How does agriculture affect nitrogen cycle


Agricultural production is dependent, in part, on the cycling of nitrogen within the rural environment. Figure 1 illustrates the various forms and pathways that nitrogen (N) can take as it cycles through an agricultural production system. Before nitrogen can be used by plants, it must be converted into forms that are available to plants; this conversion is called mineralization.

The emissions of N2O from agricultural practices act to warm the climate and to impact the stratospheric ozone layer. Nitrogen deposition stemming from manure and synthetic fertilizer application exerts a substantial lever on the atmospheric carbon cycle through its impact on plant growth.


What is the formula for the nitrogen cycle?

nitrogen gas, ammonia, ammonium ion, nitrite ion, nitrate ion, sulfur, phosphorus, water and enzymes of various types What is the formula for nitrogen gas? N2 What is the formula for the nitrite ion? NO2 – What is the formula for ammonia? NH3 What is the formula for the ammonium ion? NH4+ What is the formula for the nitrate ion? NO3-

How do you explain the nitrogen cycle?

The stages of the nitrogen cycle

  1. Nitrogen-fixation. Legume plants such as peas, beans and clover contain nitrogen-fixing bacteria. …
  2. Feeding. Animals consume plant protein, digest it using specific enzymes and absorb the free amino acids.
  3. Production of nitrogenous waste products. …
  4. Decomposition. …
  5. Nitrification. …
  6. Uptake of nitrates. …
  7. Denitrification. …

What is nitrogen cycle explain with diagram?

What is nitrogen cycle with diagram? Nitrogen Cycle is a biogeochemical process through which nitrogen is converted into many forms, consecutively passing from the atmosphere to the soil to organism and back into the atmosphere. It involves several processes such as nitrogen fixation, nitrification, denitrification, decay and putrefaction.

What is the role of nitrogen in agriculture?

nutrients, nitrogen is the first and foremost nutrient required for crop plants as it is the constituent of chlorophyll and many proteins and enzymes and thus plays a significant role during the vegetative growth of crops. Nitrogen is absorbed by the plants in the form of nitrate (NO− 3) and ammonium (NH+ 4

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How is the nitrogen cycle related to agriculture?

It plays a key role in plant growth: too little nitrogen and plants cannot thrive, leading to low crop yields; but too much nitrogen can be toxic to plants [1]. Nitrogen is necessary for our food supply, but excess nitrogen can harm the environment.

How is agriculture responsible for disruption of nitrogen cycle?

In agricultural systems, fertilizers are used extensively to increase plant production, but unused nitrogen, usually in the form of nitrate, can leach out of the soil, enter streams and rivers, and ultimately make its way into our drinking water.

How does agriculture influence the nutrient cycle?

Furthermore, agriculture also influences the nutrient cycle in another way: agriculture accelerates land erosion — because ploughing and tilling disturb and expose the soil — so more nutrients drains away with runoff (see also soil degradation). And flood control contributes to disrupting the natural nutrient cycle.

How can fertilizers affect the nitrogen cycle?

Nitrogen from fertilizers sinks into soils, often creating conditions that favor the growth of weeds rather than native plants. Nitrogen then washes into waterways, causing a surplus of nutrients, a situation called eutrophication.

How does harvesting crops affect the nitrogen cycle?

Nitrogen can be lost from the cycle. It can be lost to the atmosphere, removed by harvesting crops or lost to surface water or groundwater. However it is lost, nitrogen can enter the cycle again through one of the processes discussed above or through other processes.

What is nitrogen in agriculture?

Nitrogen is an essential nutrient for the production of amino acids, proteins, nucleic acids, etc., and stone fruit trees require an adequate annual supply for proper growth and productivity. Nitrogen is primarily absorbed through fine roots as either ammonium or nitrate.

What factors affect the nitrogen cycle?

Inherent factors such as rainfall and temperature; and site conditions such as moisture, soil aeration (oxygen levels), and salt content (electrical conductivity/EC) affect rate of N mineralization from organic matter decomposition, nitrogen cycling, and nitrogen losses through leaching, runoff, or denitrification.

How is agricultural nitrogen made?

The Haber-Bosch process utilizes hydrogen and atmospheric nitrogen under extremely high pressure and temperature in combination with a metal catalyst such as iron to produce ammonia gas, which is condensed with the help of cold water, forming liquid ammonia also known as anhydrous ammonia (Figure 1A).

How are humans affecting the nitrogen cycle?

Humans are overloading ecosystems with nitrogen through the burning of fossil fuels and an increase in nitrogen-producing industrial and agricultural activities, according to a new study. While nitrogen is an element that is essential to life, it is an environmental scourge at high levels.

Why is Nitrogen Cycle Important?

The critical balance of substances that is important for maintaining life is an essential area of research. The balance of nitrogen content in the environment is no different. When plants lack nitrogen, they become yellow and have stunted growth, and they produce smaller flowers and fruits.

Nitrogen Cycle is Key To Life

Nitrogen is a critical element of the nucleic acids DNA and RNA. Deoxyribonucleic acid or DNA is a self-replicating compound present in all living beings. It is the main component of chromosomes and carrier of genetic information. Ribonucleic acid or RNA is present in all living cells and it acts as a messenger carrying instructions from DNA.

What is Eutrophication ?

Excess amount of nitrogen can drain from the soil into underground water sources or enter aquatic systems as above-ground runoff. This excess amount of nitrogen can build up and lead to eutrophication. Eutrophication occurs when large amount of nitrogen enriches the water, leading to excessive growth of plants and algae.

How to Prevent Eutrophication?

People managing water resources use different methods to reduce the harmful effects of algal blooms and eutrophication of water bodies. One of the methods is to re-reroute excess nutrients away from vulnerable costal zones and lakes. They can also use herbicides or algaecides to prevent the algal blooms, and reduce the quantities.

What Exactly is the Nitrogen Cycle?

Nitrogen moves from atmosphere to the earth, through soils, and back to the atmosphere in a cyclic manner. This cyclic processes is known as the nitrogen cycle. Nitrogen must change forms to move through the different parts of the cycle. In atmosphere, nitrogen exists as a gas, but in the soil, it exists as nitrogen oxide, and nitrogen dioxide.

Stage 1: Nitrogen Fixation

In the first stage, nitrogen moves from the atmosphere into the soil. Earth’s atmosphere contains a huge amount of nitrogen gas. However, this nitrogen in gaseous form cannot be used directly by plants. Nitrogen needs transformation through the nitrogen fixation process.

Stage 2: Mineralization

This stage of mineralization takes place in the soil. Nitrogen moves from organic materials to an inorganic form of nitrogen which can be used by the plants. Eventually, the nutrients of plants gets used up completely. Finally, the plant dies and decomposes. Mineralization occurs when microbes act on organic material.

How does N2O affect the climate?

The emissions of N2O from agricultural practices act to warm the climate and to impact the stratospheric ozone layer. Nitrogen deposition stemming from manure and synthetic fertilizer application exerts a substantial lever on the atmospheric carbon cycle through its impact on plant growth.

What is the largest fraction of nitrogen emissions?

Presently, agricultural reactive nitrogen emissions, primarily of ammonia, make up the largest fraction of emitted reactive nitrogen emissions to the atmosphere. As reactive nitrogen cascades through the environment it impacts air quality and climate.

How do farmers use nitrogen?

Farmer’s need to grow a large amount of plants in a small area. Each one of these plants needs nitrogen to produce chlorophyll and grow to provide food. Plants can only absorb nitrogen in the forms of nitrate and ammonium. Farmers often find that their is not enough nitrate and ammonium in the soil to support such drastic growth, so they manipulate the nitrogen cycle by giving their plants nitrogen based fertilizers. Nitrogen fertilizers are made using the Haber Bosch Process which combines nitrogen from the air with hydrogen to produce ammonia. Doing this on a large scale can affect the balance of the nitrogen cycle and how much nitrogen gases (some of which are important greenhouse gases) are in the atmosphere.

What are the two areas of Connecticut that are most susceptible to eutrophication?

Two parts of Connecticut are especially susceptible to eutrophication; Long Island Sound and Candlewood Lake. When high amounts of nitrogen enter these waters, algae and phytoplankton grow at rapid rates. An abundance of algae causes, a depletion of oxygen in the water, this creates a dead zone. Long Island Sound has three instances a year where hypoxia, or low oxygen levels, occur. These episodes usually occur during the summer, and the conditions have worsening every year. Hypoxia causes fish to scatter and become very susceptible to disease, and in extreme cases, when oxygen levels become extremely low, fish and other shellfish may die. Excessive amounts of nitrogen can contaminate the water and the shellfish. This can cause people who come in contact with the tainted shellfish to become ill. This can happen in both Candlewood Lake and Long Island Sound, and even other bodies of water in Connecticut.

Why do dead zones occur in water?

When farmers use soils high in nitrogen, the excess amount ends up leaking into the water through runoff. When too much nitrogen enters the water, immense amounts of algae begin to grow, which is the cause of dead zones. Because organisms need oxygen to live, the dead zones, which are low in oxygen, cause them to die off. Therefore, if this problem is not addressed, and farmers do not cut down on their usage of (??)soils containing nitrogen, more dead zones will appear and cause death to many organisms.

What is the process of nitrification inhibition?

Scientists are investigating the merits of biological nitrification inhibition, a process through which a plant excretes material which influences the nitrogen cycle in the soil. Where this process occurs naturally — in some grasses and wheat wild relatives — it helps to significantly reduce nitrogen emissions.

What is the most important nutrient in crop production?

Nitrogen is the most essential nutrient in crop production but also one of the most challenging to work with. The compound is central to global crop production — particularly for major cereals — but while many parts of the world do not have enough to achieve food and nutrition security, in others excess nitrogen from fertilizer leaks into …

What is the process of nitrogen fixation?

Atmospheric nitrogen must go through a natural process called nitrogen fixation to transform before it can be used for plant nutrition.

How much nitrogen is needed to meet global food demand?

Currently, average global nitrogen use efficiency does not exceed 50%, which falls short of the estimated 67% needed to meet global food demand in 2050 while keeping surplus nitrogen within the limits for maintaining acceptable air and water qualities.

What gas dissolves in rain?

The process can also begin with lightning, the heat from which ruptures the triple bonds of atmospheric nitrogen, freeing its atoms to combine with oxygen and create nitrous oxide gas, which dissolves in rain as nitric acid and is absorbed by the soil.

Which country is the largest producer of nitrogen?

Eventually China, the world’s most populous country, became, and remains, the largest user as well as the largest producer of synthetic nitrogen (FAO 2011).

How much nitrogen is in recycled straws?

Traditional recycling of organic wastes could supply only a limited amount: the nitrogen content of these wastes is inherently low, typically less than 0.5% in cereal straws, 2-4% in animal manures, and nitrogen losses before and after their application are high.

What is the most complex cycle of all circulating elements?

Nitrogen cycle and world food production. In the biosphere nitrogen has the most complex cycle of all circulating elements. Its incessant reuse makes life on Earth possible. Traditional agricultures supplied limited amounts of the nutrient by recycling organic wastes and by planting leguminous crops.

How many people in the world are without nitrogen fertilisers?

Without the use of nitrogen fertilisers we could not secure enough food for the prevailing diets of nearly 45% of the world’s population, or roughly three billion people. These diets are excessive in rich countries, adequate in China, but inadequate in much of Africa.

Which countries were the first to use nitrogen fertiliser?

European, North American and Japanese agricultures were the first beneficiaries of inexpensive nitrogenous fertilisers. By the 1960s rising nitrogen application made it possible to realise high yields of new short-stalked wheat and rice cultivars planted in low-income countries of Asia and Latin. America.

When was ammonia first used in agriculture?

Only the Haber-Bosch synthesis of ammonia, first commercialised in 1913, removed this key constraint on crop productivity. Global agriculture has become steadily more dependent on synthetic nitrogenous compounds without whose applications we would not be able to produce roughly half of today’s world food.

Who was the first person to use nitrogen fertiliser?

John Bennet Lawes (1814- 1900) and Joseph Henry Gilbert (1817-1901) initiated the first continuous experiments with crops receiving different amounts of fertilisers and demonstrated, beyond any doubt, that nitrogen fertilisers (followed by phosphates) are the key to higher grain crop yields.

How does nitrogen affect agriculture?

Farm Management Options. When nitrogen leaves the root zone , it can affect the quality of groundwater and surface water. The key to reducing this is practising efficient on-farm management of nitrogen, so that as much of the available nitrogen as possible is used to grow crops and livestock and maintain soil health.

How to reduce nitrogen load?

Reduce total nitrogen loading 1 Ensure livestock feed rations are not any higher than necessary to meet production targets. This will save both feed costs and excess nitrogen loss in the manure. 2 Use nitrogen from sources available on the farm first, where possible (e.g., manure), before buying any nitrogen sources produced off-farm.

How to avoid ammonium losses?

Avoid applying manure near surface water or on steeply sloping land .

What is nitrite produced from?

Nitrite. Nitrite (NO 2-) is produced naturally as part of the process of converting ammonium into nitrate. It seldom accumulates in the soil, since the conversion from nitrite to nitrate is generally much faster than the conversion from ammonium to nitrite. Nitrite moves much like nitrate in the soil and groundwater zones.

How does nitrogen loss occur?

Natural losses of nitrogen, in addition to nitrate leaching, occur through ammonia volatilization and denitrification. Ammonia volatilization occurs when manure or an ammonia-based fertilizer (particularly urea) are applied to the surface of the soil without mixing them into the soil.

What is the maximum nitrite level in Ontario?

Nitrite moves much like nitrate in the soil and groundwater zones. The Ontario Drinking Water Standards (ODWS) set 1 mg/L (1 part per million) nitrite as nitrogen (NO 2-) as the maximum level for drinking water in Ontario. Nitrite levels in drinking water should not exceed this value.

Why is ammonium low in soil?

The concentration of ammonium in the soil is generally quite low (<1 mg/kg), because it is quickly converted to nitrate under conditions that are favourable for mineralization. The exception is where high rates of an ammonium fertilizer (anhydrous ammonia, urea or ammonium sulphate) or high rates of manure are applied.

How was nitrogen used in agriculture?

In order to effectively use nitrogen in agriculture, scientists first had to figure out how to mimic the fixation of nitrogen found in nature for commercial use. People began to understand the importance of fixed nitrogen for growing plants during the 19th century. Chilean saltpetre and ammonia collected from making coke fuel out of coal were first used in fertilizers. Heavy agricultural areas soon had a high demand for fertilizers containing fixed nitrogen compounds, which were intended as a supplement to the naturally existing supply. During this same time frame, the demand for Chilean saltpetre for use in gunpowder spiked. It was soon realized that existing supplies of the compound were inadequate to meet future demands, spurring a search across the globe for previously undiscovered reserves.

What is the reaction between nitrogen and calcium carbide?

In the second process (known as the cyanamide process), nitrogen is reacted with calcium carbide at high temperatures. The product of this reaction is calcium cyanamide, however, this product is further hydrolyzed to form ammonia and urea.

What is the nitrogen cycle?

The nitrogen cycle is the biogeochemical cycle responsible for cycling nitrogen amongst plants, animals, and the abiotic factors of their environment. The process is a natural component of the entire Earth system. Like most biogeochemical cycles, human activities are capable of altering the natural conditions of the nitrogen cycle. The two activities that are primarily responsible for these alterations are the use of fossil fuels and the addition of nitrogen to fertilizers. These activities have served to increase the amount of nitrogen biologically available in the environment.

What are the two activities that are responsible for the nitrogen cycle?

The two activities that are primarily responsible for these alterations are the use of fossil fuels and the addition of nitrogen to fertilizers. These activities have served to increase the amount of nitrogen biologically …

How does nitrogen affect the environment?

Nitrogen from fertilizers , most often in the form of nitrate, causes extensive environmental damage . Nitrogen is carried downward through soil or leaves Earth’s surface as runoff, it enters streams, rivers, lakes, groundwater, and oceans. It serves as a pollutant in human drinking water supplies and every ecosystem it enters.

How does nitrifying bacteria help plants?

Nitrifying bacteria will then convert the ammonia into nitrates, increasing the amount of nitrogen biologically available to plants. In conservation agriculture, crop rotation of legumes with non-leguminous plants is often used in to improve soil quality.

How does the addition of nitric oxides to the atmosphere affect the ecosystem?

Once the balance of natural nitrogen in the atmosphere has been lost, the ecology of entire regions can shift.

What happens to the nitrogen cycle?

The nitrogen cycle begins again as animal waste and decaying plants and animals deposit nitrogen into the soil, while precipitation deposits atmospheric nitrogen into the soil. Bacteria and algae once again convert nitrogen into ammonia, and the cycle continues.

How does nitrogen affect soil?

The nitrogen cycle is a natural process that adds nitrogen to the soil. However, the use of fertilizers has increased the amount of usable nitrogen in the soil. The extra nitrogen seems appealing from the agricultural viewpoint that more nutrients in the soil means higher yield crops. Unfortunately, ecosystems, including those created through crop production, have limited nitrogen needs. Excess nitrogen not taken up by plants and unable to be converted back into atmospheric form by bacteria leaches deeper into the soil and out of the cycle, contaminating groundwater supplies and encouraging the growth of toxic algae blooms.

How do bacteria absorb nitrogen?

Animals and other organisms absorb the nitrogen compounds by eating the plants or by eating other animals and organisms that ate the plants.

How much nitrogen is in the air?

By Elizabeth McNelis. Hunker may earn compensation through affiliate links in this story. Air is 78 percent nitrogen. Nitrogen is an important component in plant and animal proteins and, therefore, essential to all life. Although nitrogen is the most abundant element in the air, most organisms cannot use the nitrogen in the atmosphere.

What plants deposit nitrogen into the air?

Precipitation and legume crops like alfalfa and beans deposit nitrogen from the air into soils and waterways. Bacteria and algae combine the nitrogen with hydrogen, forming ammonia.

Can organisms use nitrogen?

Although nitrogen is the most abundant element in the air, most organisms cannot use the nitrogen in the atmosphere. The nitrogen cycle converts atmospheric nitrogen into a biologically usable form. However, this natural process can be negatively altered by the use of fertilizers. Advertisement.

How can we increase soil carbon stocks?

Integration of practices that can increase soil carbon stocks include maintaining land cover with vegetation (especially deep-rooted perennials and cover crops), protecting the soil from erosion (using reduced or no tillage), and improving nutrient management.

How does biofuel affect carbon?

A biofuel ’s carbon footprint depends on the feedstock and its associated management as well as the efficiency of the eventual energy produced from the feedstock. Changes in the management of these social and economic factors can affect soil carbon sequestration and storage and agricultural GHG emissions.

What is the net result of multiple fluxes?

Agricultural land carbon storage and loss are the net result of multiple fluxes including plant photosynthetic uptake (i.e., atmospheric CO 2 capture by plants), ecosystem respiratory loss (i.e., carbon released as CO 2 from plants and soil organisms), harvested biomass removal either by grazing or cutting, input from additional feeds, enteric methane (CH 4) production by livestock, and the return of manure by grazing animals or addition of manure or other carbon-rich fertilizer amendments to agricultural lands.

How are carbon budgets affected by human decisions?

Agricultural regional carbon budgets and net emissions are directly affected by human decision making. Trends in food production and agricultural management, and thus carbon budgets, can fluctuate significantly with changes in global markets, diets, consumer demand, regional policies, and incentives ( very high confidence).

What are the sources of CH4 emissions?

As previously discussed, enteric and manure fermentation are the sources of livestock CH 4 emissions. These two sources are affected by different factors and carry different levels of uncertainties. The U.S. EPA estimated 95% confidence interval lower and upper uncertainty bounds for agricultural GHG emissions at –11% and +18% (CH 4 emissions from enteric fermentation) and –18% and +20% and –16% and +24% (CH 4 and N 2 O emissions from manure management, respectively; U.S. EPA 2018). Whereas emissions from enteric fermentation are relatively well studied and predictable, there is larger uncertainty regarding manure CH 4 emissions and net effects of different intensities and types of grazing (see also Ch. 10: Grasslands ). Large datasets have established CH 4 emissions from enteric fermentation at 16 to19 g per kg dry matter intake for dairy cows (higher-producing cows have lower emissions per unit of feed intake) to 21 to 22 g per kg dry matter intake for beef cows on pasture (Hristov et al., 2013b). Levels of manure CH 4 emissions, however, largely depend on the type of storage facility, duration of storage, and climate (Montes et al., 2013). Emissions from certain dairy manure systems (e.g., flush systems with settling ponds and anaerobic lagoons) can be higher than estimates used by current inventories. So-called top-down approaches have suggested that livestock CH 4 emissions are considerably greater than EPA inventories. Miller et al. (2013) and Wecht et al. (2014) proposed that livestock CH 4 emissions may be in the range of 12 to 17 Tg per year, which is roughly 30% and 85% greater than EPA’s estimate for 2012 (U.S. EPA 2016). Thus, future research is needed to address these discrepancies and reconcile top-down and bottom-up estimates.


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