Why does soil need nitrates

But as with everything, balance is key: too little nitrogen and plants cannot thrive, leading to low crop yields; but too much nitrogen can be toxic to plants, and can also harm our environment. Plants that do not have enough nitrogen become yellowish and do not grow well and can have smaller flowers and fruits.

Farmers can add nitrogen fertilizer to produce better crops, but too much can hurt plants and animals, and pollute our aquatic systems. Understanding the Nitrogen Cycle—how nitrogen moves from the atmosphere to earth, through soils and back to the atmosphere in an endless Cycle—can help us grow healthy crops and protect our environment.

Nitrogen, or N, using its scientific abbreviation, is a colorless, odorless element. Nitrogen is in the soil under our feet, in the water we drink, and in the air we breathe. Nitrogen is important to all living things, including us. 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. The delicate balance of substances that is important for maintaining life is an important area of research, and the balance of nitrogen in the environment is no exception [ 2 ].

When plants lack nitrogen, they become yellowed, with stunted growth, and produce smaller fruits and flowers. Farmers may add fertilizers containing nitrogen to their crops, to increase crop growth.

Without nitrogen fertilizers, scientists estimate that we would lose up to one third of the crops we rely on for food and other types of agriculture. But we need to know how much nitrogen is necessary for plant growth, because too much can pollute waterways, hurting aquatic life.

Nitrogen is a key element in the nucleic acids DNA and RNA , which are the most important of all biological molecules and crucial for all living things. DNA carries the genetic information, which means the instructions for how to make up a life form.

When plants do not get enough nitrogen, they are unable to produce amino acids substances that contain nitrogen and hydrogen and make up many of living cells, muscles and tissue. Without amino acids, plants cannot make the special proteins that the plant cells need to grow. Without enough nitrogen, plant growth is affected negatively. With too much nitrogen, plants produce excess biomass, or organic matter, such as stalks and leaves, but not enough root structure. In extreme cases, plants with very high levels of nitrogen absorbed from soils can poison farm animals that eat them [ 3 ].

Excess nitrogen can also leach—or drain—from the soil into underground water sources, or it can enter aquatic systems as above ground runoff. This excess nitrogen can build up, leading to a process called eutrophication. Eutrophication happens when too much nitrogen enriches the water, causing excessive growth of plants and algae. When the phytoplankton dies, microbes in the water decompose them. Organisms in the dead zone die from lack of oxygen.

These dead zones can happen in freshwater lakes and also in coastal environments where rivers full of nutrients from agricultural runoff fertilizer overflow flow into oceans [ 4 ].

Can eutrophication be prevented? People who manage water resources can use different strategies to reduce the harmful effects of algal blooms and eutrophication of water surfaces. They can re-reroute excess nutrients away from lakes and vulnerable costal zones, use herbicides chemicals used to kill unwanted plant growth or algaecides chemicals used to kill algae to stop the algal blooms, and reduce the quantities or combinations of nutrients used in agricultural fertilizers, among other techniques [ 5 ].

But, it can often be hard to find the origin of the excess nitrogen and other nutrients. Once a lake has undergone eutrophication, it is even harder to do damage control. Algaecides can be expensive, and they also do not correct the source of the problem: the excess nitrogen or other nutrients that caused the algae bloom in the first place!

Another potential solution is called bioremediation , which is the process of purposefully changing the food web in an aquatic ecosystem to reduce or control the amount of phytoplankton. For example, water managers can introduce organisms that eat phytoplankton, and these organisms can help reduce the amounts of phytoplankton, by eating them! The nitrogen cycle is a repeating cycle of processes during which nitrogen moves through both living and non-living things: the atmosphere, soil, water, plants, animals and bacteria.

The differences between nitrification when ammonia is converted to nitrates , and denitrification are examined through looking at different soil moisture contents and varying carbon to nitrogen ratios C:N to determine the potential switch between the utilisation of fertiliser nitrates and native nitrates. Ultimately this project will lead to a better understanding of nitrous oxide emissions, improved nutrient management and possibly less reliance on fertiliser nitrates. Why is Nitrogen important?

The key factors are: Nitrogen residues leftover from previous fertiliser applications Nitrogen residues from previous organic manure applications Soil type and organic matter content Losses of nitrogen by leaching and other processes Nitrogen made available for crop uptake from mineralisation of organic material during the growing season There are two methods of determining the SNS Index of a field: Field Assessment Method — based on field specific information e. The three key inputs of nitrogen N for plant growth are: Atmospheric N — made available through legumes Artificial fertiliser Organic sources — includes soil organic matter, crop residues and manures.

These organic sources must be converted to inorganic forms of N through decomposition by microorganisms. Nitrogen can be lost from the soil through: Leaching — water soluble nitrates move out of soil with excess water Denitrification — primarily occurs in anaerobic i.

Nitrates in the soil can originate from three different sources: 1. What does this mean for farmers? Shake for 1 minute. Allow the sample to settle for 5 minutes or filter it using filter paper and funnel. Sample Measurement Place some drops of unused water or extractant into the sensor.

Record the reading as the blank. Blank is only required once for each batch of samples. Rinse the sensor with water and blot it dry with tissue. Place some drops of clear liquid taken from the top layer of soil extract or filtrate, if filtered sample.

Record the reading once stabilized. After each sample, rinse the sensor with water and blot it dry with tissue. Collect dry soil samples and pass through a 2mm sieve. Supplementary Information Soil — Wet samples will need to be air dried by spreading thin layer of soil in a sheet of plastic under the sun. Samples that have too much clay will need to be crushed. Extractant - Water or dilute salt solutions can be used to extract nitrate from most soils because essentially all the nitrate in soils with low anion exchange capacities is water soluble.