Indian Biotechnologists have discovered a wide variation among popular varieties of rice in India in their ability to use nitrogen.
Nitrogen Use Efficiency
- It is used to describe the efficiency of a plant in using applied or fixed nitrogen for biomass production.
- It is further defined as the ratio between crop yield and the amount of nitrogen absorbed from the soil through roots or from the atmosphere through fixation by bacteria.
- NUE in cereals, particularly rice, is a critical factor in agricultural sustainability.
Concerns
- Poor NUE wastes Nitrogen fertilisers worth Rs 1 lakh crore a year in India and over USD 170 billion per year globally.
- Nitrogen fertilisers are the main source of nitrous oxide and ammonia pollution of air and nitrate/ammonium pollution of water, affecting our health, biodiversity, and climate change.
- India is the world’s second-largest source of nitrous oxide (N2O), a greenhouse gas that heats up the atmosphere far more than carbon dioxide.
- In 2020, nearly 11% of such global man made emissions were from India, next only to China (16%). The major source of these emissions is fertiliser usage.
Nitrogen Use Efficiency (NUE)
- Nitrogen use efficiency refers to the yield of a crop relative to the nitrogen (natural and artificial) available to it.
- It is defined as the ratio of the amount of nitrogen effectively utilised by crops to the amount of nitrogen applied. It measures how well a plant uses nitrogen for growth and productivity.
Factors Affecting Nitrogen Use Efficiency (NUE)
- Genetics: Plant variety impacts NUE, influencing overall nitrogen utilisation efficiency.
- Soil Conditions: Soil type and health affect nitrogen uptake, impacting crop yields and fertiliser needs.
- Fertiliser Application: Type, timing, and method of application influence efficiency, affecting input costs and environmental impact.
- Crop Management: Practices like rotation and cover cropping improve NUE, enhancing productivity and reducing waste.
- Environmental Conditions: Weather and climate affect nitrogen utilisation, influencing plant growth and nutrient availability.
- Soil Microbes: Microbial activity affects nitrogen availability, influencing overall nutrient uptake and plant health.
Background Context
- Historical Focus on Yield: Indian agriculture has historically prioritised yield over NUE, leading to increased synthetic fertiliser use and associated pollution.
- Lack of Variety Ranking: India lacks a ranking system for crop varieties based on NUE, hindering crop improvement through selection or breeding.
- Urea Consumption in India: Two-thirds of all urea in India is consumed by cereals, with rice being the primary contributor.
- Economic Impact: Poor nitrogen-use efficiency (NUE) in rice leads to wastage of urea worth ₹1 trillion annually in India and over $170 billion globally.
- Environmental Concerns: Nitrogen fertilisers are major sources of nitrous oxide (N2O) and ammonia pollution, impacting health, biodiversity, and climate change.
- Greenhouse Gas Emissions: India is the world’s second-largest emitter of nitrous oxide (N2O), largely due to fertiliser use, contributing significantly to global greenhouse gas emissions.
- Global Commitments: India is a signatory to the Kunming-Montreal Global Biodiversity Framework (2022), which mandates countries to halve their nutrient waste from all sources by 2030.
Nitrogen (N)
- Nitrogen, the predominant gas in Earth’s atmosphere, is crucial for life as it is found in soil, food, and our DNA.
- Nitrogen (N) is considered as an essential Macronutrient.
- A macronutrient is one of the essential nutrients required by plants in relatively large quantities for their growth and development.
Significance of Nitrogen
- It is essential for proteins, enzymes, chlorophyll, and DNA in plants, supports photosynthesis, amino acid production, and vital plant structures.
- Insufficient nitrogen leads to stunted growth, yellowing leaves, and reduced yields.
- Nitrogen fixation: Despite constituting 78% of the atmosphere, most organisms cannot directly utilise atmospheric nitrogen, necessitating conversion processes like nitrogen fixation.
- Nitrogen fixation is the process by which nitrogen is taken from its molecular form (N2) in the atmosphere and converted into nitrogen compounds useful for other biochemical processes.
- Fixation can occur through atmospheric (lightning), industrial, or biological processes.
Nitrogen Pollution
- It refers to the excessive presence of nitrogen compounds in the environment, often resulting from human activities such as agriculture, industrial processes, and transportation.
- This surplus of nitrogen can lead to various environmental problems, including water contamination, air pollution, and disruption of ecosystems.
Sources of Nitrogen Pollution
- Agricultural Fertilisers: Overuse leads to nitrous oxide emissions, a potent greenhouse gas.
- Sewage: Contributes to nitrogen pollution when not properly treated.
- Food Waste: High in nitrogen, originating from both human and animal sources.
- Wastewater Treatment: Facilities without nitrogen removal processes can elevate nitrogen levels in water.
- Stormwater Runoff: Urban runoff carries nitrogen and phosphorus from roads and rooftops to water bodies.
- Fossil Fuel Usage: Diesel vehicles, despite cleaner technologies, still contribute to nitrogen pollution.