Planning Final Irrigation
By Kyle Searle / August 2019
Kyle is a Barley Agronomist based in southern Idaho. He has been an Agronomist with Anheuser-Busch since June 2017.
Planning the final irrigation on a barley crop is all too often perceived to be much more complicated than it should be. By knowing the crop stage and estimating soil moisture content, making the decision on when to end irrigation is simple. By timing the last irrigation correctly, a grower can ensure a quality crop at harvest and make the most efficient use of water.
When crop kernels reach the soft dough stage, the barley plants require about 2.5 inches of available soil moisture. In a previous blog post “Barley Crop Stages, Growth, and Development” we discussed the different stages of a barley crop in Feekes. According to the Feekes scale, soft dough occurs around 11.2. For quick reference of soft dough, one can pull a random sample of kernels from the field, and when pinched, a fully formed kernel with a doughy texture will squeeze out of the hull.
Base the decision to water on the head not the stem. The kernels will turn golden and lose their green color before the stem. At this point, it will likely not increase yield or grain quality to irrigate after this point.
It’s important that barley has 2.5 inches of available soil moisture in order to finish out high quality, plump kernels, produce high test weight, and heightened yields. However, more than 2.5 inches of moisture after the soft dough stage will result in inefficient water use, increase lodging, and reduce quality.
In heavier soils with water holding capacities at or above 2.5 inches, irrigation can be ended at the soft dough stage (Feekes 11.2), if holding capacity is full. In sandy or shallow soils with lower water holding capacities, more irrigation should be applied after soft dough is reached but should not exceed 2.5 inches or be applied after green is gone from the kernel.
Timing It Right
To time your final irrigation right, it is best to answer these questions:
- Has the barley reached or close to soft dough?
- What kind of soil do I have, and what is the relative water holding capacity of my soil?
- How much soil moisture is currently available to the plants, and how much more, if any, will be required to reach 2.5 inches?
By checking the fields and answering these 3 questions, planning and timing the final irrigation should be fairly simple. By timing that final irrigation correctly, you will likely see better quality at delivery and more efficiently use water resources.
Robertson, L. D., and Jeffrey C. Stark. Idaho Spring Barley Production Guide. University of Idaho, 1993.