From bluestem@webserf.net Thu May 20 09:24:33 1999 Date: Thu, 20 May 1999 10:07:18 +0100 From: Bluestem Associates To: "sanet-mg@ces.ncsu.edu" Subject: Nitrogen in organic agriculture I should think if any group would understand that use patterns and results would be all over the map, it would be *this* one. That said, a few observations. Many (perhaps most) of the organic farms that I inspect do *not* capture enough nitrogen to maintain a productive system over the long term. In that respect Avery and some of the other naysayers have a valid *empirical* point. These farms, however, are almost always short of nitrogen owing to poor nitrogen management (insufficient N fixation, manure management problems, etc.). It is entirely possible for a well-managed organic farm to capture all the nitrogen needed for "high-yield" production. In fact, it is not at all uncommon for an organic system to become too *rich* in nitrogen one or two rotation cycles after the transition, at which point the grower shifts to mixed hay (rather than straight legumes) and things settle down. Virtually all farmers (organic and otherwise) neglect the valuable role played by molybdenum in improving the efficiency of nitrogen capture. With well-considered additions of molybdenum, it is quite possible to capture more solar energy (through increased yields) than can be released from an equal weight of uranium via nuclear power. A few grams per hectare is usually all that it takes, added with inoculant at seeding. This because the nitrogenase component of the rhizobial nitrogen fixation reaction is dependent on an Fe-Mo protein, with moly being the limiting factor. Editorial comment about Chilean nitrate --- if organic is to allow any soluble nitrogen at all, it should be in the form of ammonium sulfate, not as a nitrate. Every other nutrient sulfate is already permitted, and AS is much better for soil microbes than the nitrates. Also, any idea that an organic inspector can determine the difference between 10-20 kg/ha nitrate and 50-60 kg/ha or even more (split apps) is ... pure fantasy. I have to chuckle when the naysayers criticise organic production as "inefficient" when their Farm Bureau buddies routinely knife in 400 units of anhydrous per acre every autumn and then have to come back over their corn with liquid 28 the following season just to make sure they have "enough." Conventional American agriculture is "efficient" (I suppose) in the same way as the American consumer economy. You can jump into a 2-ton SUV and drive it three blocks to pick up a 2-ounce packet of razor blades, and marvel at the "efficiency" of it all--- and look down one's nose at the scruffy unshaven neighbours -- but it is tragically laughable to conclude from that situation that walking and bicycles are inadequate. Bart Hall Lawrence, Kansas To Unsubscribe: Email majordomo@ces.ncsu.edu with the command "unsubscribe sanet-mg". If you receive the digest format, use the command "unsubscribe sanet-mg-digest". To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command "subscribe sanet-mg-digest". All messages to sanet-mg are archived at: http://www.sare.org/san/htdocs/hypermail From danamex@mail.internet.com.mx Thu May 20 23:40:16 1999 Date: Thu, 20 May 1999 14:08:21 -0500 From: Ronald Nigh To: sanet-mg@ces.ncsu.edu Subject: Re: Nitrogen in Organic Agriculture [ The following text is in the "iso-8859-1" character set. ] [ Your display is set for the "US-ASCII" character set. ] [ Some characters may be displayed incorrectly. ] Dear SANET, Excellent post , Bart. >It is entirely possible for a well-managed organic farm to capture all >the nitrogen needed for "high-yield" production... Amen! It is not only possible, it is absolutely necessary! >Virtually all farmers (organic and otherwise) neglect the valuable role >played by molybdenum in improving the efficiency of nitrogen capture...This because the >nitrogenase component of the rhizobial nitrogen fixation reaction is dependent on an Fe->Mo protein, with moly being the limiting factor. And of course the exact same nitrogenase (only one has eolved) catalyzes free-living N fization as well. If moly is present, however, we should attend the other factors limiting microbial N fixation (energy is often the next one; Ca or P can also be a problem) and the factors that limit stabilization of that N in organic forms (i.e. avoiding nitrification, etc.) This is the essence of N management. All soluble salts of N, including Ammonium Sulfate, inhibit microbial N fixation, a very good reason to avoid becoming dependent upon them. Regards, Ronald Nigh Dana, A.C. Mexico, D.F. & San Cristóbal de Las Casas, Chiapas Tel. y FAX 525-666-73-66 (DF) 529-678-72-15 (Chiapas) danamex@mail.internet.com.mx To Unsubscribe: Email majordomo@ces.ncsu.edu with the command "unsubscribe sanet-mg". If you receive the digest format, use the command "unsubscribe sanet-mg-digest". To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command "subscribe sanet-mg-digest". All messages to sanet-mg are archived at: http://www.sare.org/san/htdocs/hypermail From sgroff@epix.net Thu May 20 23:41:15 1999 Date: Thu, 20 May 1999 22:24:16 -0400 From: Steve Groff To: Pat Elazar Cc: Roberto Verzola , lonrom@hevanet.com, sanet-mg@ces.ncsu.edu Subject: Re: No-till (Formerly FW: Farmers Part of the Global WarmingSolution) Pat Elazar wrote: > > Who have you seen or heard campaigning against tillage? Of course companies who manufacture herbicides will promote them to no till farmers, but as you see below, long term no till will reduce the need for herbicides. It certainly has on my farm. If you talk with any soil scientist, he will tell you that most tillage has a detrimental effect on the soil. Tilling the soil might benefit the farmer in some way, but not the soil and the critters who live in it. > the no-till/low-till guys who'd been doing it for a while generally used less > chemical than anybody else. If they survived the first couple of years, they > learned how to walk their fields, map their fields & widen rotations to reduce > weed problems systemically. The no-till guys also used half-rates, one third > rates & spot applications when they did spray. They also chose more competitive > varieties & tinkered combine settings to maximize crop residue (we usually call > that mulch on this list). After 10 years of no-till, they usually had more > organic matter, less weeds, less disease problems than their neighbours & maybe > even a few worms! > > have > Alot of farmers (especially the conventional) are aware of this and are doing something about it now. I've found the detrimantal effects of tillage to be an issue that a good many sustainable farmers ignore. The moldbord plow has caused significant damage to the quality of soil. Steve Groff -- "Enhancing the Environment" www.cedarmeadowfarm.com Cedar Meadow Farm 679 Hilldale Rd Holtwood PA 17532 USA Ph. 717-284-5152 To Unsubscribe: Email majordomo@ces.ncsu.edu with the command "unsubscribe sanet-mg". If you receive the digest format, use the command "unsubscribe sanet-mg-digest". To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command "subscribe sanet-mg-digest". All messages to sanet-mg are archived at: http://www.sare.org/san/htdocs/hypermail From danamex@mail.internet.com.mx Sat May 22 18:32:09 1999 Date: Fri, 21 May 1999 13:25:49 -0500 From: Ronald Nigh To: sanet-mg@ces.ncsu.edu Subject: Nitrogen in Organic Agriculutre [ The following text is in the "iso-8859-1" character set. ] [ Your display is set for the "US-ASCII" character set. ] [ Some characters may be displayed incorrectly. ] Bart wrote: >Most non-symbiotes would be doing very well to fix 50 kg/ha nitrogen. >Except in fairly anaerobic environments -- rice, for example -- I >wouldn't go out of my way to encourage them, to say nothing of *add* >them to the soil. They are, however, a delightlfully fascinating >component of creation. > Well, I know this is conventional wisdom, that the non-symbionts are not worth the trouble. In my opinion, however, this is an error. The Cubans have some interesting experiences with Azotobacter achieving higher levels than this. There is also some work in the tropics (Brazil) that suggest Azotobacter can be a significant N-fixer under the right conditions. Also, there is something else to keep in mind: 50kg/ha of N fixed in the context of a complex soil microbiology and good soil structure can have a dramatically different effect on the soil and on crop productivity than does an equivalent or greater amount of soluble N salts or anhydrous ammonia. In an organic soil it just isn't necessary to add such high levels of N as are common on some conventional farms, a large percentage of which ends up in the drainage. Also in the humid tropics we are beginning to suspect that N-fixation by bacteria on the leaf surfaces could be important, in which case Mo given as a foliar fertilizer could be very beneficial. Experience so far seem to bear this out. I don't know how relevant this source could be in more temperate or drier areas. A friend of mine doing reserarch in Oaxaca has found 15 species of bacteria, several of them N fixers, in the exudate from the adventitious roots of Indian corn varieties. This is not precisely a symbiosos of the rhizobium type but is probably part of the rhizosphere microbial populations that feed on carbohydrates the corn plant releases into the soil for that purpose. The point is there is a lot more to N-fixation in agriculture than Rhizobium and there is even more to it that we don't know about. I say don't write off the non-sybionts too fast. They have a great potential to contribute to more adequate N management in future agriculture. I remember reading a few years ago that the nitrogenase enzyme was remarkably uniform in different organism. It has two metaloproteins, one with Moly, Iron and Sulfur and the other with an Fe-S group. Its uniformity, according to what I read, suggests that it evolved only once in the history of life. There may be more recent research I am unfamiliar with. I recall that V can substitute for Mo in some metaloproteins but I thought the enzymatic activity would be considerably lower. I remember some speculation of possible V-based N-fixation systems and would like to have any references on that. That would be very interesting. Finally, we should always remember that N-fixation is only one link in the nitrogen cycle, albeit a critical one. But proper N management means paying attention to other important links, to create conditions that retain organic N in the soil biomass as much as possible. Regards, Ronald Nigh Dana, A.C. Mexico, D.F. & San Cristóbal de Las Casas, Chiapas Tel. y FAX 525-666-73-66 (DF) 529-678-72-15 (Chiapas) danamex@mail.internet.com.mx To Unsubscribe: Email majordomo@ces.ncsu.edu with the command "unsubscribe sanet-mg". If you receive the digest format, use the command "unsubscribe sanet-mg-digest". To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command "subscribe sanet-mg-digest". All messages to sanet-mg are archived at: http://www.sare.org/san/htdocs/hypermail