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Climate Change and Sustainability
Rice production is both a victim and a contributor to climate change.
Drought, flood, saltwater, and extreme temperatures devastate crops and risk the livelihoods of 144 million smallholder rice farmers each growing season.
At the same time, traditional cultivation methods, such as flooding paddy fields and burning rice straw in open fields, contribute approximately 10% of global man-made methane, a potent greenhouse gas.
At IRRI we develop and adapt climate-responsive solutions, working with extension agents, national research institutions, and governments across South Asia, Southeast Asia, and Africa to promote sustainable rice-based food systems.
Drought is one of the most widespread and damaging of all environmental stresses, affecting 23 million hectares of rainfed rice in South and Southeast Asia alone. Rice is normally grown during periods of high rainfall, the time of year commonly referred to as the rainy season. However, rice is often subjected to periods of severe moisture stress because of the marked variation in time and intensity of rainfall in India. Thus the ability of the crop to withstand drought is essential in most tropical rice-growing areas.
In a recent farmers’ sensitization program jointly organized by IRRI and the Zonal Drought Resistance Paddy Research Station (ZDRPRS) in Purulia district of West Bengal in Eastern India, ZDRPRS informed farmers of the newly available Drought Tolerant Rice Varieties (DTRVs). The program entitled ‘‘Enhancing Productivity through DTRVs with Improved Crop and Weed Management Options in Rice-based Cropping Systems’ organized in the last week of January 2020 elaborated on relevant crop management practices like crop establishment, seed priming, water management, nursery and main field management, and weed management; and discussed possibilities for post-rice cropping in rainfed and undulated uplands.
In spite of getting an average annual rainfall of 1100 mm, Purulia has a cropping intensity of 110 percent, which is the lowest in the state of West Bengal. In the wet season, Purulia receives more than average rain, but due to the undulated land type, this rainwater does not get uniformly used-up. In this scenario, short-duration DTRVs are a blessing for poor marginal farmers for harnessing the full productivity potential.
Although drought-resistant rice varieties are needed most by dryland rice farmers, the ‘drought-resistance’ characteristic is very important also for rainfed wetland rice, as rice yields from rainfed areas are limited by unseasonal drought. Due to less initial rains, farmers fail to accumulate enough water in the fields early in the season, to prepare the lands and ready them for transplanting. Resultantly, large areas in shallow rainfed ecosystems are left untransplanted in the years with less initial rainfall.
Speaking at the farmers’ sensitization program in Purulia, with over 70 progressive farmers and senior officials from the state and district agricultural department attending, Mr. M.C. Dhara, Joint Director Agriculture (Rice Division), Purulia districts, emphasized on the importance of DTRVs in raising productivity of rainfed upland environments and shared experiences of farmers benefiting from modern management practices with DTRVs and traditional rice varieties.
“The emergence of hi-tech and precision agriculture technologies that are available at subsidized prices to cultivate vegetables, oilseeds, and pulses means that even after the wet season, the fields can be optimally utilized for other crops. Sowing time and the proper pairing of post-wet season crops can further enhance productivity. Several technology interventions are already being made to complement the Central Government’s ‘Doubling the Farmers’ Income’ program,” he said.
During the interactive session, speaking on improved rice varieties and the latest farming technologies, Dr. Ashish Kumar Srivastava, from IRRI SARC also provided an overview of agronomic management practices for the newly-released DTRVs.
“Matching management practices can produce 0.5 to 1.0 t/ha additional yield of DTRVs when they are cultivated by using the right crop management practices”, he said.
Dr. Bhowmick, Assistant Agronomist at Rice Research Station (Chinsurah, West Bengal) and Mr. Anadi Bhanja, Assistant Director of Agriculture (Farm) for Purulia district, commented on the many ways in which the West Bengal Government is working with the Government of India, in close association with IRRI, for undertaking initiatives to improve productivity potential of rain-deficit areas.
“Short duration crops need less water for cultivation and can withstand short to medium spells of soil water scarcity. Utera or Paira cropping systems are important in this case to maximize use of residual moisture for germination of rabi crops, like chickpea, linseed, lentil, and lathyrus,” Dr. Bhowmick said.
IRRI has developed and released several drought-tolerant rice varieties like Sahbhagi dhan, and DRR dhan 42, 43 and 44 in India, wherein field trials suggest that the average yield advantage of drought-tolerant varieties over drought-susceptible ones is 1.0–1.5 tons per hectare under drought conditions. Disseminating seeds of stress-tolerant rice varieties, focusing on women farmers’ empowerment and ensuring gender equity in rice farming, are some of the key initiatives in the area, through which hundreds of progressive farmers have already benefited.
Rice farmers in Southeast Asia are hesitant to adopt the water-saving technology, alternate wetting and drying (AWD) for fear the practice will lead to increased rodent pest damage. A new study has shown that AWD does not affect how much rodent pests damage a standing rice crop.
AWD is one of the most widely disseminated water-saving technologies developed by the International Rice Research Institute (IRRI) in collaboration with many partner organizations. The simple but effective irrigation scheduling technique reduces the water inputs in rice production by 20−25%. The water saved through the use of AWD and modern rice varieties has enabled farmers to plant a third nonrice crop in between two rice crops, thereby increasing the intensification of the rice-based system and the farmers’ income.
AWD also reduces the emission of methane, a greenhouse gas, from rice fields by as much as 50%.
Despite numerous advantages to adopting AWD to manage water use in rice fields, many farmers in Southeast Asia are hesitant to use it because they fear it will lead to increased rodent pest infestation and higher yield loss..
Genuine anxiety
The farmer’s concern over rodent pest damage is not unfounded. Rodents have an enormous economic impact on the growing rice crop and stored grain in developing countries. Rats need to eat 10–15% of their body weight each day and, in grain storage, they contaminate much more rice than that with their droppings. In one year, 25 adult rats would eat and damage about half a ton of grain and produce about 375,000 droppings.
“Rodents are major pests in agricultural production,” said Dr. Grant Singleton, a rodent expert at IRRI. “In Asia, rodents cause, on average, annual preharvest losses of 5–10% in rice crops. Post-harvest losses are at a similar level. A loss of 6% is substantial, as this is enough rice to feed 225 million people for a year.”
Unfounded fear
Renee Lorica, former University of Greenwich scholar at IRRI investigated the effects of AWD on the fluctuation of rodent pest numbers, their breeding patterns, how they use the rice field landscape, and the damage levels they inflict on growing rice crops. Her study focused on the rice field rat (Rattus argentiventer) and the oriental house rat (R. tanezumi,). These are the most important rodent pests of rice in Indonesia and the Philippines, respectively.
“We found that both species predominantly used the rice paddies regardless of water level,” Dr. Lorica said. “This means that they don’t really prefer dry field over flooded ones as the farmers feared. We think that fear of predators, not water levels, is the primary factor driving habitat use. The breeding of the rice field rat is dictated by the crop stage of rice while the availability of food influences the breeding of the oriental house rat.
“We recommend the continued promotion of AWD as an integral part of the climate-smart technology package for rice production in Asia and Africa,” she added. “There is no cause for farmers to worry that AWD will aggravate rodent pest activity in rice.”
In supporting Vietnam to achieve its Nationally Determined Contributions (NDC) under the Paris Agreement, the International Rice Research Institute (IRRI) worked together with the Institute of Policy and Strategy for Agricultural and Rural Development (IPSARD) to develop a toolkit. This is comprised of three stand-alone tools: “MapAWD,” used for targeting and mapping suitable areas; “SECTOR,” used for calculating greenhouse gas (GHG) emissions under different project scenarios; and “Rice-CBA,” used for assessing the costs and benefits of these scenarios to guide planning of mitigation options in rice production.
Dr. Tran Cong Thang, Director General of IPSARD, highlighted the usefulness of such tools in advancing Vietnam’s national strategy of transforming the rice sector towards sustainable production and reduction of environmental impacts. In such processes, the Ministry of Agriculture and Rural Development (MARD) highlights the importance of evaluating mitigation measures both for effectiveness and efficiency. However, the procedures to establish hotspots for mitigation investment potential require specialized knowledge and are often too general to be useful in a regional context. Recognizing this gap, a customized, dynamic, and user-friendly approach was requested to be developed. The technical components of the toolkit were jointly developed by IRRI and UNIQUE in consultation with IPSARD to ensure regional and national relevance. This project is supported by the Climate Technology Centre & Network (CTCN).
On 10 November 2020, IRRI and IPSARD organized a regional training workshop titled “Toolkit for cost-benefit analysis of mitigation options in rice production in Vietnam” to introduce the three tools that support planning and decision-making of mitigation projects in rice farming. The event was conducted both in-person and online simultaneously to accommodate a large number of participants (73) and also to extend the reach to participants all over the country. Participants were from MARD, government research institutes, NGOs, private industries, and universities from different areas of Vietnam.
The three tools were introduced with step-by-step instructions for installation, data input, model running, and result interpretation. The training included a demonstration of how to link the tools together in project planning with two comparative use case scenarios. Feedback from one participant mentioned that “the presentations and instructions were clear and specific; I was able to follow despite attending online. Myself and other colleagues in the Centre for Climate Change Study in Central Vietnam expect more in-depth training workshops for these tools”. Many others appreciated the usefulness of these tools and contributed suggestions for the practical application of the tools in various production contexts.
A second hands-on training will be conducted early December wherein participants will be guided through the process of calculating GHG emissions under multiple improved crop management production scenarios and of performing cost-benefit analysis using realistic use-case examples. After both training workshops, participants will be able to use and adjust input data and models of the tools to develop project plans which optimize environmental and economic benefits.