livingontheland@lists.ibiblio.org
Subject: Healthy soil and sustainable growing
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- From: "Douglas Willhite" <drwillhite@earthlink.net>
- To: "Douglas & Hillary Willhite" <drwillhite@earthlink.net>
- Subject: [Livingontheland] soil fertility
- Date: Sun, 3 Jun 2007 10:51:56 -0700
In my years as an agriculture teacher, a science teacher, and a farmer,
I've
noticed a great deal of misinformation out there about animal manures and compost. Many believe that you can turn a few animals out in a pasture and the animals, by means of their manure, will make the soil more fertile without any help from the feed store. . And when it comes to compost, magical qualities are sometimes attributed to it that can't be supported by the laws of science. A popular book by John Jeavons, "How to Grow More Vegetables . . . ", advocates growing "compost crops" on garden beds, composting them, and then returning them to the beds with the expectation that soil fertility will be sustainably enhanced. For years I've let the idea of a "closed system" slide without challenge but at this point in time I feel compelled to come out of the closet. As we know, grim times may not be far ahead and gardeners who anticipate getting a good portion of their food from their gardens need to be working with a full-deck of information. Whole systems agriculture advocates an "open system" to build and maintain fertile soil. The principal vehicle for this, in a post-carbon world, would be to gather mulch from land surrounding one's garden and bring it into the garden for mulching the beds. My very rough calculations for the amount of land required for this go like this. . . --1/10th acre of intensive bed will supply the subsistence caloric requirement for 1 person, harvesting 2 crops per year. 1/5th acre would be required if the climate is such that only one crop can be grown. --Fertility would be enhanced and maintained by gathering mulch from an additional 1/10 acre to one acre of less intensively used land, say from urban and suburban landscapes, pastoral or wildlands. Let me review the scientific principles that apply here. . .. We have, in the first place, the Law of Conservation of Matter. This says that matter, and more specifically elements, cannot be created or destroyed [at least in one's backyard] and that matter can only be reorganized into various compounds. This means that nothing comes out the back of an animal that doesn't go in the front and nothing comes out of a compost pile that didn't go into it as far as the 16 or so essential plant nutrients are concerned. Then we have Leibig's Law of the Minimum. This states that plant growth will be limited by the least available nutrient and it further states that one nutrient element cannot substitute for another. My soil here in Madera, for example, has an a critical shortage of potassium but this will not be made up for by the abundance of phosphorus. Plant and soil scientists believe that, in the end, potassium will probably be the most critical element in maintaining soil fertility. Lastly there is the Law of Entropy which could be thought of as "the disorganizing force" that always pulls on all that is organized. Each time the elements of life, that is the 16 or 20 elements required for plant and animal life, are assembled into plants, then reassembled into animals, then remineralized back in the soil, there is a loss. In farms in gardens this "leakage" takes place by leaching and erosion whereby the elements become widely disbursed and unrecoverable. [Liquid fuels are made up of highly organized molecules of carbon, hydrogen and oxygen but combustion "disorganizes" them into carbon dioxide and water with the attendant loss of the sun's energy that went into them.] As we know, it will take a very long time for them to get reorganized back into petroleum based fuels. In the end, agricultural sustainability will be limited by the rate at which rocks can be weathered into soil and the minerals in those rocks made soluble. This is why intensive beds alone cannot be relied upon to be sustainable regardless of one's skill at making compost. A considerably larger area is required to make the minerals in rocks available to plants and I suspect that even 1 acre per person may not even be enough. In discussing these ideas with Dr. James Farrar, Plant Science Department Head at California State University, Fresno , he commented as follows. . . "You are correct that composting will not add any minerals that are not present in the animal or plant material. As you know, composting can change the nature of the organic material and the population of microorganisms present in the compost. "The only mineral exception is that it is possible to incorporate nitrogen into the system through the use of legumes. The downside is that that legumes--Rhizobium symbiosis--is driven by low nitrogen availability so you have to start with a nitrogen depleted soil in order to get much benefit. There are also free-living nitrogen fixing bacteria that we are learning more about." Please visit our website at . . . http://www.wholesystemsag.org for more good ideas about growing food in the difficult times. A global food crisis may be at hand. with the USDA predicting only a 53 day supply for the 2007 crop year--half the supply of 1999 and the lowest ever since records have been kept. Food production per person has been declining for years and the fact that huge amounts of land are now being used for growing biofuels puts the Wolf right near the door. Expect substantial food price increases soon if you haven't noticed already. In addition to honing up on gardening knowledge and skill I recommend laying up a good supply of dry beans and peas. Read more in the Food Security section of our website. Good wishes and good growing, all John Warner Madera Whole Systems Agriculture near Fresno, California No-tractor, no tillage market growers since 1996 http://www.wholesystemsag.org |
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[Livingontheland] soil fertility,
Douglas Willhite, 06/03/2007
- Re: [Livingontheland] soil fertility, TradingPostPaul, 06/03/2007
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Re: [Livingontheland] John Warner,
Ken Hargesheimer, 06/04/2007
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Re: [Livingontheland] John Warner,
TradingPostPaul, 06/04/2007
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Re: [Livingontheland] John Warner, etc.,
E. E. Mitchamore Jr, 06/04/2007
- Re: [Livingontheland] John Warner, etc., TradingPostPaul, 06/04/2007
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Re: [Livingontheland] John Warner, etc.,
E. E. Mitchamore Jr, 06/04/2007
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Re: [Livingontheland] John Warner,
TradingPostPaul, 06/04/2007
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