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2021 AlmondBeat 6: Deficit irrigation - revolutionized. optimized‏

Updated: Jul 26, 2021

One of the effects of the severe weather conditions this season in Central Valley, California, is that almond growers have entered harvest sooner than usual. In fact, for the first time in many years they're shaking trees together with their Israeli peers. Nationality, of course, doesn't play a role in optimizing this critical stage of the season. What's important is to be able to listen to the universal language of trees, and deliver irrigation according to what they are "telling" us.

What is at stake here is both the present - and the future - productivity of the farm.

2021 AlmondBeat here we go

A delicate balance

One of the pitfalls during harvest is barking (when the bark tears away from the tree). The main reason for it is that trees are too "wet" carrying excess moisture in their trunks which makes them susceptible to damage during shaking. A common practice is to "dry out" the trees before shaking them.

But exactly how much time and how much stress should growers apply without affecting the tree's future health and productivity? When is the optimal time to cut irrigation and push the trees into negative growth and how much time should they stay thirsty?

A preharvest formula

By cross-checking direct data from the blocks (trees' trunk size and water demand, actual water delivery, and block's stress history) with information supplied by our customers (actual barking rates in their fields) we have identified a practice that helps our customers use deficit irrigation tactics to avoid barking while keeping trees healthy and avoiding too much yield-affecting stress.

We found out that avoiding positive growth 3 days before shaking significantly reduces shaker damage and helps in optimizing this stage. Cutting irrigation, inducing stress (red plant status), and stopping trees' growth 3 days before shaking can lead to "zero barking" and better rate of nut removal.  

"Trees just look great"

Osher Carsanty, Farm manager at Degania Bet Kibbutz, sees a significant improvement after switching to Phytech's formula for deficit irrigation.

"Following Phytech's recommendations, we have managed to cut in half the days in which we don't irrigate at all", he told our Customer Success manager, Yuval Keinan, "Trees just look great. Not a single one was harmed during shaking".

Almonds harvest at Degania Bet Kibbutz

Farm Manager, Osher Carsanty

Backed by science

This practice is also supported by a research conducted by a UC Davis team led by Prof. Ken Shackel who has used our dendrometers to measure day-to-day trunk growth. 

"A reduction in trunk growth before shaking may decrease the susceptibility of the trees to shaker injury", wrote the researchers, "Nine trees were given excess irrigation before harvest. They maintained trunk growth, and 8/9 were damaged by the shaker. Only 3 trees in the standard (control) treatment were damaged". (Lysimeter –Whole Tree ET Response to Mild and Moderate Water Stress, Shackel et. al 2019)

Back on the growth track

After shaking, it is super important to get the trees back on the positive growth track to maintain their health and future productivity. Again, Phytech users get instant and clear visibility of their trees' response to irrigation and growth rate.

By directly tracking the trunk diameter changes in real-time, Phytech (compared to indirect sensing methods such as soil, drone and satellite) is the only technology that enables growth monitoring on a daily resolution.

That's it.

See you on our next AlmondBeat report which will cover post-irrigation best practices.

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