Thank you Eric for helping me elaborate on this point because I imagine others on this list also misinterpreted the situation as you have.
We must be very careful to distinguish between dry sandy SOILS and dry CLIMATES. Dry sandy soils in humid climates (which is Cory´s case in Florida, unless the cliamte there has changed since I lived there) need totally different strategies from sandy soils in dry climates, which is the case of my present farm. So I will elaborate on both, getting around to polycultures in both...
The key is whether we have enough humidity for good decomposition of organic amtter. If we do, the very best strategy for sand is to pile on the organic matter. You may have to kick-start it with compost or manures or compost tea, but once it gets going these soils are extremely active- you can almost hear them slurp at night! The most difficult thing then is to keep supplying them with organic matter, the absolutely best being the ends of tree branches:
We can make reallly really dense plantings in this kind of soil ( only managing light requirements), something like one plant every ten centimeters. The vast mat of roots will help build the soil up at incredible speed. There are lots of already-existing polycultures appropriate to this kind of situation. (Don´t forget to use castor, great nitrogen source and boron accumulator, which could be a limiting factor in sand.)
Compost is not necessary here- it would be like opening baby food for a child which has teeth( exception being at the beginning).
Raised beds work fine here, especially if you fill up the valleys between beds with organic material. It is important to plant mulch plants which resprout easily- hibiscus is great for this, and makes the project beautiful. Our "forest gurú" Ernst Gotsch has even used it in commercial fruit agroforests.
When working in dry climates, where there is NOT enough humidity to decompose the organic matter, it is a whole nother ballgame, as they say back in the old country (USA).Then you must go down as Eric says, and use pre-digested organic matter, such as composts and manures. In fact the bacteria in the cow´s rumen substitute for the soil bacteria, which are inactive a good part of the year.
Mulching can actually be a detriment if you put on too much or the wrong type- something I had to learn the hard way.
Polycultures? I am still experimenting with them. During the rainy season we have sucessfully worked with rather dense plantings. In the drier part of the year, or in drier years I am not yet sure how much we can push it. It seems to be important whether the plants are "cool" or "hot" as the local farmers say. "cool" being those plants which contribute humidity to the system, susch as purslane and opuntias. "Hot" would be those plants which grab the humidity for themselves, such as mesquite and sisal and some of the annual weeds.
The organic matter often needs to be incorporated into the soil otherwise it just oxidizes - am still experimenting with this, too, so may say differently next year. We would never have to do that in sandy soils in humid climates, although a French Intensive system would be a great way to start!
As to trees in trenches, my very best garden trench has a whole tree buried in it! It helps the trench not go anaerobic, which can be a problem in this form of farming. Of course I don´t us JUST woody material in such a trench , but then nitrogen is easy to come by to compensate the carbon. We also add charcoal a la "Terra Preta de Índio" to help keep the micro -organisms ( even more important in humid climates!)
FINALLY - I have three practically contiguous properties, totalling some 50 acres. In spite of their proximity they have totaly different vocations, personalities, soils needing radically different strategies. So There is no way that one can avoid the learning curve. One has to take the time to learn to dialogue with the system. Once you do, it can "tell" you what needs to be done....If I hadn´t arrived here "thinking I knew about agroecology" my progress might just have been quicker, if I had just got my information directly from the system...
--- On Wed, 2/18/09, Eric J. Frank <ericjolen@...> wrote: From: Eric J. Frank <ericjolen@...> |
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