Yeild Restriction

growing, harvesting, processing, cupping, purchasing

Yeild Restriction

Postby Jon Brudvig on Wed Feb 06, 2008 1:41 pm

Hello everyone. I look forward to participating in this forum.

I have had this idea for several months now, but haven't been able to connect with any farmer willing to give it a shot. If anyone could facilitate that connection, I would be very grateful.

A little background...

In a class given at the 2006 SCAA conference, Peter Baker described an experiment designed to test for any correlation between productivity and cup quality among two common varieties of Coffea Arabica. A research team gathered beans from both Caturra and Bourbon plants grown on the same farm, harvested on the same day, and processed and roasted in precisely the same manner. In numerous blind cupping trials, tasters rated the Bourbon significantly higher.

The experiment was conducted again. Only this time, researchers used flower removal to reduce the Caturra's yeild to an amount similar to that of the Bourbon's. In this cupping trial, there was no significant difference in quality. The coffees scored the same.

Caturra plants are a known to be a natural mutation of Bourbon, with the only difference being a single gene that promotes more branches and shorter overall height, leading to much greater productivity. More branches per foot of trunk equals more coffee per plant / acre / farm etc...

This study demonstrates a direct correlation between cup quality and yield. As yield goes down, overall quality goes up. In the wine grape industry, this has been realized for years. "Cluster thinning" is a very common practice, and growers often reduce their crop by as much as 50% by removing flowers and unripe grape clusters prior to ripening. The greater leaf to berry ratio forces more sugar and flavor compounds into the grapes, promoting overall quality and intensity of flavor. Yield restriction is even mandated by law in many wine growing regions.

My idea...

What if hand laborers removed a percentage of the flowers (or immature cherries) on an heirloom variety? Would the correlation between yield and cup still stand? If Bourbon cups better than Caturra, and the reason is the difference in yield... What would a yield restricted Bourbon taste like?

I have a strong instinct that if laborers removed 50% of the flowers on the distal part of each branch of an heirloom tree at bloom time, the cup quality would be significantly greater than that of a non yield restricted tree of the same variety. This statement also implies that the resulting coffee could out cup pretty much anything else we have seen if handled properly. Sure it would be an expensive coffee, but it could very well be worth the cost.

What does everyone think? I would love to get some feedback. I think there is some serious potential here that needs to be explored, and we would love to work on it with anyone who has the connections.

-Jon
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Re: Yeild Restriction

Postby barry on Wed Feb 06, 2008 1:44 pm

i've forwarded this to a friend who's a kona farmer.
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Re: Yeild Restriction

Postby Jeff Jassmond on Wed Feb 06, 2008 7:27 pm

Jon-

I mean this in the best way, but it seems like a no duh. If you're the first to think of this for coffee, that's really cool. I've always assumed folks had done experiments to determine the cup quality and financial viability of an approach like this, but being late to the game is what I get for assuming.

I don't have a ton of agricultural experience, but I can't think of a single plant I've worked with that does not produce better fruit when pruned to low yield.

Please keep me posted.

Jeff
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Re: Yeild Restriction

Postby barry on Wed Feb 06, 2008 7:50 pm

comments from a kona farmer:

It's probably true. Controlling yield is practiced in Kona Coffee through pruning methods. On one of our trees, we do not allow more than 3 verticals of the same bearing age. If you were to double the amount of verticals, the branches would bear smaller and lighter coffee. The yield would be some what larger though the quality & size of the beans would be less. Smaller beans. (Bob teaches the Beaumont Fukunaga method of pruning, annually to new farmers and that is the theory. Prune off older verticals, and select 3 new ones each year. Keeps a constant production.)

On organic coffee farms pruned exactly the same way, under-fertilizing causes less bearing and the coffee usually cups out a bit better although he is not convinced the flavor is worth the extra labor. He feels it would be foolish to ramp up the cost for what he says is a marginal difference.

We would never try to limit blossoms on our farm would be impossible- labor wise. We don't have that kind of labor available.
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Re: Yeild Restriction

Postby Jon Brudvig on Wed Feb 06, 2008 9:30 pm

Thanks a lot for the replies. It is great to hear the Kona farmer's take on the matter.

I would like to point out one distinction that needs to be made. Pruning restricts yeild by restricting the overall size of the tree. Fruit is reduced, along with leaf area.

A "blossom thinned" tree, on the other hand, would retain the same number of leaves as an unmodified tree. Only the number of cherries would be reduced. This means that each cherry is receiving sugars and other compounds from a greater number of leaves. Theoretically, the fruit (and it's seeds) would be sweeter and more flavorful, and would ripen earlier.

I think the fruit/leaf ratio is what is especially important here, and blossom thinning would have the greatest effect on this aspect. It would certainly be some expensive labor, definitely not practical in Hawaii.

I also think this needs to be explored both with wet and dry processed coffees. The wet processed example might be the fairest test, but I think the extra interaction with the fruit in a dry processed coffee might show a more dramatic change in cup quality.

-Jon
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