A Closer Look at Close Spacing
In the mid 80’s, researchers at the Texas A&M Research & Extension Center worked with Senninger Irrigation to develop the first Low Energy Precision Application (LEPA) sprinkler. Using LEPA bubble sprinklers close to the ground helped combat wind-drift and evaporation and helped them make the most out of the available water.
A few years ago, North Texas growers looked at combining conservation tillage practices with LEPA heads while closing up the spacing. This distributed water over most of the soil surface, increasing the application efficiency. The crop residue held the water in place, allowing it to soak in and fill the soil profile. As a result, fewer irrigation cycles were required to keep water in the root zone to promote crop development. For growers, this means irrigation can be reduced from watering over a seven day cycle to watering over a two day cycle.
Growers now use strip-till and no-till, switching their regular spray systems to LEPA bubble sprinklers, such as Senninger’s LDN Bubbler Pad and LDN Shroud, and strategically placing the sprinklers closer together and low to the ground. The exact spacing varies on Zimmatic machines from 27” to 30.96” (68.6 cm to 78.3 cm). The Senninger double gooseneck, combined with the Truss Rod Hose Sling, facilitates precise spacing by creating two drops from one outlet. Growers have seen significant water savings and increased yields, and Texas NRCS has endorsed conversion of existing center pivots and linears to a Precision Application – Residue Managed (PARM) sprinklers which qualify for funding.
Weather patterns have created renewed interest in this type of irrigation practice in many areas of the US. In addition to Texas, close spacing irrigation is now effectively used in Arizona, Nevada, New Mexico, California, Kansas, Colorado and Idaho. Growers are combining various components of this practice differently, which has resulted in great success. They have altered the spacing on the first few spans, combined spray application with bubble applications at various crop stages, varied the sprinkler height off the ground and even altered the application rate by irrigation cycle. Numbers vary by soil type and crop but typically there are yield increases and 20% water savings.
How do LEPA sprinklers irrigate?*
Bubble heads use less energy than conventional sprinklers and can operate at lower flows anywhere from 0.27 to 21.18 gpm (1 l/min to 80.2 l/min).
Senninger offers two types of bubble applicators:
The LDN Bubbler Pad deposits water straight down into furrows and distributes water in a narrow stream that avoids wetting the foliage. This aerated stream provides a cascade of bubbling water instead of a fine mist, so growers don’t have to worry about evaporation due to high temperatures and low humidity or strong winds blowing away fine droplets.
The LDN Shroud deflects water down in a wide dome-shaped pattern that gently distributes water without spraying. This type of bubble can be used on fields without furrows and on rolling terrains due to its less concentrated distribution pattern. The LDN Shroud is ideal for germination and low crop watering and for growers concerned about compaction of sensitive soils.
For more information about Close Spacing and LEPA sprinklers, visit www.senninger.com.
* “LEPA Irrigation for Drought Management. How to Make Pivot Irrigation 95-98% efficient.” By Senninger.