I live on sand. My under foot is of the same substance as the great sand islands of South East Queensland. Here there is no run off: water seeps into the sand like a thirsty sponge to the water table below as soon as it precipitates.
Growing stuff on all these granules demands creative thinking.
I began my gardening life here with the notion that I needed to perch my homemade soil -- humus type stuff -- on top of the sand. So I used a lot of sheet mulching techniques to lay down a productive layer while I built up my soil out of grass clippings, horse manure and seaweed.
While this activity has produced a rich sandy loam from a productive lasagna effect, once the water passed through this top blanket, there still remained sand all the way underneath.
It was still a water seepage freeway...
Nonetheless, my homework included the brilliant synthesis offered in Brad Lancaster's books, Rainwater Harvesting for Dylands and Beyond.
I don't really suffer from dry landness as I live in the coastal sub tropics, but I was interested in ways of means of hanging onto the water that passed so quickly through my soil. Hanging onto moisture is a dry land challenge too. Because of the extremely porosity of sand, it's of little consequence if you remodel the land contour to create gutters, swales and such.
So many sand dunes are still going to be so many sieves.
Nonetheless, through Lancaster, I began to experiment with vertical mulching . This means that as well as spreading mulches over the surface of the soil, you dig trenches and fill them with mulch.
At first I used this approach to partner my fruit tree saplings when I planted them: a one foot deep trench about A4 size. I'd dig a hole and throw in plenty of waste paper over which I layered some grass clippings. I'd then run grey water into these holes for irrigation.
It got so that any time I planted anything I'd also dig a little hole next door and fill it with cardboard and newspaper just so that the plant had a spongy water tank it could draw on when thirst kicked in. Since I've been monitoring this activity it has become very clear that these holes do indeed retain a lot of water when the surrounding areas dry out. They also quickly begin to break down and a lot of biological activity kicks in among the layers of paper.
I thought that I was onto something and have begun to dig trench gutters along new garden beds.
Junk Mail Harvesting
Here we get delivered two local newspapers per week, already firmly rolled up or folded into a shapes that suit my shallow trenches. We also must be the centre of a major outbreak of junk mail with almost daily drop offs of various catalogues and promotional materials.
All this I bury.
I even trawl the neighborhood harvesting all the junk mail -- and preferably newspapers -- that here is never placed in letter boxes but is thrown on nature strips and drive ways often from the windows of passing cars. I have mail enough on hand to wallpaper acres because people just let so much of this junk accumulate at the doorstep.
While I prefer a tasty bit of brown cardboard ( snaffled from the skip at the local pub or begged from neighbours) to feed my garden I am not so concerned about heavy metals in some inks used in junk mail, because we're talking low dosage. And besides, the majority of inks nowadays are soy based because of economic reasons. The chemical make-up of non-glossy colored ink seems to be vigorously debated but really in the large scheme of things who cares when supermarket food packaging comes in such exotic chemical mixes?
Each week I get delivered close to half a kilogram of junk papers, so I use it all: I can't get enough of the stuff.
The end result is that I have rivers of junk mail and newspaper running hither and yon where fancy dictates. There is so far no hint of nitrogen leeching depriving plants of sustenance because these trenches are so narrow and shallow and are usually separated from any planting by at least 15-20 cm. Because the paper is rolled up and folded it breaks down in its own god time. The trenches perform more like gully traps -- musty, yucky and moist -- attracting a lot of biological activity from what was seemingly sterile sand: initially termites and grubs , then earth worms. They are little micro climates -- cavernous patches of rotting activity that seem more creature busy than the sheet mulches I use atop the garden beds.
The hypothesis that I'm working from is that these trenches filled with mulch-matter, store water which is available to the plants in the vicinity as required. So I'm assuming that roots will turn toward the trench or rely on osmotic permeation to drink.
While tree specialist-- arborists -- have often utilized trench mulching to get water to roots deep in the soil , the technique is now a Permaculture standard with banana or pawpaw circles. The principle can be applied more freely.
I find that a slow irrigation of the trenches leads to water absorption along a row of paper. Its also very easy to monitor if the area needs watering: you need only stick in your thumb to test moisture content.
This time of year I am getting no grass clippings (because the lawns don't grow so fast) so my mulch addiction is being fed with paper.
