Category Environment

What are the alternative options available for stubble burning?

Farmers can use devices such as mulchers (that cut up grass, leaves, etc., for use as mulch), rotavators (a machine with rotating blades for breaking up or tilling the soil), Happy Seeders and straw management system to manage and utilise stubble.

Happy Seeder is nothing but a tractor-mounted device which can cut and lift the previous crop (in this case the rice straw) and sow a new (wheat) crop in its place simultaneously. It also deposits the straw over the sown area as mulch. Mulch enriches and insulates the soil.

The straw management system involves the use of a machine attached to a harvester chopper, which spreads loose straw uniformly. Here, the straw serves as mulch.

Straw could also be used as feeder.

(However, farmers in these regions report a lower preference for paddy straw because of the comparatively high silica content in it. There are also reports of wheat straw rejection due to fuel spillover during harvesting by machines.)

 

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Why do farmers resort to stubble burning?

Farmers have to clear the stubble soon after harvest so as to prepare the field for sowing the next crop.

For clearing the farm waste, they usually have a short span of 10 to 15 days during which they prefer burning the stubble to other methods as it is considered the cheapest and least time-consuming solution. The residue and stubble are an important source of organic matter for the soil. Burning off this organic matter will gradually reduce soil organic matter levels. Burning can made the soil hotter and drier on the surface, creating a hard seedbed. Burning can temporarily seal the soil surface to some extent. Burning will result in the loss of some of the volatile nutrients, such as nitrogen, in the residue. Phosphorus and other minerals are not volatilized by burning and will remain on the field in the ash, unless the ash is blown away.

 

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What is stubble burning?

The air quality in Delhi and other parts of north India hit a hazardous level this month. Levels of dangerous particles in the air – known as PM2.5 – were over 10 times the safe limits in the capital. The air quality index (AQI) crossed an all-time high of 1,000 in some places on November 3. As per data, the AQI between 0 and 50 is considered safe, 51-100 satisfactory, 101-200 moderate, 201-300 poor. At 301-400 it’ considered very poor and 401-500 falls in the severe category. When the AQI crosses the 500 mark, it falls into the emergency category.

The odd-even rule, a car rationing scheme, came into effect on November 4. (As per rule, cars with odd numbers will be allowed to run on odd days such as Nov 5, 7 etc., and cars with even numbers will be allowed on even days such as Nov 6, 8, etc.). Delhi Chief Minister Arvind Kejriwal blamed crop burning in Haryana and Punjab for increased pollution levels in the capital during winter.

Air pollution is a year-round problem in Delhi due to vehicular and industrial emission, but the impact is felt more during the winter months. The capital’s low air quality during the winter is attributed to its geography, low wind speed and stubble burning by farmers in the neighbouring States of Punjab and Haryana. These farmers have come under fire for taking the air quality to a dangerous level.

Stubble burning is the practice of removing crop residue from fields post-harvest by setting fire to it. This usually happens during October and November (autumn months), as the farmers begin to prepare the field for sowing winter crops – especially wheat.

As the southwest monsoon retreats, it sets off northwesterly winds, which carry the smoke from the burning of stubble towards Delhi and other northern regions.

According to the agriculture ministry, 23 million tonnes of paddy straw is burnt in Punjab, Haryana and UP every year.

 

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How do they measure sea level?

Tide gauge is among the oldest methods to measure sea level. A tide gauge is fitted with sensors and placed on piers. It continuously records the height of the surrounding water level. Water older tide-measuring stations used mechanical floats and recorders, modern monitoring stations use advanced acoustics and electronics. Sea level is also measured from space using laser altimeters, which determine the height of the sea surface by measuring the return speed and intensity of a laser pulse directed at the ocean. The higher the sea level, the faster and stronger the return signal is.

You can see that getting an accurate reading (for example, down to the millimeter level) is extremely difficult. Satellites are now used as well, but they suffer from many of the same problems. Scientists do the best they can, using extremely long time spans, to try to figure out what the sea level is and whether or not it is rising. The general consensus seems to be that the oceans rise about 2 millimeters per year.

 

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What are the impacts of sea-level rise on coastal region?

  • The impact of sea-level rise includes flooding, habitat destruction and salt water intrusion in coastal areas, increased soil erosion and disappearance of low-lying islands. Rising sea levels also make storm surges capable of much greater damage. (Storm surge is the abnormal rise in seawater level during a storm. Storm surge can penetrate well inland.)
  • Higher sea levels are coinciding with more hurricanes, contributing to more powerful storm surges that can strip away everything in their path.
  • Saltwater intrusion is the flow of seawater into water bodies such as rivers and aquifers (underground water bearing rocks). It is a major concern as it can induce contamination of water resources, used for drinking, household purposes and agriculture. Increased salinity of coastal freshwater can threaten vegetation and wildlife of the region.
  • Many birds use coastal ecosystems to find food, live and breed. Sea turtles lay their eggs on beaches, returning to the same location every year. When beaches erode, these animals and birds will be affected.
  • Rising sea level will lead to the displacements of people. It could create 187 million climate refugees by 2100, according to a study.

 

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What are the two primary factors of sea-level rise?

The rise in sea-levels is linked to two primary factors, both induced by global warming.

Thermal expansion:

The oceans are absorbing more than 90% of the increased atmospheric heat associated with greenhouse gas emissions. When water heats up, it expands. The ocean water expands to fill a greater volume and takes up more space. This is called thermal expansion, and it is responsible for one-third of the sea-level rise, according to studies.

Melting of glaciers and ice caps:

Warmer temperatures cause land-based ice such as glaciers and ice sheets to melt, and the meltwater flows into the ocean to increase sea level. Melting ice causes about two-thirds of the rise in sea level.

If all the ice in glaciers and sheets melt then the sea level would rise by 216 feet. That could cause some countries to disappear under the oceans. That’s a scenario scientists think would probably take many centuries, but it could eventually happen if the world keeps burning fossil fuels indiscriminately.

 

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