Mesquite "nurse" tree hugel experiment...

Good Evening Fellow Permies,

I have an abundance of surplus logs on my property so I thought I would try an experiment. I will build a massive crescent shaped hugel around the base of a fairly mature mesquite tree (photo of the first morning's work attached).  Once the hugel is built, I will plant ground cover, herbs, shrubs, etc.... on the mound, then try to plant a tree in the middle. Preferably a tree that is borderline for my zone 8B with only 14 inches of rain per year. The reasons for this experiment are as follows... 1) Is it true that mesquites are a decent "nurse plant" that provide nutrients and shade for other plants to thrive under their wonderful dappled shade canopy, or will the mesquite roots outcompete other plants for water? As the wood in the hugel decomposes, how will the central tree perform? 3) Will the central tree thrive on neglect being surrounded by such a bounty of carbon, etc...?

This spot is not ideal as the mesquite is on the northeast side of where I am going to plant the tree, however I do have mountains, cottonwoods and a sycamore nor far away to the northwest which helps alleviate the harsh afternoon sunshine that we see in Arizona.

I don't know what to plant yet, but I am leaning towards a nut tree, possibly a walnut. I want something that could potentially get very big as shade is a major asset here.

The big question is, how would I define success? I would imagine that success would be the mesquite slowly dies back due to excess moisture, shade, chop and dropping, etc... and the new plants thrive and take over the area. BTW, I have nothing against mesquitee trees, but I have dozens of them on my property so I am trying to add diversity and explore the potential of hugelkultur in my area.

I hope to keep you all posted on my progress. Let me know if you have any tips for plants I might want to consider planting in this endeavor or if this entire project is a fools errand for one reason or another.

hi Stan, sounds like a plan...

I spent a bit of time wandering AZ on my bike a while back... so I did some observations and such there.

I'll start by saying that hugul mounds might be a fool's errand, as you say, in your arid location, but burying the wood below-grade might be a much better option.Buried Wood Beds permie thread  you might want to research a different tree to plant unless you have a lot of water.  Here is something I found about walnuts:

As a first rule of thumb, the average commercially grown walnut tree needs 1270 mm (50 inches) of precipitation every year. As a second rule of thumb, the walnut trees need more than 50% of the annual water supply during summer (June, July, and August).

 Check out This link that includes things that do grow under mesquite In this case, if you have some water to nurse the plants through a couple of seasons, I would go with trying a Texas Mulberry tree, some Wolfberries, and a desert hackberry tree which can grow large with some watering, with an understory of a local wild grass and maybe some softer plants like chia, and amaranth type species, like lambs quarters.

When building your hugul or buried wood bed make sure that you do not have the wood touching each other.  Bury each piece and pack the soil between the pieces and layers, moistening the layers as you go, add as much nitrogen-rich materials as you can to aid in the woody breakdown.  

Mesquites are a nitrogen fixer.  They provide nitrogen to other species in ecosystems but put out a lot of nitrogen into their leaves, pods, and seeds.  Pods especially.  You probably know that the whole pod and seed combination is a very nutrient-dense food source when milled to a powder.  As far as them competing for water, it depends on your location's water table, probably, but judging by the fact that you have nearby cottonwoods, I'd say that this isn't an issue.  If you don't know your water table depth and how that might affect this, go for a hike in the wildlands nearby and look to see if anything is growing under its canopy. I would think that mesquites are also very good candidates for FMNR  Hack them to the ground at some point, and they will regenerate from their deep roots, and then choose the strong shoot to provide a canopy for other trees, while having continuous sprouting of young softer material for use as mulch or compost or rocket fuel.  

The big question is, how would I define success? I would imagine that success would be the mesquite slowly dies back due to excess moisture, shade, chop, and dropping, etc... and the new plants thrive and take over the area.

I like how your imagination works. :)

my two cents as an arizona native....

IMO, anything you do to improve the mesquite's situation ...  the mesquite will take advantage and out compete anything (in way of another sizeable tree) underneath or nearby its canopy.