Water Production Function Paper - Spain

Attached is a research paper from a group out of Cordoba, Spain. They conducted a research trial looking at the effects of variable water applications on almonds. Although the findings aren't "new," they concluded the following:

• Yield increases with increasing water applications;
• Nut size and nut counts were affected within the long term trial;
• Reduced nut counts seems to be due to the smaller tree size due to the prolonged stress;
• There were no differences in overall yield, kernel size, or nut counts when comparing the same levels of irrigation utilizing proportional seasonal deficit irrigation and regulated deficit irrigation during hullsplit.

I thought the last point was very interesting as it counters the belief of RDI research in CA. In some ways, however, it matches my experience. I always thought RDI was just a way to deplete stored soil moisture going into harvest. In practice, I find it  too difficult to manage. 

Furthermore, my when conducting trials on RDI, I never observed the "promoted benefits." On one farm, i helped establish a replicated  RDI trial, they ran it as perfectly as possible on a farm - trees never experienced more than -18 SWP on the pressure chamber. Yields were reduced by 5-8%, variety dependent, while water savings were around 7%. Stick tights were not reduced and we did not increase harvesting efficiency. After the losses, the grower refused to run the trial again.

Let me know if you would like to discuss further,

David