Ag Newsletter: July 2013

Soybeans at Crew Lake in Richland Parish

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

  • 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 seeds have separated from membrane, 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.

Soybean Reproductive Stages

  • R1
Beginning flower
Open flower at any node on the main stem.
  • R2
  • Full flower
    Open flower at one of the two uppermost nodes on the main stem.
  • R3 Beginning pod
    Pod is 5 mm (3/16 inch) long at one of the four uppermost nodes on the main stem.
  • R4 Full pod
    Pod is ¾” long at one of the four uppermost nodes on the main stem with a fully developed leaf.
  • R5 Beginning seed
    Seed is 1/8” long in a pod at one of the four uppermost nodes on the main stem.
  • R6 Full seed
    A pod containing a green seed that fills the pod cavity is located at one of the four uppermost main stem nodes.
  • R7 Beginning maturity
    One normal pod on the main stem has reached its mature pod color.
  • R8 Full maturity
    Ninety-five percent of the pods have reached their mature pod color.
  • 2013 Cotton Acreage by Parish 

    Below is cotton acreage mapped by the Boll Weevil Eradication Program.

    Parish: Mapped Acres

    • Avoyelles 6,275.68
    • Bossier 199.64
    • Caddo 11,417.21
    • Caldwell 1,576.65
    • Catahoula 15,439.47
    • Concordia 15,864.44
    • DeSoto 561.37
    • East Carroll 2,940.39
    • Evangeline 315.04
    • Franklin 6,727.11
    • Grant 1,618.21
    • Madison 11,248.35
    • Morehouse 1,067.89
    • Natchitoches 2,021.34
    • Ouachita 2,745.32
    • Pointe Coupee 1,588.63
    • Rapides 8,930.24
    • Red River 686.19
    • Richland 2,714.72
    • St. Landry 669.81
    • Tensas 32,950.26
    • West Carroll 17.23

    2013 State Total 127,575.19
    2012 State Total 225,760.26
    2011 State Total 284,964.00

    8/6/2013 12:41:31 AM
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