Alex Avery raises excellent questions that deserve answers. First though I wish to say that I don't feel that my report of very high organic corn yields amounts to "yield assertions" and they are certainly not exaggerated. As I said, they are easily verified facts. The certified organic corn was harvested by a new John Deere combine with a state-of-the-art yield monitor. The harvest was witnessed by John Deere reps who were demonstrating this new machine as well as many conventional farmers who had heard about 200+ bushel corn at the coffee shop and came to see if it was true. Please don't take my word for it: call Lakeland Equipment Co. at 716-526-6325. Ask for Ed Presher who was one of the witnesses. He can verify this and help you contact the other company personnel who came with the combine. The grain was loaded onto trucks and weighed. You can easily check this information.

My point is simply this: Because there are organic farmers presently attaining very high yields, we can know with certainty that organic farming is able to produce very high yields, just as conventional farming can.

Alex, I agree with your estimation of presently available nitrogen. If we were to farm as conventional farmers do now and only substitute organic inputs for conventional ones, we certainly would not have enough nitrogen. But here is where we differ: that is not true organic farming. I would call that "input substitution" and will be the first to tell you that it won't work agronomically nor economically. It also doesn't satisfy the long term requirements of organic certification standards. Unfortunately that is exactly what some university studies comparing organic to conventional yields and profits that I have reviewed were doing. A true "systems comparison" is the only acurate way to evaluate organic vs conventional yields and profits. The Rodale Institute in Pennsylvania has done a long term systems comparison that comes as close as any I have seen to doing this. You may be interested in reading it. Jeff Moyer at the Rodale Institute could tell you more about this research. Partly because of herbicide residues, conventional farms make little use of cover crops. On a well managed organic farm, soil is kept covered with legume cover crops in the fall, winter and early spring before land is prepared for planting. Often, these crops are interseeded into the crop so that as the crop matures and is harvested, the cover crop is already established.This provides a large supply of extra nitrogen that your studies don't take into account. It also prevents erosion and and saves nutrients that would otherwise leach. We generally 'frost seed' clover into our winter grains. After wheat harvest, a good stand of clover will provide about 350kg/ha of nitrogen before the land is plowed late in the following spring. This can easily produce 14000 kg/ha of corn. Prof. Trewavas' calculations on nitrogen to protein conversion in his recent post are incorrect. Protein is 16% nitrogen on the average so that there is about 1 pound of nitrogen in 6.25 pounds of protein. This illustrates the great importance of accuracy. Mistakes like this can lead to wrong conclusions. I must say that my direct knowledge of organic farming is limited to the northern United States and I can't comment on practices used in other areas in the studies that you cited. Thank you for your excellent questions, Alex. Prof. Trewavas also raised good points that I will address. "There is no known method of conjuring nitrogen out of nowhere." You are right! That statement also explains why your assumption that alfalfa can only fix 200kg/ha can't be correct. Alfalfa in state yield trials in the northern United States commonly averages about 17000kg/ha with top varieties above 22000kg/ha. Alfalfa is not fertilized with nitrogen. Assuming an 18.75% average protein content, which alfalfa often surpasses, the crop contains about 3% nitrogen. ( I explained your error in protein to nitrogen converson earlier ) The average annual removal of nitrogen is 510kg/ha not counting that contained in roots or absorbed into the soil. It can be more than 660kg/ha from the top varieties. Your earlier post underestimated clover and soybean nitrogen fixation by even wider margins.

I'm sorry if I gave the impression that the fields I mentioned earlier were only cropped every other year. They are intensively farmed every year with a rotation that allows cover crops to supply large amounts of nitrogen just ahead of crops with high nitrogen requirements. Beans or light nitrogen feeding crops are planted at points in the rotation when nitrogen supply is lower. A common rotation would be Year 1: wheat underseeded with clover, Year 2: corn, Year 3: soybeans, Year 4: spelt (interseeded at soybeans' yellow leaf stage or sown immediately after soybean harvest in year 3) underseeded with clover, Year 5: vegetables such as sweet corn which are harvested early enough for a cover crop to be grown. In each year when cover crops are grown, please notice that they have much time to grow after the main crop is harvested (wheat and spelt are harvested in July, sweet corn is harvested in July-August) before they are plowed in May of the following spring. This results in 2 very heavy growths of clover, one between July-December and one between March-May. Additionally, the soil is protected from erosion during this vulnerable time. In a sense, this is double cropping the land. There is no need to take land out of production for a year to accumulate nitrogen with this type of rotation. Please also note that we use no animal manure to acheive adequate nitrogen levels. Animal manure use is certainly not as ubiquitous or as necessary on organic farms, as people seem to think.

The high corn yield I spoke of was not a one time event on only one field. Similar yields were harvested from other fields and in other crop years. For example on a different field, 13100kg/ha of corn was harvested in 1998 followed by 3400kg/ha of dark red kidney beans in 1999. That was more than twice average yield of conventional kidney beans in drought-stressed 1999 for this area. The field is now nearing harvest of a good crop of spelt and the clover cover crop is already 20 cm high. Again, don't just take my word for it. You may call Skip Stickler at the Agway Bean Company in Geneva, NY, 315-781-1990, for confirmation of these facts. I guess I feel there is nothing 'old fashioned' about corn or bean yields like this - we have not 'gone back to organic farming' nor have we returned to the low yields and management style of the pre-chemical era. Indeed, I feel that this type of farming requires a very high level of management and an extensive understanding of science.

This information is not 'claims', these are observations that easily verified. Please don't tell me that they are not possible, instead, just follow this information up if you are still in doubt, rather than disputing it. When direct observations like these contradict assumptions, perhaps it is time to reconsider the assumptions.

I am quite familiar with both European and American organic standards. There are Materials Lists of approved fertility amendments in both the USDA proposed National Organic Program Standards and the EU 2091/92 regulation. They both prohibit artificial fertilizers but they allow the use of natural mined minerals, such as potassium sulfate or zinc sulfate. Organic farming does NOT mean no fertilizer. Many certifiers require soil testing and the use of corrective mineral amendments where they are needed and at appropriate rates to correct deficiencies when justified. The organic farmers that I work with are very aware of their soil fertility status and use organic fertilizers accordingly. Most try to apply corrective fertility amendments to the cover crops. This is particularly important when using materials such as rock phosphate which breaks down slowly.

Mr. Nicholl also raised a very good point about organic prices. I certainly do not understand why organic foods command such a premium price in the market other than supply and demand, and that the market is bearing the high prices. However, the premium seen in the store is not terribly reflective of what the farmer is receiving. For example, the organic premium to the farmer on processing sweet corn is 2.5 cents/lb. This becomes less than 4 cents/lb over conventional in the finished product after adjusting for the proccessing loss. To organic farmers, this 2.5 cents is quite lucrative. We've noticed that organic vegetables tend to be about double the price of conventional vegetables in the store. While we certainly recognize there are costs involved in processing and distribution, the processing/distribution costs for organic product can't be double what they are for conventional products. I would guess that this pattern holds true for other organic crops. Someone is indeed making a lot of money on these products.

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