Irrigation Technology Helps Growers Cope with Drought

While the current drought has caused growers to pay closer attention to irrigation practices, results from the California Almond Sustainability Program (CASP) reveal how California Almond growers have increased water-use efficiency through equipment and technology, and are coping with tight water supplies.

Almond growers today use 33% less water to produce a pound of almonds compared to 20 years ago. Other improvements in production efficiency have resulted from:

More precise fertility practices; Higher-density planting patterns with alternating pollinizer rows and better bloom overlap; and Minimal pruning.

Advances in micro-irrigation and irrigation scheduling have also been major contributors to these improvements, and Almond Board–funded research has been key to that success.

Grower feedback from CASP suggests that about 70% of almond acreage is now under micro-irrigation (drip and micro-sprinklers) compared to the standard of flood and impact sprinklers 20 years ago. In addition, CASP shows that 83% of growers practice demand-based irrigation; that is, they use different technologies to schedule irrigations based on a combination of weather and evapotranspiration (ET), soil conditions and soil monitoring, and determining tree water status through leaf water potential using pressure chambers. In another area, the Almond Sustainability Report shows that 80% of growers take measures to design and install irrigation systems that are optimized for orchard conditions, and to maintain those systems.

In this time of drought, a key aspect of system maintenance is to ensure high system efficiency by determining distribution uniformity (DU). This subject is addressed in the May issue of California Almonds Outlook. See“Increasing Irrigation Efficiency — Testing for Distribution Uniformity."

The Almond Sustainability Report also shows there are opportunities for improvement by using additional tools for coping with drought. State-of-the-art irrigation scheduling should integrate the three legs of the stool — weather/ET, soil moisture monitoring and tree water status; however, the report shows only 43% of grower participants use weather/evapotranspiration (ET) as an irrigation scheduling tool, providing an opportunity to encourage adoption of this component to further improve efficiency.

During this period of drought, an important principle to follow under conditions of severe water restrictions is to spread out available water over the season in proportion to almond evapotranspiration (ET). Guidelines and instructions for using this technique are provided in the same May issue of California Almonds Outlook in the articles "Increasing Irrigation Efficiency — Scheduling Irrigations Using ET” and “Using CIMIS Data to Calculate ETc in the Orchard.”

Past Almond Board–funded research has proven that late-season irrigation is vital for next year’s crop. Water is needed during the period of fruiting-bud differentiation, which in normal years starts in July and continues to mid-September or even into October for later varieties and cooler years. Moderate stress during this period will have little effect on the subsequent year’s yield; however, severe stress can dramatically reduce bloom, fruit set and yield the subsequent season. For more information on this, see “Coping with Drought — Late Season Irrigation Is Vital for Next Year’s Crop” in the June issue of California Almonds Outlook.

Another article in this issue, “Managing Trees as a Collection of Spurs in a Drought Year,” discusses the relationship between spur development, fruiting, irrigation and drought.