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Nitrogen Use Efficiency (NUE)
Indian research can help cut nitrogen fertiliser waste
WHY IN NEWS:
- Indian scientists manage to identify phenotypes, visibly identifiable features that determine the efficiency with which cultivars use nitrogen
- A group of Indian scientists have found a way to improve crops by reducing wastage of nitrogen fertilisers applied to them.
- The research involving interdisciplinary research in biotechnology, crop physiology, agronomy, soil science, statistics and bioinformatics was published in journal Frontiers in Plant Science January 20, 2021.
SYLLABUS COVERED: GS 3: Agriculture : Chemistry : Nitrogen Cycle
NITROGEN-USE EFFICIENCY (NUE)
Scientists were able to identify phenotypes, or visibly identifiable features that determine the efficiency with which cultivated rice varieties (cultivars) use nitrogen.
Scientists also identified genes associated with the identifiable features that can improve crops further.
Crops generally use up 30 per cent of nitrogen fertiliser applied; the rest seeps into the environment, harming health and adding to climate change.
WHAT IS NITROGEN USE EFFICIENCY?
Improving a plant’s ability to utilize nitrogen is a key component in enhancing environmental sustainability.
Today, improved plant breeding through the use of genetic engineering has the greatest potential to produce plants that will utilize fertilizer more efficiently than conventional varieties.
SIGNIFICANCE OF NUE
Plants need nitrogen to grow, develop and produce usable products.
Since plants get their nitrogen from the soil, farmers must replenish nitrogen to ensure successful growth and to replace nitrogen removed in the harvested crop.
Nitrogen is generally applied to the soil through various types of fertilizers.
Due to the substantial yield increases resulting from fertilization, farmers have steadily increased the amount of fertilizer added per unit of land area.
With the efficiency on the decline, farmers use more fertiliser in the hope of raising yield. This in turn worsens NUE.
WHAT HAPPENS IF PLANTS DON’T HAVE ENOUGH NITROGEN?
When plants are not provided with sufficient nitrogen, they become nitrogen deficient.
Plants with nitrogen deficiency often have spindly stems and their growth is stunted.
NITROUS OXIDE EMISSIONS IN INDIA
Agriculture leads to 70 per cent of nitrous oxide emissions in India.
Of this, 77 per cent is contributed by fertilisers, mostly urea, according to the Indian Nitrogen Assessment published in 2017.
This greenhouse gas (GHG) is 300 times more potent than carbon dioxide.
It has replaced methane as the second-largest component of GHG emissions from Indian agriculture in past 15 years.
Cereals consume over 69 per cent of nitrogen fertilisers in India; rice tops the list with 37 per cent, followed by wheat (24 per cent).
The scientists’ group compared three each of high- and low-NUE rice cultivars with normal or low doses of fertilisers like nitrate and urea as the sole nitrogen source.
Nitrogen-use efficient cultivars tend to germinate and flower slower they found.
Such varieties grow tall and deep, have a higher biomass and take longer for harvest; but they yield more on relatively less nitrogen.
Crop-improvement mostly focuses on reducing crop duration and biomass to maximise output.
We also need to worry about whether this is also true for other inputs such as phosphorus, water, potassium, sulphur, etc.
India was the first country to study 25 phenotypic features in any crop, comparing different cultivars, nitrogen-forms and doses.
Scientists found that only 20 of them respond to nitrogen-fertiliser while only eight actually account for NUE.
As paddy consumes the most nitrogen fertiliser in India, any improvement in its NUE will be a win-win situation.