Hi Bob >Hi Keith, > Re the nitrogen issue:
Or non-issue? >there is another way in which >exhausted land can be rejuvenated. Crop rotation is the biblical method Not just a biblical method, it's worldwide, impossible to say where it originated - no single place would probably be the answer. >whereby an area of land is left fallow each year and "rotated" year by year >through a preset planting and fallow cycle (generally fallow every fourth >year). The nitrogen level in the soil can be augmented with the planting of >any legume or pod-bearer e.g. peas, beans, alfafa, lucerne etc. during the >fallow period. Leguminous plants, such as the above, process nitrogen from >the air and transfer it to their roots. In the case of peas, beans and other >food legumens the crop is harvested and the roots and stalks left to rot. >Non-harvestable legumes e.g.lucerne, gorse are ploughed in. In all cases the >nitrogen rich roots are left in the ground where they decay rapidly and >release their nutrients in time for the next year's crop. Rotation of various kinds is an essential part of a sustainable system, but on its own its not a very efficient way of rejuvenating exhausted land, especially when it focuses mainly on nitrogen levels. These are mainly green-manuring techniques; usually the plants are ploughed in just before flowering, when there's a maximum of soft, green tissue that's indeed nitrogen-rich, but has little or no effect on the humus supply, nor its condition, which is much more important. Weather conditions are suitable for humus-building by green-manuring maybe once in seven years, and it's not a reliable average. Again, leguminous plants do indeed "fix" atmospheric nitrogen in their roots (and not the only things that do so), but the more fertile the soil the more nitrogen they fix, and in poor soils it's often not very much. Rich, fertile soils also have hosts of free-living microorganisms, e.g., Azotobacter, that do the same thing as the rhizobia strains do with legume roots. Releasing nutrients in time for next year's crop also isn't quite so simple. Again, it's not simply a physical or chemical process. Most soils have two nitrogen "flushes" a year, with large amounts of nitrogen made available to plants by the soil microorganisms from the available resources, if any (soil organic matter in various states). The art of it lies in catching these flushes and capturing the nitrogen they provide in growing crops. All of this leaves out a more important soil process for plant growth, mycorrhizal activity. See: Trees and Toadstools by M.C. Rayner, 1945 http://journeytoforever.org/farm_library.html#rayner "Simply put, in a healthy soil plant roots are invaded by a friendly soil fungus; the fungus actually feeds the plant, and in return the plant feeds the fungus the products of the green leaf which the fungus is unable to make for itself." At least it should be a more important soil process for plant growth, but in soils abused by chemical fertilizers the vital fungi that do the work are usually either dead or ailing. Anyway, mere crop-rotation and green-manuring do little for mycorrhiza. That needs humus-building. Also, there's no need for the fallow, that's easily sidestepped. Once you add livestock to the equation, especially grazing livestock, it becomes a quite different matter. Now your "fourth-year" fallow can become the most productive part of the whole cycle - and at the same time it creates huge amounts of fertility, more than enough for the next three years of crop production at least. This is called ley farming - the temporary grass "ley" is the "fallow", used for heavy grazing. The grass isn't just grass, it's up to 25 different varieties of grasses, legumes, and deep-rooting herbs (aka "weeds"). The basis of this is the Clifton Park system developed by Robert Elliot. You can read about it here: http://journeytoforever.org/farm_library/elliot/cliftonToC.html Clifton Park - Contents I'm currently scanning more work on this, especially work done at Aberystwyth by George Stapledon. You just won't figure this out if you focus on the mechanics of it and the chemical nutrients, it doesn't work that way. This is from our website: "Ley Farming" by Sir R. George Stapledon and William Davies, 1948, Faber & Faber, London. Sow a piece of land with a good pasture mixture and then divide it in two with a fence. Graze one half heavily and repeatedly with cattle, mow the other half as necessary and leave the mowings there in place to decay back into the soil. On the grazed half, you've removed the crop (several times) and taken away a large yield of milk and beef. On the other half you've removed nothing. Plough up both halves and plant a grain crop, or any crop. Which half has the bigger and better yield? The grazed half, by far. "Ley Farming" explains why "grass is the most important crop" and how to manage grass leys. Leys are temporary pastures in a rotation, and provide more than enough fertility for the succeeding crops: working together, grass and grazing animals turn the land into a huge living compost pile. Stapledon draws on the work of Captain Elliot of Clifton Park, whose work with deep-rooting leys was the culmination of hundreds of years of development in grass rotation farming. http://journeytoforever.org/farm_pasture.html Pasture for small farmers: Journey to Forever This isn't the only way of doing it, there are plenty of others, but you can see from this why rotation and green-manuring alone might not accomplish very much. That would be classed with the first of the three types of organic growing: organic by neglect, low-input, low-output, medium to poor quality produce. Not true organic growing at all. Next comes organic by substitution, which uses the industrialised methods but substitutes inputs of organic origin - high-input, medium to low-output, medium to poor quality, also not true organic growing. Then comes organic by design, low-input, high-output, high quality. This is true organic farming. It uses the kind of proactive management that prevents problems arising in the first place, by dealing with the causes (eg poor, unbalanced soil), rather than the symptoms (eg, the pests that attack sick plants grown in poor soils). It's a bit like the kind of crisis management that would deem the development of an actual crisis to be a failure of management, or the military strategy in "The Art of War" that sees the need to fight a battle as a failure of strategy, no matter who "wins". Anyway, it's easy to do, and as Kim said, as millions of people say, it's much less work. It's the method that's most appropriate to the production of biofuels crops. It's true Appropriate Technology in fact. Regards Keith >Regards, >Bob. ------------------------ Yahoo! Groups Sponsor --------------------~--> Make a clean sweep of pop-up ads. Yahoo! Companion Toolbar. Now with Pop-Up Blocker. Get it for free! http://us.click.yahoo.com/L5YrjA/eSIIAA/yQLSAA/FGYolB/TM --------------------------------------------------------------------~-> Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://infoarchive.net/sgroup/biofuel/ Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/biofuel/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
