R. Keith Collins | 8/1/2012 11:52:46 PM
Soybean Irrigation Termination
Each year soybean producers must decide the optimum time to stop irrigating soybeans. Research has shown that failing to provide adequate moisture through maximum dry weight accumulation can result in as much as 10 bu/acre yield loss. A good rule of thumb for terminating irrigation is to determine if 50% or more of the upper two pods on plants have seeds that are touching within the pod. This will usually correspond with R6 – R6.5 growth stages on Group IV varieties. At this point, if there is good soil moisture then irrigation can be ended. If soil moisture is dry or becoming dry with little or no chance of rain then soybeans will benefit from a final irrigation.
Soybean Harvest Aid Timing
The dominant soybean varieties planted in this area are indeterminate Group IVs. Indeterminate varieties begin flowering in the lower portion of the plant but continue to grow for several weeks after flowering begins and tends to retain leaves longer than Group V varieties. Seeds at the bottom of the plant mature first with most of the immature seeds in the top of the plant. For these reasons, harvest aids are of value to allow for earlier harvest which may allow growers to take advantage of higher prices for earlier delivery. Expediting soybean harvest is also beneficial because mature soybeans do not withstand adverse weather conditions very well and can lead to reduced yield and seed quality.
Timing of a harvest aid such as Gramoxone is a decision producers must make each year that allows for earlier harvest as well as maximizing yields yet applying too early will reduce yields. Below are conclusions and recommendations for Group IV soybean harvest aid timing from results of research conducted by Dr. Jim Griffin, weed scientist with the LSU AgCenter.
Determining when to apply harvest aids:
· Collect pods from the uppermost four nodes of plants at random across the field.
· Open pods and look for separation of beans from white membrane inside the pod.
· If separation is observed on all pods collected, then seeds are at physiological maturity (50% moisture) and have reached maximum dry weight.
· At this stage some leaves have dropped and remaining leaves are yellow.
· Harvest aid can be safely applied without affecting yield.
If after opening pods not all seed have separated, then an application of harvest aids will result in some yield loss. These recommendations are based on earliest application timing without sacrificing yield. Producers will need to decide if yield loss from earlier applications can be offset by other benefits associated with early harvest.
2012 Cotton Acreage by Parish
Below is cotton acreage mapped by the Boll Weevil Eradication Program. Thanks to Gene Edmonston, LDAF, for providing this data.
|2012 State total||225,760.26|
|2012 State total||284,964.00|