One of the great mysteries of the past 1000 years of soil studies has apparently been answered. The great nitrogen mystery is how nitrogen gets into the soil. Plants need nitrogen, and they need it in the form of nitrates and other compounds essential to plant growth.
Most of us put fertilizer on our plants to make them healthy and don’t think about the fact that while our atmosphere is 78% nitrogen, plants can’t absorb the nitrogen directly from the air. In high school, we learned about “nitrogen fixation” and were told about nitrogen-fixing bacteria and the role of lightning in transforming atmospheric nitrogen into forms that could be used by plants.
Plant scientists have known that this model was not complete. The nitrogen cycle clearly had some missing parts, and our knowledge of how nitrogen gets into the soil was obviously lacking. Scientists have now discovered that a significant portion of getting nitrogen to plants involves seeping through bedrock. Nitrogen becomes trapped in sedimentary rocks in the oceans. When tectonic activity lifts the sedimentary rocks, so they are at the surface of the Earth, they begin to release their nitrogen to the soils above them, Studies in California show that soils above sedimentary rocks contain 50% more nitrogen than soils above volcanic rocks.
This discovery is a breakthrough in soil chemistry and has strong implications for how we can accelerate plant growth. Choosing places suitable for agriculture can be made more accurate with this new understanding. The complexity of Earth’s various cycles to allow for plant growth and to provide for human needs is astounding. Even such a fundamental question as the nitrogen mystery is still revealing God’s wisdom and planning in providing a life-supporting planet for us to live.
–John N. Clayton © 2018
Reference: Scientific American, July 2018, page 15-17.