Nitrogen and Non-Protein Nitrogen's effects on Agriculture
Nitrogen's effects on agriculture profoundly influence crop growth, soil fertility, and overall agricultural productivity, while also exerting significant impacts on the environment.
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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 transformation of nitrogen between different chemical forms and its movement through various environmental compartments such as the atmosphere, soil, water, and living organisms.[1] In its natural state, nitrogen exists primarily as a gas (N2) in the atmosphere, making up about 78% of the air we breathe. Nitrogen finds extensive usage across various sectors, primarily in the agriculture industry, and transportation. Its versatility stems from its ability to form numerous compounds, each with unique properties and applications.
Impacts on agriculture
editNitrogen is a fundamental nutrient in agriculture, playing a crucial role in plant growth and development. It is an essential component of proteins, enzymes, chlorophyll, and nucleic acids, all of which are essential for various metabolic processes within plants.[2] When discussing the application of nitrogen in agriculture, it is essential to consider the sources of nitrogen used. Synthetic nitrogen fertilizers, such as ammonium nitrate and urea, are commonly applied to crops to replenish soil nitrogen levels and enhance crop productivity[3] These fertilizers provide readily available nitrogen for plant uptake, thereby promoting vigorous vegetative growth and improving yields. However, the excessive or inefficient use of nitrogen fertilizers can lead to environmental problems such as nitrogen leaching, runoff, and emissions of nitrogen oxides (NOx).[4] Nitrogen leaching occurs when nitrogen compounds, primarily nitrates, move through the soil profile and enter groundwater, potentially contaminating drinking water sources.[2] To mitigate these environmental impacts, various nitrogen management strategies are employed in agriculture. Soil testing is an essential practice that helps farmers assess the nutrient status of their soils and determine appropriate fertilizer application rates. Nutrient management plans based on soil test results help optimize fertilizer use efficiency while minimizing nitrogen losses to the environment.
Effects on water quality
editWater quality is greatly influenced by nitrogen, which also has an impact on ecosystems in settings that have been modified by humans. Even though nitrogen is a necessary element for life, too much of it in water can have negative effects on aquatic ecosystems and endanger human health. Agricultural runoff, where fertilizers containing nitrogen compounds can seep into rivers, lakes, and groundwater, is one of the main sources of nitrogen in water. Urban areas also release wastewater and add nitrogen through stormwater runoff. The process of eutrophication, in which an abundance of nutrients encourages the growth of algae and other aquatic plants, can be brought on by elevated nitrogen levels in water.[5]
Non-protein nitrogen
editNon-protein nitrogen (or NPN) is a term used in animal nutrition to refer collectively to components such as urea, biuret, and ammonia, which are not proteins but can be converted into proteins by microbes in the ruminant stomach. Due to their lower cost compared to plant and animal proteins, their inclusion in a diet can result in economic gain, but at too high levels cause a depression in growth and possible ammonia toxicity, as microbes convert NPN to ammonia first before using that to make protein.[6] NPN can also be used to artificially raise crude protein values, which are measured based on nitrogen content, as protein is about 16% nitrogen and the only major component of most food that contains nitrogen is protein. The source of NPN is typically a chemical feed additive, or sometimes chicken waste,[7][8] and cattle manure.[9][10] However, excessive intake of NPN can have adverse effects on animal health and productivity, as well as environmental implications.
Agricultural effects
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In ruminant nutrition, NPN sources such as urea are commonly used as supplements to provide additional nitrogen for microbial protein synthesis in the rumen. Microbes in the rumen can utilize NPN to synthesize microbial protein, which is subsequently digested and absorbed by the animal. This microbial protein serves as a source of amino acids for the animal, supporting growth and productivity,[11] However, excessive consumption of NPN can lead to toxicity issues in ruminants. High levels of ammonia resulting from the breakdown of NPN can disrupt rumen pH balance and microbial activity, leading to conditions such as rumen acidosis and ammonia toxicity.[12] Furthermore, excessive excretion of nitrogen in urine and feces from animals consuming diets high in NPN can contribute to nitrogen pollution in the environment. Nitrogen runoff from agricultural operations can lead to eutrophication of water bodies, harmful algal blooms, and degradation of aquatic ecosystems[13]
See also
editReferences
edit- ^ Galloway JN, Dentener FJ, Capone DG, Boyer EW, Howarth RW, Seitzinger SP, et al. (2004-09-01). "Nitrogen Cycles: Past, Present, and Future". Biogeochemistry. 70 (2): 153–226. Bibcode:2004Biogc..70..153G. doi:10.1007/s10533-004-0370-0. ISSN 1573-515X.
- ^ a b Good AG, Shrawat AK, Muench DG (December 2004). "Can less yield more? Is reducing nutrient input into the environment compatible with maintaining crop production?". Trends in Plant Science. 9 (12): 597–605. doi:10.1016/j.tplants.2004.10.008. PMID 15564127.
- ^ Ju XT, Xing GX, Chen XP, Zhang SL, Zhang LJ, Liu XJ, et al. (March 2009). "Reducing environmental risk by improving N management in intensive Chinese agricultural systems". Proceedings of the National Academy of Sciences of the United States of America. 106 (9): 3041–6. doi:10.1073/pnas.0813417106. PMC 2644255. PMID 19223587.
- ^ Davidson EA, Belk E, Boone RD (February 1998). "Soil water content and temperature as independent or confounded factors controlling soil respiration in a temperate mixed hardwood forest". Global Change Biology. 4 (2): 217–227. Bibcode:1998GCBio...4..217D. doi:10.1046/j.1365-2486.1998.00128.x. ISSN 1354-1013.
- ^ "Nitrogen and Water". U.S. Geological Survey. Retrieved 2024-03-11.
- ^ Steiner Z, Klarić I, Novoselec J, Klir Ž, Antunović B, Babić I, et al. (2019). "Research on influence of different non-protein nitrogen (NPN) compounds in beef cattle feeding". Journal of Central European Agriculture. 20 (1): 31–35. doi:10.5513/JCEA01/20.1.2378. ISSN 1332-9049.
- ^ Oltjen RR, Dinius DA (July 1976). "Processed poultry waste compared with uric acid, sodium urate, urea and biuret as nitrogen supplements for beef cattle fed forage diets". Journal of Animal Science. 43 (1): 201–208. doi:10.2527/jas1976.431201x.
- ^ Gihad EA (March 1976). "Value of dried poultry manure and urea as protein supplements for sheep consuming low quality tropical hay". Journal of Animal Science. 42 (3): 706–709. doi:10.2527/jas1976.423706x.
- ^ Smith LW, Wheeler WE (January 1979). "Nutritional and economic value of animal excreta". Journal of Animal Science. 48 (1): 144–156. doi:10.2527/jas1979.481144x.
- ^ Fontenot JP, Smith LW, Sutton AL (July 1983). "Alternative utilization of animal wastes". Journal of Animal Science. 57 (suppl_2): 221–233.
- ^ Broderick GA (April 2003). "Effects of varying dietary protein and energy levels on the production of lactating dairy cows". Journal of Dairy Science. 86 (4): 1370–1381. doi:10.3168/jds.S0022-0302(03)73721-7. PMID 12741562.
- ^ Van Soest PJ (2019-12-31). Nutritional Ecology of the Ruminant. Ithaca, NY: Cornell University Press. doi:10.7591/9781501732355-003. ISBN 978-1-5017-3235-5.
- ^ Glibert PM, Harrison J, Heil C, Seitzinger S (February 2006). "Escalating Worldwide use of Urea – A Global Change Contributing to Coastal Eutrophication". Biogeochemistry. 77 (3): 441–463. Bibcode:2006Biogc..77..441G. doi:10.1007/s10533-005-3070-5. ISSN 0168-2563.
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