Has Nitrogen been depleting our soils?
Use of synthetic nitrogen may be the number one cause of declining soil fertility and soil organic matter. At first this seems to contradict our understanding of how important nitrogen is for crops. After all, nitrogen boosts plant growth, which produces bigger crops and also more crop residue that can build soil organic matter. But that’s not the effect that’s actually happened. Soil organic matter has declined everywhere we’ve farmed with modern methods. It appears that synthetic nitrogen is the primary cause.
This has been known by organic ag leaders since Sir Albert Howard explained the connection in 1947, but has otherwise been rarely taught or discussed.
An article posted at our website reports on the work of University of Illinois researchers, explaining how this happens and the scientific studies in Illinois and Iowa that document the effect. Use of excess nitrogen actually causes depletion of soil organic matter. That in turn has reduced the water-holding capacity and the nutrient holding capacity of soils.
This is not new information. The long-term studies were reported between 2006 to 2009. Since it’s still not penetrated our farming paradigm, let’s review the science and the conventional wisdom.
This reminds me of the difficulty I have answering the question: if Pacific Gro delivers just 2.2 lbs of N in 10 gallons, where does the rest of my crop’s nitrogen come from? Well … for starters, the air we breathe is 78% nitrogen. Plentiful soil biology can deliver nitrogen and other nutrients to crops if we take care of the soil habitat.