The cultivation of rice, a staple in the Indian diet, is increasingly being affected by environmental concerns such as water scarcity, climate change, global warming and pollution, worry experts
Surrounded by the river Ganges in the north and river Sone in the east, Bhojpur is one of the most fertile lands for rice cultivation in Bihar. With time, however, the area under rice cultivation is shrinking in the district.
According to Dr Pravin Kumar Dwivedi, senior scientist and head at Krishi Vigyan Kendra Bhojpur, more than 5 lakh hectares of land in the district is under rice cultivation, while around 40,000 ha of land has no rice, which was not the case in 2017-18, he said.
The district is completely dependent on the Sone canal for cultivation, but because of irregular rainfall, the canal’s catchment area dries up, resulting in major losses, Dwivedi told CarbonCopy. “If the canal fails, the rice nursery also fails,” he said.
Not just Bhojpur, rice cultivation in many other districts of India have been affected by various environmental concerns such as water scarcity, climate change, global warming and pollution.
With India poised to become the world’s most populous country by 2050, per capita land availability, which was around 0.32 ha in 2001, is estimated to decrease to 0.23 ha and 0.19 ha in 2025 and 2050 respectively, putting more stress on agriculture. The World Bank estimates that India’s per capita arable land has declined by almost two-thirds from 0.339 ha in 1961 to 0.116 ha in 2018.
Bumper food grain production
While India’s net sown area has remained fairly constant at around 141 million ha over the past few decades, India’s foodgrain production has been hitting the record books every few years. Production is set to hit a record 303.34 million tonnes (MT) in 2020-21, according to the second advance estimates— higher than what was achieved during 2019-20 (297.50 MT) by 5.84 MT. A similar trend has been seen five times in the past 10 years.
Amongst the major crops, the total production of rice during 2020-2021 is estimated to be 120.32 MT, 1.45 MT higher than the previous year. For rice, too, production numbers have consistently been rising since 2016-2017. According to official estimates, current rice production is 12.23 MT higher than the past 10 years’ average production of 108.09 MT.
But is it rising fast enough to meet future demands?
Over thousands of years, rice has had a staple and stable presence at every Indian dinner table, transcending barriers of caste, class, language and religion. One of the primary reasons why it has managed to do so is its ability to grow in the hills as well as coasts. It has left an indelible mark on the country’s social framework. There are festivals dedicated to its harvest and it is also used religiously for rituals and ceremonies. It also finds a mention in ancient texts such as the Yajur Veda. It’s abundance, therefore, is often taken for granted.
With a growing population, the demand for rice has been increasing but is production rising fast enough in India to meet future demands?
Between 1990-91 and 2017-18, the area, production and productivity of rice in India have increased at the rate of 0.09 mha, 1.45 MT and 1.36 q/ha per year, respectively. However, state-level analysis of the parameters for the same period depicts a negative trend in rice growth in 45% of the states.
According to a report by PRS, although India is the second-largest producer of rice in the world, its yield is lower than China, Brazil and the USA. Additionally, India’s productivity is also growing at a slower pace as compared to other countries like Brazil and China.
Despite coming a long way in terms of increasing production, the challenge of meeting future demand is considerable. The projected demand for rice by 2050 is estimated to be 197.40 MT for a population of 1.65 billion— almost 80% higher than the current demand.
The total rice cultivated area in India is divided into four distinct zones – very suitable, suitable, moderately suitable and unsuitable. Currently, India produces 74.68 MT of kharif rice in suitable areas. The report noted that a 30% increase in production in suitable areas (97.08 MT) will be required to meet the demand for rice by 2030. However, to meet the demand by 2050 (197.40 MT), the rate has to be increased by more than 30%.
According to Dr A Amarender Reddy, principal scientist at ICAR-Centre Research Institute for Dryland Agriculture, as of today, India is sufficiently producing paddy considering that it is also exporting it to other countries. “But it is a cyclical pattern. In 10 years, there will be a surplus and in the next 10 years there might be a shortage,” he explained.
In the next 10-20 years, paddy production has to cope with the rising population and it also has to sustain its export to other countries. “We have to constantly increase our paddy production to meet both these demands,” he stressed.
Response of rice yield to elevated CO2 and temperature
While rice responds positively to elevated CO2 through photosynthesis, associated events like rising temperatures, changing patterns of precipitation and increased frequency of droughts and floods will result in yield reduction and production risks.
Even with CO2 there is a threshold. According to Dwivedi, if CO2 is increased beyond the threshold level, it will be decremental for plant growth and will have a negative effect on photosynthesis.
The maturity period of the rice crop will reduce, This will lead to a reduction in the leaf area followed by less chlorophyll production. Ultimately, it will decrease photosynthesis, which will result in low yield, he explained.
A similar result was found in a study conducted recently. It revealed that rice yield will increase in the period 2020-2029 because it will be influenced by an increase in precipitation and CO2 concentration. But it will decrease during the 2050s when change in temperature will have more influence on rice growth.
“During the 2050s, CO2 will increase, but the temperature will increase in an even larger proportion. After reaching a certain threshold (520 ppm), CO2 will not increase rice yield,” said Jha, co-author of the study.
High temperature causes thermal stress in rice plants, affecting physiology, metabolic and enzymatic activities. It has been reported to cause decreased and delayed emergence, poor seedling growth, decreased number of pollens and shedding of pollens.
“This sterility in rice plants, in turn, reduces the rice productivity because of low grain filling,” said Gurdeep Singh Malhi, an agricultural researcher at Punjab Agricultural University.
Moreover, warm and humid conditions due to climate change make rice plants very vulnerable to pests, diseases and weeds, he adds.
With a per degree Celsius increase in temperature, there will be a decrease in rice yield in subtropical regions, according to another study that analyses the effect of climate change on rice yield in Kharagpur.
It also pointed out that the rice yield will increase with a per mm increase in rainfall (0.35 kg/ha). However, decrease in the yield due to rise in temperature will be 156.2 kg/ha, which is 446 times more than the former, suggesting that high temperature will have more influence on the yield.
Water trends in India and how it will affect rice yield
A more immediate concern, which complicates the climate question infinitely, is an impending shortage of water in the country. According to a NITI Aayog report, 600 million Indians face high to extreme water stress. By 2030, the country’s water demand is projected to be twice the available supply, implying severe water scarcity for hundreds of millions of people and an eventual ~6% loss in the country’s GDP.
It doesn’t help matters that water is the primary factor that determines the success of rice crops. Most Indian farmers require a lot of water as they grow long-term rice and medium-term rice that have cropping cycles of 150 days and 135 days respectively, said Dwivedi.
With the introduction of hybrid rice, “a good number” of areas have come under it, but the duration is the same as of medium-term rice, he said. Even the water requirement for both types of rice is almost the same, he adds.
“We are not irrigating, but flooding the field so the quantum of irrigation will be the same in both varieties.” However, productivity will be more in hybrid varieties, he added.
Most rice growers use excessive water because it is available at cheap rates, said Reddy. He added that through canal irrigation, farmers cultivate paddy even in dry areas, which are poorly suited for rice.
“It is an unsustainable practice and we have to restrict paddy cultivation to areas where natural water is in excess like Assam, Odisha, West Bengal, Uttar Pradesh, Bihar.”
A management problem?
A recent study estimates that under current practices adopted by farmers in India, rice yields will see a substantial decline by 2050 unless suitable management strategies are employed to mitigate the effects of climate change. Unless conservation practices are combined with a reduction in post-harvest losses, the study warns, irrigation requirements for higher yields could surge by up to an untenable 45%.
“Under the current farming method, 1 ha area of rice uses 15,000 to 18,000-metre cube water out of which 50%-80% is lost due to percolation loss and leaching loss that affect rice yield and development,” said Dr Ranjeet Kumar Jha, assistant professor at KL University, Vijayawada and co-author of the study.
While the environment plays a significant role in rice production, development of new rice varieties is also the need of the hour.
‘Sahabhagi’ is one such genetically modified, drought-tolerant paddy seed that is being developed by Central Rice Research Institute, Dwivedi said. The seed can survive and produce crops even without water for over three weeks thereby reducing emissions.
According to Dwivedi, “Everything you can manage, but you cannot manage the genetic makeup. It affects the productivity of the crop either in a good or a bad way,”
To reduce methane and nitrous emissions, he suggests alternate wetting and drying (AWD) of rice fields, which reduces the decomposition of fertilisers and crop residues in flooded rice – the major source of the methane emissions in rice cultivation.
AWD is an irrigation practice in which periodic drying and re-flooding irrigation scheduling is done. The fields are allowed to dry for a few days before re-irrigation, without putting stress on the plants.
“Variety suitable for AWD is a priority right now and scientists are working on it,” he added.
The senior scientist is also working with mineral Boron to minimize crop stress.
“We have done a lot of trials of Boron on wheat and found that it is effective in reducing stress in the crop due to rise in temperature,” he explained, adding “Rise in temperature leads to desiccation of pollen and reduced productivity.”
According to Jha, a combination of conservation strategies and a 30% reduction in post-harvest losses is required to achieve a 60% increase in rice production.
He explains that if farmers switch to direct-seeded plants rather than transplants, they can increase production with less water demand. Traditional rice farming methods involve flooding the fields with water as rice transplants require about six inches of standing water.
Jha’s paper also advocates keeping the crop residue on the ground to prevent soil surface from continuously losing water due to temperature, humidity and wind. Moreover, once the crop residue decomposes, it will increase the soil quality.
According to Reddy, with the development of more irrigation canals and better infrastructure, the impact of climate change on paddy yields can be mitigated. He also advocated crop diversification – replacing paddy with pulses, oilseeds where water is not available for easy cultivation.
A recent initiative of Climate Smart Agriculture has also started all over the world, which aims to sustain crop production even in adverse climate conditions. It is a holistic approach and includes all the technological, agronomical and breeding initiatives in a combined approach to make the production of crops more suited to the changing climatic conditions.
Despite increasing foodgrain production in the country, India still has high levels of food insecurity. According to the Global Hunger Index of 2020, India ranks 94 out of 107 countries.
The Food and Agriculture Organization (FAO) estimated that the world population is going to reach 9.15 billion by 2050 and to fulfil the food demand, agriculture production needs to increase by 60%. For India, future food security may rest on the urgent attention to manage its rice productivity problem.