Nitrogen, a primary nutrient essential for all life forms, is witnessing an imbalance across the globe. Some regions have a surplus, while others experience a shortage of this crucial element. This nitrogen variation has been highlighted in a recently published report.
Factors Impacting Nitrogen Decline
The rapid increase of carbon dioxide (CO2) levels and other global changes have heightened the demand for nitrogen by plants and microbes. When exposed to elevated CO2 concentrations, plants grow rapidly, which dilutes nitrogen availability within them, thereby increasing their demand for it. Moreover, warming and disturbances such as wildfires contribute to nitrogen decline as well.
In some parts of the world where human activity does not lead to an excess of nitrogen in the soil, long-term records reveal a decrease in nitrogen availability. This decline can cause significant consequences for plant and animal growth. Activities like burning fossil fuels, applying nitrogen-based fertilizers, and others dramatically elevate the amount of biologically available nitrogen in ecosystems.
Consequences of Nitrogen Imbalance
Low nitrogen availability is associated with an ‘Insect Apocalypse’ – Earth is losing about 1-2% of its insects annually due to climate change, insecticides, herbicides, light pollution, invasive species, and changes in agriculture and land use. Lower nitrogen availability could also limit plants’ ability to absorb CO2 from the atmosphere.
Excessive nitrogen in streams, inland lakes, and coastal bodies of water could lead to eutrophication, causing harmful algal blooms, dead zones, and fish kills. In humans, high nitrogen levels in groundwater are linked to intestinal cancers, miscarriages, and infant fatalities.
Key Highlights About Nitrogen
Nitrogen is a part of numerous molecules vital for life, including proteins, nucleic acids (DNA and RNA), and some vitamins. It is also found in other important biological compounds like alkaloids and urea.
Although nitrogen constitutes 78% of our atmosphere, it is largely inaccessible in this Nitrogen gas (N2) form to most organisms. This scarcity often limits primary productivity in many ecosystems. The conversion of Nitrogen gas into ammonia (NH3) makes it available to primary producers such as plants.
Nitrogen transformation occurs primarily through three processes: nitrogen fixation (from nitrogen gas to ammonia), nitrification (from ammonia to nitrite and nitrate), and denitrification (from nitrate to nitrogen gases). Nitrogen-fixing microorganisms play a crucial role in these processes.
Nitrogen Addition to Soil
Various factors add nitrogen to the soil. The excretion of urea by animals, including humans, contributes to soil nitrogen levels. However, the burning of coal does not directly enrich the soil with nitrogen. When plants and animals die, the nitrogen compounds in their organic matter re-enter the soil where they are broken down by decomposers. This decomposition process produces ammonia, which undergoes nitrification, i.e., nitrifying bacteria in the soil convert ammonia into nitrite and then into nitrate.
