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Human impact on the nitrogen cycle is diverse. Agricultural and industrial nitrogen (N) inputs to the environment currently exceed inputs from natural N fixation . [ 1 ] As a consequence of anthropogenic inputs, the global nitrogen cycle (Fig. 1) has been significantly altered over the past century.
The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmospheric, terrestrial, and marine ecosystems. The conversion of nitrogen can be carried out through both biological and physical processes.
The nitrogen cycle is of particular interest to ecologists because nitrogen availability can affect the rate of key ecosystem processes, including primary production and decomposition. Human activities such as fossil fuel combustion, use of artificial nitrogen fertilizers, and release of nitrogen in wastewater have dramatically altered the ...
Nitrogen's effects on agriculture profoundly influence crop growth, soil fertility, and overall agricultural productivity, while also exerting significant impacts on the environment. Nitrogen is an element vital to many environmental processes. Nitrogen plays a vital role in the nitrogen cycle, a complex biogeochemical process that involves the ...
A biogeochemical cycle, or more generally a cycle of matter, [1] is the movement and transformation of chemical elements and compounds between living organisms, the atmosphere, and the Earth's crust. Major biogeochemical cycles include the carbon cycle, the nitrogen cycle and the water cycle. In each cycle, the chemical element or molecule is ...
Other significant processes in the nitrogen cycle are nitrification and ammonification which convert ammonium to nitrate or nitrite and organic matter to ammonia respectively. Because these processes keep nitrogen concentrations relatively stable in most ecosystems, a large influx of nitrogen from agricultural runoff can cause serious ...
Lichens are symbiotic organisms that play an important role in the biogeochemical cycle on Earth. The characteristics of lichens, such as strong resistance to factors such as desiccation, ability to grow and break down rocks allow lichen to grow in different types of environment including highly nitrogen limited area such as subarctic heath.
There is much overlap between the terms for the biogeochemical cycle and nutrient cycle. Most textbooks integrate the two and seem to treat them as synonymous terms. [5] However, the terms often appear independently. The nutrient cycle is more often used in direct reference to the idea of an intra-system cycle, where an ecosystem functions as a ...