In a couple of weeks I will be planting 150 bare roottrees on a piece of property that used to be a golf course. It’s so well drained that the surface is dry within minutes of rain ending. I’ve toyed with a few ideas to help each tree get more water and hold it longer.
One is to dig deeper than usual and put in a layer of wood chips at the bottom to sort of create a hugelculture, buried-wood effect.
Another is to poke several holes through the turf around newly-planted trees to encourage more water to drain in the vicinity of the tree’s roots.
20 acres, previously farmed with tree lines, 36' of elevation change over 1,300 feet of south facing slope, 7,000+ trees planted so far in previously tilled acres at a density of ~500 per acre.
My soil pretty much defines "Well Drained" not counting the rocks (and there are a LOT of rocks) it's 99% sand and perhaps 1% clay, silk, and organic matter.
I took the "Mulch Pit' idea from the grey water folks for my fruit trees and so far it's been working great. I dig a hole about 6' in diameter and 20-24" deep. I mix some compost in with the bottom layer of 'dirt' so I have 4-6" of mix, and build a 2' diameter wire cage from 1/2 hardware cloth (to keep out the gophers). I put the tree in the center of the cage, which is in the center of the hole, and then fill the cage up with a 50/50 mix of soil and compost. I fill the rest of the hole with mulch (shredded trees, bushes, etc. from the composting facility).
The mulch helps keep the bottom of the hole moist even when it's hot and dry out. After the first year the mulch has composted down a couple inches and I fill it up again.
I have got some really nice peaches and nectarines off those trees so this year I'm adding apples, pears and pluots with the same type treatment.
Southern Arizona might be the wettest desert on earth, but it's still a desert. Growing food here is turning out to be a bit more of a challenge than I expected.
My opinions are barely worth the paper they are written on here, but hopefully they can spark some new ideas, or at least a different train of thought
Terry, Im not sure woodchips will have the same effect as logs, because they are small peices. So they wont have the ability to slowly release water like a log. But woodchips in the ground will definitely rob nitrogen from the soil, due to there small size and quick breakdown within a few years. It can be very bad when you mix woodchips into the soil, because it can rob nitrogen to such an extreme degre. If those woodchips were properly composted, or turned into biochar then definitely use them; of course you need to charge that biochar with something for best results. If you don't have access to any composted organics, like hores manure or the ability to make biochar. A tree burm may be one of your only option to increas water capture of your new planting. If you can access old hay or straw, lay them down in about 2" thick layer to cover the soil, which will protect from evaporation. If you have wood chips layer them over the top of the hay for extra protection. You can do a 3-5" layer over the hay. Cover the inside of the burm, the burm itself and outside the burm as well. It will work for weed suppression too. Just thin out those layers to avoid covering of the graft union. You would be surprised the increased moisture retention from that layering. If you want to really get permaculture with this planting, and you also have access to used cardboard. Use some pieces of cardboard inside the tree burm like a weed barrier, put some wine cap mushroom spawn on the previously soaked cardboard, then put down the hay layer, and woodchip layer over the hay. That mycelium will work for majority only hardwood chips, if your woodchips are majority conifers, blewit mushrooms are the needed gourmet variety to compost conifer chips. Those are 2 very dominate mushroom species that don't require a sterolized substrate to grow in. Even if the mycelium doesn't produce a viable crop, it will quickly turn those materials into a thick rich organic layer, the worms will encorperate into your soil. If you do this project right, you may have lots of mushrooms to sell this fall, and every spring/fall even after you start fruit cropping, simply by using free available resources to increase fertility on your orchard. Just remember to keep your graft union above ground and or the mulch layer , so your scion doesn't root, and supersede your rootstock.
One other thing that will definitely help, but more in the long run, as in between a season to a full year. Is planting mixed annual cover crops in that orchard. If its an option, seed in some mixed species annuals. Do like a 9 or 12 seed mix of legumes and companion annuals grasses that do well together. You can do warm and cool season plantings. I would recomend at least both for the first year if your soil is that bad. Once your annuals get to maturity, you can graze 1/3 to half that biomass, if you have use for the forage, before rolling it to terminate the crop; then after termination, you can do your next planting of mixed species annuals. The mix can be made for warm and cool season covers, and in one year will create at least 12 tons of organic dry matter per acre, with about half below the soil, and the rest on the surface. Its the fastes cheepest, and least labor intensive way to solve your problem as a whole. Plus if you do those top dressings of hay and woodchips I mentioned for tree planting. The top dressing will keep those annuals away from your new trees. That mixed annual method also breeds fertility, so as your trees develop, they develop there roots out into a rich fertile soil.
Because the land was a golf course, they most likely took away all the organics by bagging, and the monocrop grasses used were perennial grasses, which most likely didn't contribute much organic mater via there root systems to the soil. They may have also intentionally added fines that are well draining, spacifically to dry out quickly.
The mixed season annuals is the cutting edge of tried and true method at achiving the goals you're after. That will allow your soil to hold more water from the composted biomass added underground, and the rolled plants on top protect the soil from getting to hot, which slows evaporation. Also the rolled plants themselves help slow soil evaporation, by slowing air circulation on the soil surface. The organic matter from the mixed season annuals creates a soil food web food, and the worms will move that matter around at a rate of tilling about 3 times per year, only they will be helping the soil web.
You need the right mix of legumes and grasses for your zone and season to work best. If you need help coming up with a good cool and warm season mix, let me know.
Living Web Farms YouTube channel, has a great webinar on mix season annual cover crops, that really explains these concepts and results very well.
If its feasible, consider those options, and you could be growing forage in between your fruit trees, that sheep could graze without harming your trees. You could still do mushroom farming in the mulch that keeps weeds away from your trees, and you'll have 3 crops in one feild, that work in symbiosis to create low maintenance, low overhead fertility in your orchard.
Also consider spawning your trees with a gormet producing mycorrhizal fungi species, that has proven established relationships with the tree species, like apples and morels. So you could help your trees grow better through additional mycorrhizal symbiosis, but also have another potential annual crop. The morels are a bad example, because they wouldn't fruit much untill your tree was sick; however, trees like hazel nuts are. Since you could grow truffles in symbiosis with hazel nuts.
A few more things to consider, hopefully not to much at once...lol!
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