Nitrogen has been a big topic for 2019. Most farmers and agronomists have difficultly measuring soil nitrogen availability. A strong understanding of nitrogen analysis can improve your management decisions and potentially reduce your nitrogen input costs.
In order to strengthen our knowledge of nitrogen cycling, we must answer a few key questions. How can we measure nitrogen availability? And are soil tests accurate predictors of nitrogen availability? To answer these questions, we spent some time looking into the research behind nitrogen analysis and soil testing. We found some interesting conclusions.
Soil nitrogen can be divided into two pools- inorganic nitrogen and organic nitrogen. Industry-standard measurements of soil nitrogen measure the inorganic pool (nitrate and ammoniated nitrogen).
This pool changes very rapidly, within days, and reflects only the immediately available pool. The inorganic nitrogen pool is also extremely vulnerable to environmental conditions. For this reason, in biological or organic farming systems the measurements of the inorganic pool of nitrogen are not good predictors of nitrogen availability. Rather, we should look to the organic pool.
When most people think of organic nitrogen, they think organic matter. Organic matter, however, can be very slow to respond to management and not an accurate measurement of in-season nitrogen availability. However, there is new research showing that measurements of soil protein (amino acids) can provide a more reliable measure of organic nitrogen in the soil.
This analysis is rapid and inexpensive. And for those who use amino-acid based fertilizers, such as fish fertilizer, these tests could prove valuable when predicting future application rates.