First, the usual disclaimers: I am not an expert. I have time to cruise around the internet. By the grace of God I have friends who ARE experts and they are willing to share their expertise. Yes, Billybob, I am talking about you.
Pecans
Pecans have an interesting native range.
Many botanists believe that pecans were spread from their original, very limited range in east Texas and Oklahoma by humans. Pecan (nuts) make almost the perfect travel food. They float if they fall in a river. They can be picked out of the dirt if spilled. They can be carried in a quiver or bag without contaminating other luggage.
The current thinking is not that Native-Americans deliberately planted pecan groves but that lost nuts (maybe the person carrying them died) sprouted and grew. They had nuts and progeny.
That story would account for groves of pecans stretching out along rivers far above the majority of the pecan's range. It would also account for the disjunct communities in Mexico, near Alpine, Tx and in northern Missouri.
The coming of Europeans was tough on the pecan. Trees were cut down to harvest the nuts. Bottomlands were burned to plant corn. Cattle, goats and sheep were grazed.
Let's zoom into northern Texas and western Oklahoma
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| Average annual rainfall |
We can form a rough approximation for how dry (rain-evaporation) pecans can survive by looking at the western-most pecan range along the Red River that separates Oklahoma from Texas.
South of the river, the pecan range is at about 30 inches of rain a year (average) and 64" of evaporation for a net dryness of 34 inches of water. That is, a net LOSS of 34".
If you look at the north side of the river, the dryland pecan range extends almost to the Texas panhandle. If we assume the rainfall and evap are well behaved then we are looking at 24 inches of rain and 73 inches of evap for a net dryness of 49" of water.
It is important to use "dryland" range because pecans growing in river bottoms can access the water table adjacent to the river and net rainfall is not pertinent.
Survival does not mean economically viable
Pecans and most other nut trees have the ability to set a larger crop load than they fully ripen or fill. During good years they "fill" the nuts. In dry years the shells contain shriveled boogers.
US consumers are used to buying uniform, plump, brightly colored nut meats. That is made possible by a high-tech infrastructure which relies on a steady supply of high-quality, low cost fuel and petrochemicals. Some of that fuel is used to deliver irrigation water for those orchards that are in the drier pecan growing areas.
Dryland pecans are like blue-jeans you buy at the thrift store. The pecans US consumers are conditioned to buy are like name-brand sports wear.
Establishment
It is my belief that many species can grow in drier areas than where they are "native" because seedlings have shallow root systems that do not compete well against sod, mesquite, juniper, sagebrush, Russian Olive, tamarisk and so on.
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| Notice that the trees are widely spaced and that most of them appeared to establish in lower areas where run-off would accumulate and wind-velocities might be lower. |
As adults, those species can strike their roots deeply enough to mine water from enough soil/rock to survive as long as other deep-rooted competitors (see list above) are kept at bay.
The canal that accidentally grew a forest. A video on Youtube about a construction project in Arizona that interrupted the natural flow of water as it sheeted across the landscape. The water ponded and sank into the ground. That provided enough of a difference to start a wooded belt.
And thus, my question is answered. Thanks ERJ! Super interesting history and yes, there is a great divide between "commercially viable" and "growing a tree or trees" for pecans.
ReplyDeleteAhh... that great divide is where cultivars like Major and Kanza (a Major daughter) shine. Unlike many pecan varieties, these two (and probably other Major offspring like Hark, Yates 68, and other local selections) have the capability, when presented with insufficient moisture to fully fill kernels in a full-sized nut, they reduce nut size and just fill a smaller kernel. Hence, if I were growing on an upland site (some of my place is like that) without ability to provide some supplemental water... they'd be the first varieties I'd try, if they were suitable for my zone/climate.
ReplyDeleteRead more on 'Major' and its genetic contributions, in this thread from Dr. Bill Reid's Northern Pecan blogspot:
ReplyDeletehttp://northernpecans.blogspot.com/search?q=major+
There was a huge pecan farm out west of San Antonio. They'd been flooding the orchard for almost a 100 years, irrigated from the Edwards Aquifer... Then San Antonio decided they owned the water and cut them off.
ReplyDeleteSeguin, Texas has a natural watering from the Guadalupe river and the rainfall out there in that part of central Texas supports pecans, and other farming without much need for irrigation. At least from the looks of the green as I drive through there.
Arizona was a major Pecan producer, but one of the last remaining major producers just announced their shutdown, interestingly at the far end of the same CAP canal system supplied area described in the video, south of Tucson. Growing up, all the canals were lined with Pecans and if you new the farmers they would let you gather in the late fall. Now they are considered too water intensive and almost all of those are gone.
ReplyDeleteBTW, the video and most of the permaculture 'experts' always seem to neglect to describe the full effects of their swales and forests on the uphill side. These improvements restrict important moisture to the downhill side.
Gov. Ducey finally reintroduced an idea from the mid-1900's - we (Arizona and SW US) need to desalinate. It is not that far to the Gulf of California, and although high salinity, that water will not run out even if the Colorado runs low for a few years.
In regards to the water/irrigation issue, would not the drip irrigation methods utilized quite a bit in Israel be a possible solution, and a much more effective means of water usage in the dryer western states? Granted, there would probably be a high initial investment cost, but I think the returns, and the more judicious use of water resources would make it pay.
ReplyDeleteThe advancement of mesquite into north Texas, Oklahoma, and Kansas has depleted the water table to the point that pecan orchards/trees are few and far between, compared to the 1800s/early 1900s.
ReplyDeleteDid you know that the pecan is a variety of the hickory? You'll find pecan groves well into south and western Texas, if there is water proximal, i.e. live streams and rivers. They compete with the cypress trees. We have lots of them here in the Brazos valley. I find your theory eminently believable for East Texas and Oklahoma, because these tribes were agriculturally-inclined, if I recall, unlike the hunter tribes like the Comanche and Comancheros, further west.
ReplyDeleteA good friend's grandfather was the ag teacher at the local (rural Central Texas) high school from the early 50s to mid 80s. He was also a quite prolific grafter of pecan trees. He kept a notebook detailing every graft he made. We never counted them but I bet there had to be at least 700 entries. We've located quite a few and they are still going strong.
ReplyDelete