With Irrigation, Timing is Everything

For farmers, deciding when to terminate end-season irrigation is all about timing. Producers must ensure soybeans receive their needed last irrigation without wasting water. 

The first step to determining when to cutoff irrigation is to identify what growth stage the crop is in. According to Mississippi State University Extension, having wet soil or applying a last irrigation just before R6 will ensure enough soil moisture is available to completely fill the soybean seeds.

If the crop has reached the R6.5 growth stage, when soybeans seeds have begun to recede from the pod membrane, and adequate soil moisture is present, irrigation can be terminated at this point. 

Soil moisture sensors can also be a useful tool to make decisions on cutting off irrigation. Combining sensors with an accurate growth stage identification can provide the information needed to estimate the time until the crop reaches maturity. 

Properly terminating irrigation on soybeans can help farmers avoid these two things:

• Terminating irrigation too soon can result in decreased seed size, which will ultimately result in soybeans not reaching their maximum yield potential. 
• Irrigation applied beyond the time of the soybean’s ability to use the applied water will result in over-irrigation, which wastes water and will result in a field that may not dry by harvest time.

As Mississippi farmers cope with a declining aquifer, it’s critical to adopt more efficient irrigation practices. For more information on increasing irrigation efficiency in the field, check out the MSPB Irrigation Guide.