Tuesday March 19, 2019

‘Water management in Rice output key to tackle climate change’

"Improvement in water management will also help in reducing methane emissions and arsenic uptake in the rice fields"

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Rice Crop at it's ripen stage Image Source: Wikimedia Commons
  • Improvement in water management will also help in reducing methane emissions and arsenic uptake in the rice fields
  • De-watering is the practice of removing water from the rice paddies, at least once during the season
  • “Adopting some form of aerobic rice production will also reduce the release of arsenic from soils to groundwater, and the subsequent uptake of arsenic by rice plants.”

At a time when climate change is set to impact rice production in Asia, simple water management by farmers as an adaptation strategy will minimise the damage, an expert said.

“Climate change will impact rice production in large parts of Asia, including India. Water management will be a key feature of decisions aimed at adapting to the impacts of climate change,” Dennis Wichelns, Senior Research Fellow of Thailand-based Stockholm Environment Institute (SEI), said during the Knowledge Forum on Climate Resilient Development in Himalayan and Downstream Regions held in New Delhi recently.

The event was organised jointly by the Ministry of Agriculture and Farmers Welfare, Kathmandu-based International Centre for Integrated Mountain Development (ICIMOD) and Delhi-based IEG.

According to Wichelns, improvement in water management will help in areas where higher temperatures are likely and where shift in rainfall pattern is expected.

In certain areas, crop yields will increase in some seasons, perhaps in response to higher rainfall during the production cycle or with a reduction in summer days in the northern regions. In other areas, yields might be reduced due to higher night temperatures, untimely drought conditions, or submergence caused by massive natural events.

According to Wichelns, improvement in water management will also help in reducing methane emissions and arsenic uptake in the rice fields.

“Methane is a potent greenhouse gas. It is estimated that up to 20 per cent of the anthropogenic releases of methane to the atmosphere are generated in agriculture, largely by livestock and in rice production,” he said.

Paddy field in Japan Image Source: Wikimedia Commons
Paddy field in Japan Image Source: Wikimedia Commons

“The anaerobic conditions in which paddy rice is produced is largely responsible for the methane generation and release. Methanogenic organisms, which thrive in anaerobic conditions, break down carbonaceous materials and form methane,” he added.

Efforts to reduce methane generation and release in rice production can substantially reduce greenhouse gas emission from agriculture, thus contributing to climate change mitigation,” Wichelns said.

He said rice production generates substantial amount of methane annually, thus adding notably to the amount of greenhouse gases released into the atmosphere each year.

Switching from flooded paddy production to aerobic rice production or to alternative crops that are produced in aerobic conditions can substantially reduce regional methane emissions, Wichelns added.

Nitrous oxide emissions can increase when switching from anaerobic to aerobic production, yet the change in production methods will reduce global warming potential.

“Adopting some form of aerobic rice production will also reduce the release of arsenic from soils to groundwater, and the subsequent uptake of arsenic by rice plants.” Wichelns said.

Arsenic accumulation in rice grain declines sharply when farmers switch from anaerobic to aerobic production methods. Millions of residents of South and Southeast Asia already are exposed to harmful concentrations of arsenic in drinking water. In those areas, and elsewhere, successful efforts to reduce arsenic uptake in rice will be helpful in reducing total exposure, to the benefit of many adults and children who currently consume harmful amounts of arsenic each day, he said.

De-watering is the practice of removing water from the rice paddies, at least once during the season. Normally, paddies are kept flooded for the entire season, from planting to about two weeks ahead of harvest. Substantial methane is generated and released during that time.

“If farmers remove the water for seven to 10 days mid-season, they can substantially reduce methane generation and release. The paddies are re-watered after the de-watering, but the methanogenic organisms will have been greatly reduced during those seven to 10 days,” Wichelns stressed.

The practice allows oxygen to reach the root zone. The oxygen is unfavourable to the methanogenic organisms, yet favourable to rice roots and thus rice productivity. Therefore, the de-watering also contributes to producing more resilient rice plants with stronger root systems, he added.

Much of the rice production in South and Southeast Asia is found in the deltas formed by major rivers, such as the Mekong, Irrawaddy, and Ganges-Brahmaputra. Rice is well-adapted to these deltaic regions, many of which are characterised by monsoonal climates.

“Given the important role of rice production in rural economies across much of Asia, adaptation strategies are needed urgently to ensure that smallholder farmers can continue producing rice for domestic and international markets, while generating sufficient income and ensuring that household and national food security goals are achieved.” he said. (Source: IANS)

(Imran Khan can be contacted at imran.k@ians.in)

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    Such methods to reduce methane emissions must be made aware to the farmers. If it is followed in the entire country, the green-house gas emissions can be reduced.

  • Vrushali Mahajan

    Farmers should be informed about the various ways in which water management can be done in their farms. This can help many people retaining water and use it for other purposes.

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  • AJ Krish

    Such methods to reduce methane emissions must be made aware to the farmers. If it is followed in the entire country, the green-house gas emissions can be reduced.

  • Vrushali Mahajan

    Farmers should be informed about the various ways in which water management can be done in their farms. This can help many people retaining water and use it for other purposes.

Next Story

Eye In The Sky: Space Technology Aiding Meghalaya To Expand Boro Rice Cultivation

The data tells us that slope, soil texture, soil fertility (acidity) and soil drainage are the major limiting factors/problems, because of which maximum areas are found marginally and moderately suitable for boro rice expansion.

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Meghalayas tough hill terrains that limit field visits, space technology is aiding the selection of areas that are suited for growing and expanding cultivation of boro rice

In Meghalayas tough hill terrains that limit field visits, space technology is aiding the selection of areas that are suited for growing and expanding cultivation of boro rice which is sown in winter and harvested in spring/summer, officials said.

Boro refers to a special type of rice cultivation on residual or stored water in low-lying areas after the harvest of kharif (winter) rice. Space technology has zoomed in on potential stretches in the state and offered a bird’s eye view of tracts that are best suited for growing boro season rice.

This will help bridge the demand-supply gap in Meghalaya, where 81 percent of the population is dependent on agriculture but the net cropped area is proportionately quite less: only about 10 percent of the total geographical area of the state.

So, to identify areas for expansion of boro rice in Meghalaya, the North Eastern Space Applications Centre (NESAC) at the request of the Meghalaya’s Directorate of Agriculture, tapped into a suite of geospatial technologies.

Eye in the sky: Space technology aiding Meghalaya to expand boro rice cultivation

These technologies such as remote sensing and Geographic Information Systems are a range of modern tools contributing to the geographic mapping and analysis of a range of data about people, such as population, income, or education level and also about landscapes.

The move to expand area of rice grown in the boro season comes under the Meghalaya State Rice Mission (MSRM) aimed at narrowing the gap between rice production and consumption by doubling the production of rice – a major staple food of the northeastern state, accounting for over 80 percent of the foodgrain production.

In West Bengal and Bangladesh, expansion of irrigation, essential for supporting the boro rice production, led to a rapid increase in boro rice area and production during the past two decades and Meghalaya can benefit by deploying a similar strategy of expanding the boro season area, the state agriculture department opined.

Previous estimates from the rice mission document peg the consumption at approximately 400,000 tonnes annually during the years 2010-11. This estimate is double the rice produced during that period.

“Rice recorded an annual production of 3,01,076 metric tonnes during the year 2015-16 at an average productivity of 2.72 metric tonnes per hectare. Our spring rice/boro paddy produces an average yield of 4.28 metric tonnes per hectare under assured irrigation,” the agriculture department said.

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Mature rice fields of, IR8 and DGWG varieties. VOA

In Meghalaya, the rice crop is distributed in three rice ecosystems. They are low- altitude rice that covers 70 percent of total rice growing areas, mid-altitude rice covers 25 percent and high altitude rice that covers five percent.

In a report submitted to NITI Aayog, the Meghalaya government has said that the under-utilisation of land during the winter season has resulted in shortage of rice for the ever-increasing population.

In addition, with assured irrigation, boro paddy yield is double the average yield per hectare compared to sali rice.

“Boro paddy gives an average yield of 4 MT per hectare compared to the average yield of 2 MT per hectare of sali paddy,” according to the report.

Further, winter planting is free from flash floods and is well-suited for SRI (System of Rice Intensification) technique with yields of 6-7 MT per hectare, the report said, justifying the augmentation of boro paddy cultivation in areas where this practice was not in vogue.

With the NESAC data at its disposal, the department of agriculture has initiated steps for application of the findings by taking a policy decision to link the activity for growing boro rice with the Indian government’s National Rural Employment Guarantee (NREGA) program.

“This will achieve both the objective of providing assured employment under NREGA and also productive output and income for the NREGA wage earner cum farmer,” an agriculture department official said.

Space tech can reduce time lost on trial and error

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Rice cultivation requires extensive labor. Source: Pixabay

“By using satellite images and data with ground information on parameters such as slope, soil and climate, we mapped potential areas for expansion of boro rice cultivation. This was one of the first of its kind project in the northeast,” Pratibha T. Das of NESAC told Mongabay-India.

Having space technology focus on potential areas saves time and money in implementation by skipping the field trial stage, explained Das.

In an email communique to Mongabay-India, officials at Meghalaya’s agriculture department also reiterated that this approach eliminates the trial and error method “saving time, effort and money and scale of implementation in a given (short) period of time.”

Das further said: “Even though the identified areas are small, the agriculture department need not conduct field trials; they can directly select the potential areas from the maps and start cultivation.”

The mapping exercise covered landscapes spread across nearly 5000 square km at elevation below 200 metres and excluding forest, built up and barren rocky areas. The findings published in Current Science show that out of 4903 sq. km study area only 807 sq. km (16.5 percent) is suitable for boro rice cultivation.

Though 16.5 percent area is suitable for boro rice, only 0.8 percent (6.35 sq. km) area is highly suitable, which is found in West Garo hills district. Around 581.74 sq. km is marginally suitable whereas 219.07 sq. km area is moderately suitable.

“The data tells us that slope, soil texture, soil fertility (acidity) and soil drainage are the major limiting factors/problems, because of which maximum areas are found marginally and moderately suitable for boro rice expansion,” said Das.

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Based on problems/limitations of the land, land users and planners can decide on crop management strategies to increase productivity, she said.

Thematic maps like soil drainage, soil texture, soil depth, flooding and gravel/stoniness and land use maps were dovetailed with soil sample analyses and digital elevation models to get a clear picture on ground.

Soil samples were collected from 121 locations and analysed, revealing that sandy clay soil texture, that was best fit for boro rice, was distributed in six percent of the area examined. (IANS)

(In arrangement with Mongabay.com, a source for environmental news reporting and analysis. The views expressed in the article are those of Mongabay.com. )