The nitrogen cycle describes the uses and re-uses of one of the four most plentiful elements in the human body. Nitrogen is the vital component of DNA and RNA. Nitrogen is found in every one of the twenty amino acids our body cells synthesize in multiple ways to form tens of thousands of proteins--the building blocks of our physical bodies. In brief, plants need nitrogen for healthy growth. Directly or indirectly, animals eat plants because they need nitrogen to sustain virtually every function of the body.
What nitrogen is doing in our world and how plants acquire their needed nitrogen is of immense importance. The atmosphere is composed of 78% nitrogen. Unlike oxygen, nitrogen is very unreactive. In its gas state, it is useless to plants. Nitrogen, therefore, must be chemically combined into compounds with other elements so it may be absorbed into plant bodies. In such compounds, such as nitrates, the nitrogen becomes useful to the plant. Several natural processes do the task very well. In one of them, nitrogen fixation, atmospheric nitrogen is synthesized by bacteria into compounds such as ammonia which supplies nitrogen in a form plants are able to use.
Nitrogen-fixing bacteria supply needed nitrogen to plants and in return receive nutrients from the plant. This mutually beneficial relationship is called symbiosis. Plants known as legumes, such as peas, beans, peanuts, and many others have this ability within their root nodules. Some bacteria are able to reverse the process and return free nitrogen to the atmosphere in a process called denitrification. We are describing the nitrogen cycle, the endless use and re-use of one of earth’s elements or resources over time. The nitrogen cycle is only one of an abundance of wonderful natural cycles sustaining our existence. Cycles are a small part of many intricate design features on our planet.
The last century has seen astonishing progress in understanding nature’s cycles and processes and developing manmade strategies to use them effectively for man’s benefit. For example, in the early 20th century, a method called the Haber process was developed. Natural gas (methane) was processed to produce hydrogen gas, later to be combined with atmospheric nitrogen to form ammonia gas. This ammonia gas, in turn, is treated to form ammonium nitrate, a popular nitrogen fertilizer. While the chemical reactions in this process are simple, the industrial application of the simple chemistry is complex and somewhat dangerous. Nevertheless, production of fertilizers such as ammonium nitrate exceeds 500 million tons per year. Roughly one-half of the world’s population is nutritionally sustained by synthetic nitrogen fertilizers. On an enormous scale, scientists now apply the knowledge of plant nutrition known to man for centuries.
These man-made applications have not occurred without environmental impact. Nitrogen and other chemical residues leech into water supplies with some adverse effects. Beneficial technology has also produced some solutions to the problems. World population has more than tripled in the last century, owing to progress in human knowledge on many fronts.
As I recall the large piles of bagged fertilizer ordered by my father with “ammonium nitrate” printed on the bags, the awareness washes over me that my father was ahead of his time. He knew the benefits of hybrid seeds and application of modern plant nutrition practices. He also knew the benefits of planting annual cover crops and periodic lime applications on his twelve acres of sweet corn in order to be able to raise the same crop on the same land year after year without any reduction in yield. He took advantage of the benefits of crop rotation without actually rotating the crops. In this way he followed the mandate of Genesis 1:28 to “…multiply and fill the earth and subdue it” without imposing any harm on the land. Our family likes to think of his application of knowledge and wisdom as God-given.
Psalm 104: 24 (NLT) exults “O Lord, what a variety of things you have made! In wisdom you have made them all…” We need to remind ourselves that our extensive local supermarket array of attractive food products is but a miniscule fraction of the nutritional needs of seven billion people.