AgEBB - Agricultural Electronic Bulletin Board

When Should the Last Irrigation of Soybeans Occur?

Joe Henggeler, State Irrigation Specialist

Step 1. Pull up typical plant.

Step 2. Tear off all leaves.

Step 3. Count down from top 4 nodes; tear plant here and discard bottom part.

Step 4. Find the pod that is most fully developed; key off of that pod.

Step 5. Use stage of that pod and Table 1 to decide on whether to continue irrigating. See accompanying photograph of soybean stages of growth.

Table 1. What Maturity Stage to be at for the Last Full Irrigation
	Without Hardpan		With Hardpan Above 10 inches
Soil Type	Sprinkler	Flood	Sprinkler	Flood
Coarse sand	R6 ⁺⁺⁺	R6 ⁺	R7	R6 ⁺⁺
Fine sand, Loamy sand, Clay, Clay loam	R6 ⁺	R5 ⁺⁺	R6 ⁺⁺	R6 ⁺
Sandy loam, Fine sandy loam, Very fine sandy loam	R6 ⁺	R5 ⁺⁺	R6 ⁺⁺	R6 ⁺
Silty clay, Silty clay loam, silt loam	R5 ⁺⁺	R5 ⁺	R6 ⁺⁺	R6

Table 2. Later Soybean Stages
Stage	On the top 4 nodes:
R5	One pod has beans that can be felt.
R5⁺	1/3 of pods have beans that can be felt.
R5⁺⁺	2/3 of pods have beans that can be felt.
R6	One pod has touching beans.
R6⁺	1/3 of pods have touching beans.
R6⁺⁺	2/3 of pods have touching beans.
R6⁺⁺⁺	Nearly all pods have touching beans.
R7	One pod has final mature color.

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Questions or comments about this website? Please contact Joe Henggeler via e-mail: HenggelerJ@missouri.edu or phone (573-379-5431); University of Missouri Delta Center/Portageville, MO 63873