Nitrogen Fertilizer and Climate Change

In 2021, nitrogen fertilizer saw a huge price spike due to a string of severe weather events like Hurricane Ida and the February Texas cold snap. Alongside other supply-chain disruptions, these events have led to global shortages and decade-high consumer prices.

Most recent geopolitical tensions in Europe is expected to further escalated this issue, since both Russia and Ukraine are the large exporters of nitrogen products in the global market. In Canada, industry leaders are warning farmers to anticipate high fertilizer costs remaining for the rest of the growing season—an increase that is suspected to affect the entire food production system and lead to higher food prices everywhere.

These price spike comes just before spring and in the wake of 2021’s difficult year of droughts and flooding that has already affected profit margins. 

In this relentlessly challenging  environment, many farmers feel their crops  would be worse off if they reduced their nitrogen fertilizer use. Recent studies, however, have shown that nitrogen fertilizer application can be significantly reduced with little or no repercussions to yields or profit. In the midst of harsh conditions and uncertain times, cutting these costs can make a big difference to farmers’ bottom lines. 

So how has nitrogen fertilizer both helped and harmed Canadian farmers? Can we strike a balance to limit the use of nitrogen fertilizers or – better yet – remove them from the equation altogether?

The History of Nitrogen Fertilizer 

Nitrogen is key to plant growth. Both pasturelands and crops alike respond positively to the abundant presence of nitrogen. As an element, nitrogen is plentiful on earth; it makes up a little less than 80 percent of the air we breathe. However, atmospheric nitrogen is bound too tightly to be useful to plants. Certain plants like legumes have formed a symbiotic relationship with rhizobacteria that live around their roots. The bacteria convert atmospheric nitrogen into a usable form for the plant in exchange for carbon. However, for the majority of plants, nitrogen has to come from the soil in the form of nitrate. 

Soil-bound nitrate is actually quite rare. For farmers, figuring out how to cycle nitrogen effectively from the soil to the plants and back again has been a 10,000-year struggle. Even if farmers from the past didn’t know why it worked, they knew that adding compost and manure to a field produced better crops. 

In the nineteenth century, British scientists discovered that nitrogen was the key ingredient to plant growth. At the same time, German scientists Fritz Haber and Carl Bosch discovered the chemical reaction of nitrogen and hydrogen-based ammonia, which would become key to the production of nitrogen fertilizer. This energy-intensive process essentially drew nitrogen from the air to make nitrate, an amazing discovery that allowed Europe to feed its growing population. 

Without a doubt, modern agriculture would not be what it is today without the use of nitrogen fertilizers. However, farmers are starting to see the harmful effects of the abundance of synthetic nitrogen fertilizers and explore alternative solutions. 

Nitrogen Fertilizer’s Contribution to Climate Change 

Nitrogen emissions (also called nitrous oxide) exist as part of a natural nitrogen cycle. When nitrogen is released into the atmosphere, it stays there until it is drawn down by a sink or broken down through chemical reactions. However, industrial human activity has seriously increased nitrogen emissions, which are contributing to the climate crisis. 

Nitrous oxide is a potent greenhouse gas that makes up 5 to 7 percent of global greenhouse gas emissions. This may not seem like much, but it’s a major problem because nitrous oxide is 300 times more effective at trapping heat than carbon dioxide, and it remains in the atmosphere for 114 years. Nitrous oxide is also known to be an ozone layer-destroying gas. 

Recent studies from McGill University show that agriculture is the main contributor to Canada’s total nitrogen pollution—not just in the form of nitrous oxide emissions, but also water pollution. Nitrogen moves easily in water and nitrogen runoff can cause algae blooms that block sunlight and suck up the surrounding oxygen from the water. This creates dead zones—dark and barren underwater landscapes where no fish or vegetation can live. Runoff from mid-western American farms deposited into the Mississippi river has created a dead zone in the Gulf of Mexico that grew to 6,334 sq miles in 2021. 

Producing synthetic nitrogen fertilizers is a very energy-intensive process, powered by fossil fuels that add to the ecological damage of the fertilizer’s lifecycle. 

The main sources of nitrous oxide emissions are nitrogen fertilizers and animal manure. About 10 percent of direct emissions come from synthetic nitrogen fertilizer applied to crops. For instance, 72 percent of emissions from corn production (the most nitrate-demanding crop per acre) come from nitrogen inputs.This may seem like splitting hairs, but in 2017 Canada produced 13 million tons of CO2 equivalents through the application of fertilizers alone. This is equivalent to the effect of 2.7 million cars on the road for a year. 

Global nitrogen emissions are rising. A recent study found that nitrogen emissions have increased by over 30 percent over the past four decades, exceeding the emission rates calculated into worst-case climate crisis scenarios. The majority of these emissions come from agriculture, which underscores how important it is to find ways of curbing reliance on nitrogen fertilizer if we hope to protect our farms from the worst effects of climate change.  

It is estimated that 40-60 percent of nitrogen fertilizer placed on fields doesn’t actually make it into the soil, and instead escapes into the surrounding environment through runoff and air pollution. This number is expected to increase as the climate crisis makes floods and storms more severe and more frequent. Nitrogen pollution is a waste of money for farmers, so finding ways to eliminate or reduce that waste can be a major cost-saving opportunity for farmers as well as a chance to reduce a farm’s environmental impact.

In December of 2020, the federal government committed to reducing fertilizer emissions by 30 percent below 2020 levels by 2030 by developing policies that would limit emissions while maintaining crop yields. How can farmers work to meet those targets? And if we know nitrogen pollution is harmful to plants, farmers and the environment, is there a way to completely eliminate it from farming systems?

Ways to Reduce Nitrogen Emissions  

There are several ways that farmers can reduce or eliminate the use of nitrogen fertilizer.

Controlled Application

For many farmers, removing nitrogen entirely from their agricultural system is out of the question. However, it’s possible to reduce emissions and pollution without affecting yields or profits through tightly controlled applications that consider the Four Rs:  

Right source: Using the appropriate chemical form and formulation can increase crop-produced nitrate and reduce the amount of nitrogen lost to the surrounding environment. For instance, replacing anhydrous ammonia with other nitrogen formulations can significantly reduce emissions. 

Right rate: It is important to only apply the minimum amount of nitrogen needed to meet growth targets. Many farmers apply extra nitrogen as “insurance” for highest-possible yields, but this practice is costly and unnecessary since excess nitrogen leaches off the fields and pollutes the surrounding environment. Overapplication also has negative consequences for crops. An oversupplying of nitrogen has been linked to lowered plant immunity and weak and brittle plant stalks. Finding the right amount of nitrogen to apply to the field is vital but tricky. Necessary nitrogen levels may vary due to weather, crop types and management styles. Using adaptive in-season N rate and timing tools can help farmers calculate the exact amount of nitrogen fertilizer needed for a particular growing season.

It is also important to consider how nitrogen may be drawn from other sources. Manure, plant residue and cover crops may be applied to a field to increase nitrogen levels. Farmers rarely take these sources into consideration when calculating how much nitrogen they need, and as a result, usually overestimate the amount of nitrogen their fields require. 

Right time: Timing is very important in reducing nitrogen loss. Do not apply nitrogen fertilizer in the fall for spring crops, since most of it will be lost over the winter and early spring as a result of precipitation. Instead, apply nitrogen fertilizer to the field as close to the time of maximum growth of the crop as possible. For crops such as corn, applying starter nitrogen at planting and side-dressing the remainder of the season will help to cut down on nitrogen loss. Farmers can check the forecast before applying fertilizers to ensure there is no expected rain for at least seven days after farmers intend to apply the fertilizer. This will ensure the least amount of nitrogen loss possible. 

Right place: When fertilizers are incorporated into the soil instead of placed on top of the soil, losses due to volatilization are reduced, particularly the loss of ammonia. However, incorporating fertilizers into the soil can also increase nitrogen loss in certain cases, so it is important to take the other Rs into consideration in order to effectively reduce nitrogen loss. 

Using these four Rs together can help create a comprehensive plan to reduce nitrogen loss. 

Nitrogen Stabilizers  

As farmers know, weather is unpredictable. Nitrogen stabilizers are an excellent option to help curb nitrogen emissions when precipitation is unavoidable. There are three kinds of nitrogen stabilizers: 

  •  Nitrification inhibitors are compounds mixed with ammonium-forming N fertilizers to decrease the rate of transformation of ammonium to nitrate. Both ammonium and nitrate are available to the plants to use as food, but only nitrate moves well in water. When using inhibitors, it is important to note that they are only expected to have a positive impact on grain yield when weather patterns favor losses large enough that nitrogen becomes insufficient to meet crop needs.
  • Urease inhibitors are compounds mixed with urea-based fertilizers to decrease the rate of urea hydrolysis. They can be especially effective at reducing loss when they are applied to the surface of high-pH soil, and in high-residue conditions such as no-till.
  • Slow-release coated fertilizers are conventional fertilizers like urea that are coated with sulfur, polymers or both. The coating technology can provide a gradual supply of nitrogen for the developing crop. 

Choosing to use stabilizers can be a complicated process. Nitrogen stabilizers will only have a positive impact (and be worth the extra cost) if the farmer knows that weather conditions of the growing season will be conducive to nitrogen loss. Nitrogen inhibitors are the most effective when applied in May or June.

Appropriate Manure Management to reduce Nitrogen and Methane emissions 

When discussing agricultural emissions, it’s necessary to address the cow in the room. Manure also serves as a source of nitrogen emissions (as well as methane and ammonia emissions). There are a few tactics that farmers should consider when applying manure: 

  • Rapid incorporation into the soil to avoid loss of ammonia is important, and rates of manure should not exceed the nutrient requirements of the crop. 
  • Manure should be tested for nutrient content, not just nitrogen levels but other nutrients, like phosphorus, so that the proper amount of manure can be applied for the crop. 
  • Manure can’t be applied to frozen ground, since it will mostly run off into the surrounding environment.
  • Avoid adding straw to manure because straw acts as a food source for anaerobic bacteria which cause higher emissions levels 
  • Apply manure to the soil as soon as possible. Storing manure for long periods of time can encourage anaerobic decomposition and result in increased emissions. 
  • Avoid manure application when the soil is wet, as this leads to anaerobic conditions and increases emissions.
  • If you are using manure from your own livestock, try adding edible oils like canola or coconut oil to the animals diet. The added oil will reduce rumen bacteria and emissions. 

All of these strategies can be effective at reducing emissions and pollution from nitrogen fertilizers. However, to minimize environmental damage and maximize crop yields fertilizer and manure application needs to be just one part of a crop rotation and cover cropping system that prioritizes soil health and avoids leaving the soil bare. When the soil is taken care of, the soil will take care of the plants in return.

  • Rebuilding soil structure: Organic fertilizer is rich in organic matter, which helps to build soil health. Having healthy soil comes with massive benefits, including more resilient crops, carbon sequestration and  reduced soil erosion. 
  • Reducing the reliance on fertilizers and pesticides in general: While organic fertilizers still emit nitrous oxide, they do so at a lower rate than synthetic fertilizers. Organic fertilizers allow the soil to replenish its natural stock of nutrients for plants to draw from. This reduces the overall need for things like fertilizers and other chemical inputs such as pesticides and herbicides (which have also seen a price spike in 2021), further cutting down on costs. 
  • No threat of damaging plants: Over-application of synthetic fertilizers can actually harm the plant and salinate the ground, but organic fertilizers pose no threats to the plants and over-application of organic fertilizers is unlikely.

Without nitrogen fertilizers, we wouldn’t be where we are today. They have helped us feed millions of people at a low cost for centuries, but now we are experiencing the effects of this over-reliance of nitrogen on our agricultural system and the planet. Our soil is degraded and eroding, our waters are polluted and rising greenhouse gas emissions worsened growing conditions for farmers all over the world. 

Our agricultural system was not designed to limit our nitrogen fertilizer use, but it can be. With the right management, farmers can curb pollution, maximize yields and feed their communities without sacrificing profits. 
Throughout this series we have focused primarily on Canada—but what is the rest of the world doing to promote organic regenerative agriculture, and how can we learn from those approaches? Check out our next article, which explores the organic sector in different parts of the world, to learn more.

This knowledge article is part of our Organic Climate Solutions campaign. Check out OCO’s Organic Climate Solutions campaign, funded in part by the Government of Canada, to learn more about how farmers can reduce the environmental impact of agriculture and be part of the climate solution.

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