need a gradual increase in seed/acre. I’m assuming 80 to 85% emergence for June/July plantings. To easily determine how many seed you need per row foot, see VCE pub 3006-1447, Suggested Soybean Seeding Rates for Virginia
May: 100 to 115K
June 1-7: 120-140K
June 8-14: 140-180K
June 15-21: 180-200K
June 22-30: 200-220K
VIRGINIA SOYBEAN FIELD DAY
Thursday August 20, 2015
Eastern Virginia Agricultural Research & Extension Center
2229 Menokin Road
Warsaw, VA 22572
Virginia Soybean Association
Virginia Agricultural Experiment Station
Virginia Cooperative Extension
Join us to see the latest research on soybean varieties, disease and weed management, IPM and sorghum varieties. Experts will also demonstrate no-till drill maintenance and update you on the mid-Atlantic double crop initiative. Registration begins at 8:00 am and field tours begin at 8:50 am. The program will end at noon with a delicious meal by Nixon Catering.
– Soybean Disease Management – Dr. Hillary Mehl
– Soybean Weed Management – Dr. Mike Flessner
– Soybean Insect IPM – Mr. Mike Parish and Drs. Sean Malone and Ames Herbert
– No-Till Drill Maintenance – Mr. Keith Burgess
– Grain Sorghum Management – Dr. Joseph Oakes
– Roundup-Ready Public Soybean Varieties – Dr. Bo Zhang
– Mid-Atlantic Double-Crop Soybean Initiative – Dr. David Holshouser
We hope to see you there!