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  • From: "Jack Rowe" <jackrowe@tinyorb.net>
  • To: "permaculture" <permaculture@lists.ibiblio.org>
  • Subject: Re: [permaculture] N in arid soil
  • Date: Fri, 18 Dec 2009 10:21:10 -0700

Rain,

I have a similar situation in northern New Mexico, US, as regards low soil moisture -- low precip, high evap. We try and keep our mulches replenished (materials are not overly plentiful because of the aridity) and rather than composting in piles, we put all materials on the garden as mulch. A lot of N is released by the mulch during its breakdown/composting process, if this happens in place on the soil the N will be taken up by microbes to a very large extent (this is true in humid climates as well, though muches need to be added more often and in thinner layers to avoid waterlogging). No doubt some N is 'lost,' but the earth being a closed system (if we include the sun and ignore meteorites/dust) the N will be used somewhere by some grateful plant. Nothing is 'lost' on our planet, this is the big problem w/ how we 'dispose' of the things we don't like -- it's a shell game where all the shells get smothered in poop while the gardens go hungry.

We also store water in ferro-cement cisterns in an attempt to have water to keep the soil moist during the dry season to the degree possible. And we accept that plants will be tending toward some dormancy during the dry period (which for us occurs in spring, not 'convenient' from a gardening point of view, but w/ a little help the plants bide their time until the water comes). Using drip under the mulch minimizes evap and also minimizes salt-buildup, which is a perennial problem in arid soils and difficult to fix once it happens. Here again rainwater is very valuable as it contains no salt; gypsum (calcium sulfate... sulphate?) helps release the salt which is otherwise very tightly held by ionic bonds in the soil (assuming presence of clay and/or humus).

ANY salt in the soil (free or bonded) exerts an osmotic pull on the soil's water, making it that much more difficult for plants and microbes to use this water. Even when gypsum releases the sodium ions, it's hard to find enough water to wash the salt away and it continues to exert its pull on soil moisture. If you're using well water, this problem is a virtual certainty. I've seen salt shut down a soil in 3 - 4 years, esp. when greywater is included (extra salt from several sources including urine, bodies being washed, cooking). Greywater should always be applied sub-surface in arid areas, if it is used at all. We put our greywater into a basin planted to salt-loving trees, in our case Siberian elms, well-hated but good mulch producers, kept 100 feet from gardens they are useful (very aggressive roots).

And pardon me for saying so (just in case you're squeamish), but if you're willing to pee in a bucket you can keep a substantial amount of garden area well-supplied w/ soluble N (1 pee: 15 - 20 water or about a quart per 5-gallon bucket, this ratio will vary w/ how much water you drink) and a happy dose of K as well. The soluble N in urine will be available to soil microbes and plants' roots even when the general microbial population has slowed nutrient cycling due to dry conditions. Using urine, you will add slightly to the salt problem so extra attentiveness is called for (this is true for manures as well).

Sorry for the silence on your on-topic post, we've all been ardently discussing who shall be called Right and who shall be called Wrong. Me... I'm Wrong, but warm and over-fed, so for some reason I still have this stupid persistent grin on my face.

Jack

----- Original Message ----- From: "Rain Tenaqiya" <raincascadia@yahoo.com>
To: <permaculture@lists.ibiblio.org>
Sent: Wednesday, December 16, 2009 4:17 PM
Subject: [permaculture] N in arid soil


In permaculture, part of our goal is to keep nutrients, energy, and water cycling within the biological realm as much as possible. Composting, slashing carbon and dynamic accumulator crops, and the use of animals in systems are ways of speeding up nutrient cycling and concentrating carbon and nutrients into our production systems. During a dry period, the cycling slows down as organic matter and manures are not able to break down and return to the system. Unless we apply water to these materials, they will pretty much remain unused, losing nitrogen to the air, until it starts the rains return. This is the challenge that I am concerned about in the Mediterranean climate that I live in. Short of collecting all the material, composting it in irrigated piles or pits, and redistributing it, I am resigned to lowered productivity in my systems, and slower soil building.

Rain



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