There is a system out there called the Mittleider Gardening Method [google]. I've not had the time to look into it in depth, although I have taken a close look at the irrigation aspect of the method and found it promising enough to start trying it out. This method incorporates some sort of fertility treatment with which I have not familiarized myself.
I imagine their nutrient content would be less if they are grown in a medium without any nutrients. It's like the commercial tomatoes that are grown in sand in Florida, they basically have no nutritional value, just propped up plants on fertilizer. I think that living soil is really beneficial to the health of the food we eat. But, maybe it's not a big deal.
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The soil I have is 99% sand. I don't add synthetic fertilizers yet I still obtain a yield.
I can add inputs with grass clippings, compost, leaf mold, sticks and logs, and wood chips being available in good amount at no cost.
This Mittleider method employs a feeding/nutrient treatment which I need to take a closer look at. I'm sure it can be done organically, with liquid grass clipping fertilizer, compost tea, or some sort of blend. This is not in the highest spirit of permaculture, but it's surely not chemical growing.
A critical issue I face is the inability of the sand to hold water. Drainage combined with the heat of the Florida sun dries the soil to dust. I don't know how grass grows.
My attempts with hugelkulture, deep mulch, and massive amounts of inputs are proving highly effective in reducing my need for irrigation, but in the cool season (October through March) there is little rain. I can still raise crops, however without irrigation my yields will be significantly reduced.
In my experience, every plant has conditions which will produce a great yield. A One-Size-Fits-All approach to gardening isn't going to work for everything. Berries like more acid. Potatoes thrive in moisture, even with poor nutrients but if you give them nutrients they perform magically. Peppers want it hot. Beets want whatever I'm not offering-I can't grow a beet. Rosemary is indestructible. Broccoli is interesting in that it works like a pump. When the plant is done I cut off the growth to leave a stump. The roots keep on moving water from a foot down up to the surface where it runs back down to the soil, keeping the surface moist. Starting lettuce after broccoli does much better because the roots are shallow and that extra surface moisture gives them a boost.
Perhaps the greatest advantage to the sand is found in root growth. The sand is able to give way to the roots which can grow extensively in search of nutrients. In order for the roots to grow so well, there needs to be ample moisture and something to eat. Back to the debate over feeding the plants vs feeding the soil. I'm finding a deep and diverse mulch to be serving my needs well. As the mulch breaks down, the nutrients percolate down into the soil. Material with a high lignin content (sawdust, wood chips, leaf mold) supports the fungus. It's that fungus that makes nutrients available and moves it around to where it is needed.
Everything works together. Sand and sawdust is a start. Add more features to the method and the results will improve.
Seed the Mind, Harvest Ideas.
Leaf Mold! By all means, pile it on. I can't say enough good about it
Humans can get by on a diet of milk and potatoes. Together they provide a complete protein. Although you won't die of starvation, there's not much vitamin C...perhaps scurvy will become a problem. A variety of foods will offer more of those vitamins, minerals and phytochemicals the body needs. Plants are no different, nor are the microbes in the soil.
We can not live on bread alone. Plants can not live on N-P-K alone.
Too often I see and here growing systems that reduce complexity to barebones necessities. The County Extension Service is notorious for helping people 'improve' their soil by prescribing how much synthetic fertilizer and lime to add in order to bring the soil up to recommended levels. Have a look at the Garden Picture Exchange and see if plants are thriving.
Simplicity can grow a plant.
Complexity will grow abundance and nutrition in great diversity year after year.
Please don't misconstrue my zeal as bashing the idea of sand and sawdust. There are places in the world where it's the only thing available besides concrete and steel, which are VERY hard to grow anything in. In the absence of deep, rich, well drained loam in a tropical environment, using what resources are available and trying is better than doing nothing. From trying come learning. Learning develops an understanding of the myriad ways life works to promote more life.
Seed the Mind, Harvest Ideas.
Here is the video on the fertilizer mix, basically a bulk version of miracle grow. You can do the same thing with rock dust, compost and comfrey tea--if you do the chemistry and math.
Sweet potatoes need lower nitrogen to set tubers. It is easy to over-fertilize them--the sawdust helps to bind up extra nitrogen.
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