Nitrogen is one of the most crucial elements for biological systems and is required in large
amounts by plants for efficient growth. Farmers use more than 100 million metric tons of N
fertilizer each year, which consists of ammonia, nitrates, and other nitrogen-containing
compounds. Increasing use of N fertilizers in agriculture is negatively affecting the
environment and soil through soil acidification, pollution of groundwaters by nitrates, and
nitrous oxide gas emissions.
The excessive use of N fertilizers leads to soil acidification (low pH levels) creating an
unfavorable environment for soil microbes. Further, conventional tillage practices disrupt the
soil environment for better aeration create increased oxygen levels in the soil that can inhibit
Therefore, science has led us to look at microbial inoculants. These have proven to be
successful but will only be beneficial if it they are targeting a significant limitation in the soil
where it is applied. In the case of biological N-fixation, if plant growth is limited when N is
applied, other factors are limiting plant growth and an N-fixing inoculant may not be beneficial.
Routine soil tests measuring available soil N can be used to indicate potential for biological N-
fixing products to provide benefit.
For a more detailed discussion, see our FULL article Fixing our perspective on N-fixing.