Re: [compost_tea] nutrients, was Kelp Questions

From: <soilfoodweb_at_aol.com>
Date: Fri, 09 May 2003 10:22:26 -0400

The question of adding too much nitrogen.....

You need to know what form your nitrogen is in. I know that some of the chemies say "Nitrogen is nitrogen", but no, nitrate can be much more harmful than protein, especially in the category of "too much".

Nitrate helps the disease-causing fungi to outcompete the beneficial fungi. If oxygen is limiting at the same time, then the disease organisms have the total upper hand. It is hard not to have disease in those conditions.

Convert your nitrate (NO3) to bacterial and fungal biomass, and the disease problem will be remediated. Remove the lack of oxygen, and bingo, the beneficial fungi have a chance to gain the upper hand, and the plants improve.

Adding nitrogen as bactreial and fungal biomass is probably never going to be a real problem. Could you over-do additions? If the organisms are asleep, I don't believe it could ever be a problem. Note the work belief. There probably is some extreme situation where addition of really high microbial biomass would be detrimental - just as too much water will drown you. But, within reason, adding extreme amount of N as dormant biomass won't ever cause a problem.

Addition of even 10 ppm nitrate harms some of the beneficial microbes in the soil. Same thing with nitrite (I'm not so certain about the concentration of nitrite that would cause damage, but that information probably exists in the scientific literature). Clearly, too high ammonia and you have leaf burning, root pruning, and other symptoms of malaise in your plants. Ammonium is so rapidly converted to nitrite and nitrate in alkaline soils that addition of high levels of ammonium rapidly become a nitrate problem. In slightly acid soils, ammonium helps out Fusarium, Pythium, etc.

Addition of protein in the form of amino acids, fatty acids, carbohydrates can be problems, becasue these are food resources for bacteria and fungi, and high growth rates of bacteria and fungi can suck up all your nitrogen, and all your oxygen, leaving the plants "up a crick".

Lack of oxygen is not the problem for plants, plants take up CO2 and release O2 as a waste product. Lack of oxygen results in growth of anaeorbic bacteria, and the products of anaerobic metabolism kill roots.

Addition of N as dormant bacteria, or fungi, will not cause bacterial ro fungal growth to go crazy, however. Addition of N as recalcitrant compounds, like fish oils, woody materials (but balanced woody materials which means composted woody material), is the way to safely add N to the soil.

OK? The form of N is really important.

Elaine Ingham
President, Soil Foodweb Inc.
SFI Corvallis, OR
SFI Port Jefferson, NY
SFI Lismore, NSW, Australia
SFI Hilversum, The Netherlands
SFI Cambridge, New Zealand
www.soilfoodweb.com

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Received on Fri May 09 2003 - 12:23:15 EDT

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