Once again growers are dealing with limited water availability, further emphasizing the importance of efficient irrigation approaches. UC Cooperative Extension Nut Crop Farm Advisor, Mae Culumber said that last year’s water stress and early season heat led to many reports of smaller nuts. To help mitigate negative impacts of limited water supplies, adapting appropriate water budgeting practices will be essential.
“When we talk about water budgeting the first and foremost thing is to get a sense of what the evapotranspiration of the tree canopy is,” said Culumber. “You can look at the historical average for that period of time to give you an idea of what the water loss is and what the applied water needs to be. Or if you have access to real-time ET monitoring, that’s also very useful.”
Culumber, who was recently selected to be the Presidential Chair for Tree Nut Soil Science and Plant Water Relations at UC Agriculture and Natural Resources, explained that a thorough understanding of soil moisture will play a crucial role in proper irrigation programs. Regulated deficit irrigation is another approach that can provide some benefits for growers.
“During hull split, it may help to do. Depending on your soil type and the moisture-holding capacity, you could do maybe between a 15 to 25 percent deficit in irrigation in that time,” said Culumber. “So, that could be a nice savings in terms of water, and it could also help offset problems that you might see from developing hull rot infections.”
Monitoring the performance of irrigation systems and conducting routine maintenance will also be critical to ensure efficiency. Irrigation approaches will also need to take water sources into consideration. Increased temperatures and reduced water flows can create higher concentrations of salt.
“When you have low flows, we tend to see a decline in water quality,” Culumber explained. “When you’re dealing with a different quality of water that you’re pumping into your irrigation system, this could affect your application rate and the functioning of your irrigation system and how well the distribution uniformity is applied across a field.”
Listen to Culumber’s interview below.