This year has changed the game when it comes to double cropping soybeans. Typically as July small grain harvest progresses producers no-till soybeans into stubble. However with the late timing this year Extension Agronomist Del Voight reports many are asking when is it too late to plant?
The continued rains and ideal planting conditions are an advantage that may compensate for the late planting. Voight has seen fields planted directly after barley that did emerge almost immediately with the rains. We have ample moisture in the soil right now and it appears that moist conditions may continue. It takes about 90 days for soybeans to develop pods and dry seed so if we get an average frost we need to be planting beans by July 15- August 1 in Pa to be in the window for harvest based on average frost free dates. If you are in a part of PA where the typical first frost is around November 1, you still could still plant soybeans.
Voight shares these other factors to consider if you are evaluationg planting beans. First you should plan to establish at least a a minimum planted population of 200,000 which is recommended for double crop beans prior to July 5. However since that date is past, 220,000 plants per acre pa might be in order to ensure ideal canopy cover.
Plant in narrow rows of 15 or 7 inches with the narrower width preferred. There is less time for the soybeans to gain height to pod so the narrow rows allows for more beans to grow at higher populations.
If the field has visible weeds be sure to burn then down to ensure weed competition is kept to a minimum. Next set a realistic economic target. Traditional double crop yields of 30 bu/acre are not out of the question. At $9/bushel for soybeans there is some but not a lot of room to spend input costs over and above that which needs to be spent to make the crop. This simple table best illustrates the impact of planting date.
Be aware that an early frost is possible and if forage is needed consider management for a forage use of the soybeans. If the goal is forage supply, then perhaps sorghum sudan or another annual crop may be a better selection.
There has been talk about moving to a shorter maturity for this late season. Past experience in this area would suggest full season maturities for double crops may out yield short season maturities. Our double crop beans planted with full maturity over the last several years have matured with no ill problems in the fall. Last season which was also a wet season our Lancaster Double Crop Soybean Trials averaged 54bu/acre planted on June 24th at 220,000ppa. To view the maturity and varieties please visit: http://extension.psu.edu/plants/crops/grains/soybeans/soybean-variety-tests/2014-reports Pennsylvania Soybean Performance Test 2014.
Dr Dave Holshour from Virginia Tech has studied the impact of delayed planting on maturity. He reports for April and May plantings a 3 day delay in planting resulted in a 1 day delay in maturity. For example if the crop is planted 30 days late this would cause a 10 day later maturity. However in the June and July plantings a 5 day delay in planting will result in 1 day difference in maturity. For example if planting 15 days later the crop would only mature 3 days later than normal. It is most important to plant a maturity group that would grow as long as possible in the vegetative stage to gain height before flowering which allows for an adequate canopy for maximum yield and still enables maturity before a frost.