Cost / lb to "grow your own nitrogen"?
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Legume Plowdown - (or Soil Health 101)
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Can't quantify something like that. You can try, but it would be very difficult. A good crop of clover can fix over 100lbs of N per acre. So I would say very cheap.
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How seriously have we considered the challenge of growing a "crop of nitrogen"? How much research has gone into maximizing yields?
How do you establish the value of the nitrogen? Is a pound of nitrogen from green manure equivalent to a pound of nitrogen from anhydrous or urea, or is it more valuable? Does a pound of nitrogen from green manure give you more of a "kick" than synthetic fertilizer and if so then why?
Is nitrogen the only benefit from green manure plowdown? I don't think so. What about soil organic matter? What about soil structure? What about the water holding capacity of the soil?
Perhaps some areas of the country are more suited to green manure than others. What factors are most important in assessing the effectiveness of a green manure rotation? Average annual rainfall? Soil type? Temperatures? Soil pH?
Some of these questions have probably been answered in much more detail than I am aware of. I am a novice when it comes to soil science. I am very open minded. I am willing to learn. Most of all I am looking for solutions to the crisis in agriculture.
I suspect that we farmers have much opportunity to impact our own future. Some parts of that solution are entirely within our own control. So parts of the solution require collaboration and cooperation. I don't think that we should throw cold water on any idea unless there is a body of proof that it is unworkable. Even ideas that were tried and didn't work in the past may work now with new technology or different circumstances.
If green manure plowdown can be considered a "crop" then what is stopping us from doing it in 2006? Is it a lack of cash flow? That is the response I get most often when I talk to farmers about this idea. They say that they need each and every acre of their farm to produce revenue every year. Perhaps this is a situation that requries some government intervention.
The government has put $750 million dollars on the table in an ad hoc program right now. What if there was a small "string" attached to that money? What if the government said for each $100.00 you receive in this ad hoc program you must plant one acre to a green manure crop. That would force 7.5 million acres into green manure this year. That is equal to about 15 percent of Western Canada's cultivated acres. At one tonne per acre of grain it would represent 7.5 million tonnes less grain going into the export market. I know that is a small percentage of world production but the world surplus of grain is not really all that large. It is just large enough to depress prices. The world has eaten its way through more wheat than it has produced for four of the last five years. I think that 7.5 million less acres of grain available for export from Canada would have a significant impact on prices, particularly if the program were extended for three or four years.
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I'll take a stab at some of your questions, Vader. A lb. of N is a lb. of N regardless of how it is created.
Re: Soil organic matter, No till farmers realized long ago the value of organic matter in their soils. In the last 20 years I've doubled the organic matter in my soil, from 2% to 4%. I shudder at the thought of utilizing techniques that involve tillage.
I am interested in a green manure crop if it could be sprayed out in July(of the year it was planted) & I'm able to seed directly into it next spring. Clover, I think, requires 2 years before it fixes any N. Correct me if I'm wrong.
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I think chemical companies have done a fine job of making us fear tillage. Yes, half and half 5 passes of summerfallow with a cultivator until the land is black seriously hurt our soil over the years. We had our land blow away and created hard pans that roots struggled to break through. And the result was a decrease in organic matter.
Responsible tillage, however, would not have had those damaging effects. What about disease pressure built up in no-till fields? Solution, spray fungicides.
Burning off a green manure crop (the research has been done) is not as effective as the nutrient cycle don't take place very quickley as plants remain on the soil surface.
I think some of our biggest enemies against yield are one we are not even aware off, like compaction. We grow crops with mega amounts of chemical fertilizer that grow at shallow depths, and once they run out of rainfall (even though the yield potential is there through nutrient planning), fail to yield. The roots cannot break the hardpan, and if they do the plant has spent it's enery breaking the pan rather than making yield.
Crops like alfalpha and clover have deep tap roots the break these compaction zones. Once again like Parsley would say, rotation, rotation, rotation.
Any dummy can conventionally farm. Just look to your neighbour or phone your local agrologist. Takes one hell of a farmer to pull of organics, and it can be done. Organcis can yield with conventional crops. It has been proven. The trick is getting our land back into the the proper state.
Too much emphasis has been put on the negative effects of tillage. But it is only one small piece of the puzzle.
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wedino, is a pound of nitrate equal to a pound of nitrite and are those equal to a pound of ammonia or a pound of ammonium? How many pounds of nitrogen are represented by soil bacteria?
I listened to a speaker with a PhD in soil microbiology say that bacteria contain a substantial portion of nitrogen perhaps 5%. The nitrogen contained in soil bacteria is not subject to leaching or gassing off as might be the case with NH3, NH4 and ammonia and ammonium. So is a pound of nitrogen a pound of nitrogen. I think not.
The speaker went on to say that a healthy soil might have 2000 pounds of soil bacteria. If those bacteria are 5% nitrogen that would be equal to 100 pounds of nitrogen per acre. If other aspects of the soil biology were in a similar healthy abundance then normal bacterial activity would make this nitrogen plant available in the root zone when the plant most needed it. In fact the plant exudes through the roots as much as 50% of the sugars produced by the leaves providing food for the soil bacteria and adding to the health of the soil microbes. I find that simply amazing.
A green manure plow down provides a lot of sugar for soil bacteria. I am sure we have all heard numerous times that the reason sugar is bad for your teeth is because it promotes bacterial growth. So yes you can do a green cover crop and spray it down but you will deprive the soil bacteria of a copious amount of sugars as the plant tops dry down. Plowing the top growth into the soil may not add a huge amount of nitrogen directly but it does have a significant effect on total bacterial nitrogen storage. The plow down of the top growth also assists long term humus development. The humus and other soil organic matter ties directly into the nitrogen cycling due to the activity of the soil bacteria.
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Vader. What do you use for a plow-down?
If I was to do it, here is what I would do. I would plant Trapper field peas at 1 bushel per acre along with 1/2 a bushel of oats per acres. I would single shoot these together and then broadcast through me double-shoot hose (spraying in-front of my sweep) a half rate of sweet yellow clover. I would seed as early as i could get on the land and plow it down at first flower.
Get bio-mass with the oats plus allopathy, hopefully N from the clover but also allopathy and N fixation from the peas. What do you think?
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Idea I have looked at. Intercrop sweetclover with spring cereal in year 1 and then in year 2 mow down sweetclover before seed set. Jill Clapperton has said that the residue breaks down very quickly due to the large amounts of N. My plan would be to mow high enough to leave stalks for snow catching. I would preseed burn early August for any regrowth and then plant winter wheat. A select variety would hopefully be able to use the slower release nitrogen for added protein( which you get paid for)Not sure if the sweet clover residue would have effect on winter wheat.
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Interesting. Be careful with inter-cropping clover. During harvest it can put a strong smell on your wheat. Also, it can (if it catches strong) compete very aggressively with the wheat crop. In year 2 watch for excess moisture uptake. The clover will have a developed root system with a stong tap root. May want to burn off and mow down early.
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I have alfalfa and clover in right now but am planning on green peas with cereal intercrop for this year. I had not thought to cut back so far on the peas. I thought maybe 2 bushels per acre and a bushel of oats.
Certainly the biggest hazard is the moisture used by alfalfa and clover. Could backfire on certain soil types with marginal moisture.
To properly understand the whole process I really think you need to listen to the soil foodweb CD.
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wedino, I spoke to Martin Entz at the University of Manitoba about green manure cover crops. He tells me that producers are having success with rolling down their cover crops to "terminate" them. You have to wait until they have bloomed otherwise they will just shoot up new growth.
Go to google and type in "rolling rye".
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