Use of Novel Nitrogen Management Technology to Mitigate Greenhouse Gas Emissions

Carbon footprint of agriculture
 

Greenhouse gases act as a barrier that traps the sun’s heat in the earth atmosphere much the same as a greenhouse roof. Common greenhouse gases are methane, carbon dioxide, nitrous oxide and water vapor. During the pre-industrial era, there was a balance of greenhouse gases present in the atmosphere due to natural mechanisms, such as photosynthesis, that removed any excess gases.  Over the last 100 years, population increase, higher gas consumption, deforestation and intensive agricultural practices have led to the release of much larger quantities of greenhouse gases into the earth’s atmosphere. Today, the earth’s atmosphere contains 42 % more CO₂ than it did in the pre-industrial era (1800s). Additionally CO₂ levels have increased from 280 ppm in the pre-industrial era to 400 ppm today. This man-made phenomenon has resulted in the planet warming by 1.5℃ more than pre-industrial levels, a faster rate than scientists’ earlier predictions of 1℃.
 

The world population grew from 1.65 billion in 1900 to 7.7 billion in 2020 and continues to grow. To meet the food requirements of the future, enhanced agricultural productivity is essential. Nitrogenous fertilizer is a large portion of the total fertilizer applied and plays a major role in population growth. It is estimated that 48% of global population is fed by synthetic nitrogen fertilizer. The contribution of nitrogenous fertilizer to population growth is shown in Figure 1.
 

 

Figure 1. World population with and without synthetic nitrogen fertilizer
 

The increased use of synthetic nitrogen fertilizer is one of the important contributors to increased N₂O emissions in recent decades. The agriculture sector represents the world’s second-largest greenhouse gas emitter at 24%. Nitrous oxide (N₂O) and methane (CH₄) are the two most important greenhouse gases emitted by the agriculture sector. Figure 2 shows the contribution of each sector for greenhouse gas emissions globally.

 

 

Agriculture plays a major role in global nitrous oxide emissions creating 4.5 million tons of nitrous oxide per year, the equivalent of 1.4 billion tons of CO₂. According to the Figure 3, agriculture represents 67% of the total nitrous oxide emissions while fertilizer and manure represents 42% of this value. Soil microbial activity converts part of nitrogen present in nitrogenous fertilizer to nitrous oxide.

Figure 3. Global Nitrous Oxide emissions. 

Urea and greenhouse gas emissions:

Urea is the most common primary source of nitrogen fertilizer applied in all cropping systems. The use of urea has increased dramatically in the past 20 years and now has become the largest volume fertilizer in the world. Currently annual consumption of urea (as a fertiliser) sits at 160 million MT and will continually increase due to food necessities of increasing populations.

 

Once applied to the soil, the urea molecule is subject to hydrolysis, nitrification and denitrification (figure 4). Urea hydrolysis and denitrification release the greenhouse gases carbon dioxide and nitrous oxide. Ammonia generated through hydrolysis process can later convert into nitrous oxide.
 

The application of urea fertilizer presents the following major challenges:
 

1.Once applied to the soil, ammonia volatilization through hydrolysis by urease enzymes causes 30-50% of nitrogen present in the granule to be lost to the atmosphere without having any impact on crop growth.
2.Part of the nitrogen converts into nitrates and then to nitrous oxide, which is a potent greenhouse gas.
3.Loss of nitrogen through nitrification and denitrification is estimated to be 0.7% of the applied nitrogen.
4.Nitrous oxide is 298 times more potent than carbon dioxide as a greenhouse gas.
5.Nitrates are also less stable in the soil and subject to leaching and runoff into ground water.  This results in eutrophication, algal bloom and pollution of ground water.

All the above processes reduce the efficacy of nitrogen present in the urea granule while negatively affecting the ecosystem. It is important to address nitrogen loss from fertilizer and deploy technologies to mitigate this process.
 

Urease inhibitors and Nitrification/Denitrification inhibitors are used successfully to minimize loss of nitrogen through these processes. Total nitrogen losses can be reduced by 70-95%, thereby reducing ammonia volatilization, greenhouse gas emissions, leaching and runoff into ground water. Variations in losses due to ammonia volatilization are dependent on the soil chemistry (soil pH, Cation Exchange Capacity), soil organic matter content, soil moisture, microbial community and external factors such as wind. Soil pH is directly proportional to ammonia losses. Soil moisture also increases the losses and soils with higher cation exchange capacities reduce the losses. Anaerobic conditions (poorly drained soil) enhance nitrous oxide emission.
 

N-(n-butyl) thiophosphoric triamide (NBPT) is one of the most commonly used urease inhibitors.  Dicyandiamide (DCD), Nitrapyrin and 3, 4-Dimethylpyrazole phosphate (DMPP) are three commonly used nitrification and denitrification inhibitors. These compounds have been proven to mitigate both ammonia volatilization and the nitrification-denitrification processes.
 

Saved nitrogen is utilized by crops and is usually reflected in yield gain. Farmers benefit from using nitrogen saving technologies by either harvesting a higher yield or reducing nitrogen fertilizer applications to achieve the same yield. More importantly, these management practices help reduce greenhouse gas emissions and ground water pollution.
 

Arm U/Advanced, a patented technology developed by Active AgriScience (https://activeagriscience.com/), contains NBPT as a urease inhibitor and DMPP as a nitrification-denitrification inhibitor. Efficacy of Arm U/Advanced is supported by five years of third-party research data from Canada, USA and Australia.

 

Features of the technology

1.Excellent flowability
2.No smell
3.pH buffered
4.good coverage on the urea granule
5.Dust reduction
6.Wide temperature handling capabilities (-10°C to 45°C)
7.No caking or build-up in blending equipment
 

Benefits to farmers

1.Increased stewardship in nutrient management
2.Increased yield
3.Increased return on Investment (ROI)

Benefits to crops

1.Enhanced nitrogen utilization efficiency as nitrogen stays longer in the soil
2.Increased yield across many different crops - corn, wheat, canola etc.
3.Enhanced yield quality due to increased protein content

Benefits to the environment

1.Reduced leaching of nitrates due to the inhibition of soil nitrification
2.Reduced water pollution by nitrates
3.Reduced emissions of greenhouse gases (nitrous oxide) into the atmosphere
 

Third party greenhouse and field efficacy trials of Arm U/Advanced were conducted by the University of Manitoba (Manitoba, Canada), the University of Winnipeg (Manitoba Canada), United Prairie LLC (Illinois USA) and MEAG Soil Consultancy (Goomalling, Western Australia). Results show that Arm U/Advanced can reduce nitrogen losses as ammonia by 70-95% (Table 3), increase corn yields by 503-808 kg/Ha, wheat yields by 337-808 kg/Ha and canola yields by 168-393 kg/Ha (Table 4). In these research trials, the return on investment was 5-7 times the initial investment.
 

Treatment	Corn		Wheat		Canola
	Yield (Kg/Ha)	Yield Increase (Kg/Ha)	Yield (Kg/Ha)	Yield Increase (Kg/Ha)	Yield (Kg/Ha)	Yield Increase (Kg/Ha)
Untreated Urea	14,404.1		2,889.9		2,509.3
Treated Urea (Arm U Advanced)	15,149.8	735.6	3,381.7	491.8	2,750.7	241.4

Table 4. Ammonia volatilization reduction with Arm U Advanced. Applied nitrogen: 168Kg/Ha.

Treatment	Total Ammonia Loss (Kg Nitrogen/Ha)	Kg of Nitrogen Savings/Ha	Kg of Urea Savings/Ha
Untreated Urea	35.8
Treated Urea (Arm U Advanced)	7.0	28.8	68.7

Coating urea granules with Arm U/Advanced technology can be done easily by the urea manufacturer or a local distributor. The active molecules present in Arm U Advanced, penetrate into the urea granule while in storage, increasing its efficacy. Once treated, urea can be used within a year, giving greater flexibility in inventory control and handling.
 

Proposing carbon tax on untreated urea:
 

Considering the relative ease of adopting the technology, coating urea with urease / nitrification / denitrification inhibitors is a viable way to tackle one of the largest contributors of greenhouse gases and water pollution. Governments who are keen to mitigate greenhouse gases should strongly consider legislating these practices or at least the coating of urea to achieve similar outcomes.
 

Table 5. shows the economics of nitrogen savings and the reduction of greenhouse gas emissions by Arm U Advanced for a urea treatment plant of 100,000 MT / year capacity. Nitrogen loss due to ammonia volatilization is assumed to be 35%. This loss can vary up to 50% of the applied nitrogen. Nitrogen savings by adopting Arm U Advanced technology is assumed to be 70% of the lost nitrogen. These savings can be as high as 95% of the lost nitrogen. Nitrous Oxide emission is assumed to be 1% of the applied urea.

 

Table 5. Ammonia volatilization, nitrous oxide emissions from untreated urea and savings due to Arm U Advanced for a urea manufacturing plant with 100,000MT capacity.

Ammonia Volatilization, nitrous oxide emission and equivalent Carbon Dioxide Calculations for a Urea Manufacturing Plant with 100,000MT/YEAR Capacity
Plant Capacity -Urea (MT)/annum	100,000.00
Total Manufactured Nitrogen (MT)/annum	46,000.00
Nitrogen Loss due to Ammonia Volatilization  (MT)/annum	16,100.00
Nitrogen Loss as Nitrous Oxide (MT)/annum	460.00
Nitrogen Loss due to Nitrate Leaching	920.00
Total Nitrogen loss (MT)/annum	17,480.00
Minimum Nitrogen savings by Arm U Advanced technology (MT)/annum	12,236.00
Minimum Nitrogen Savings in terms of Urea by Arm U Advanced Technology (MT/annum)	26,600.00
Total greenhouse gas emission savings equivalent to Carbon Dioxide (MT)/annum	137,080.00
Total emissions equivalent to CO2	51,500,000.00
% Reduction	27%

Based on the calculations, Arm U Advanced is able to save conservatively 7.7 million MT of CO2 equivalent greenhouse gases per year when manufacturing 5.6 million MT of urea.  Additionally, Arm U Advanced will help reducing ground water pollution through nitrate leaching and enhance crop productivity and quality. The economic value of carbon tax remittance can vary between $77-$231 million USD considering $10 - $30.00 USD/MT of emitted CO2. The cost of treating urea with Arm U Advanced is $135 million USD. The treatment cost is particularly attractive considering the yield advantage of 335 kg / hectare for corn, 200 kg / hectare for wheat and canola aside from the carbon tax remittances. The final return on investment (ROI) can vary between 5-10 times depending on yield advantage and crop values.

Nitrogen management is one of the major tools that can be implemented without delay to mitigate greenhouse gas emissions and reduce the impact of global warming while maximizing crop quality and yield potential, thereby optimising economic gains to farmers.

Conclusions:

1.Greenhouse gas emission and global warming is no longer an issue of any single country or region.   Actions to curb emissions and preserve the sustainable ecosystems for future generations is a responsibility of the current generation and needs to come from every citizen of the Earth led by responsible governments.
 

2.Taxing emissions is only one solution out of the many solutions available to curb the climate issue.
 

3.Proposing a tax on untreated urea is a meaningful way of curbing greenhouse gas emissions and will significantly cut down nitrous oxide emissions.