A recent study by Harvard University, the Jet Propulsion Laboratory, Environmental Defense Fund (EDF), the University of Michigan, the Public Health Foundation of India, the International Maize and Wheat Improvement Center (CIMMYT), Columbia University, and the University of California, Los Angeles, has determined the environmental impact of a government policy of delayed rice planting in northwest India.
âWe have shown that the groundwater and air quality crises are major regional issues and are interconnected,â said co-author Balwinder-Singh, former Cropping System Scientist at the International Maize and Wheat Improvement Center (CIMMYT) in New Delhi. âBut there is still a path to clearer skies and safer water practices. Local solutions include planting rice varieties that either grow more quickly or need less water. Promoting less water-demanding crops like maize would be helpful in zones with severe groundwater depletion.â
A recent study of the groundwater in India revealed that, by 2025, large areas of the north-western and southern parts of the country will have âcritically low groundwater availabilityâ, leading to a decrease in cropping that will ultimately cause an imbalance in the food security for millions.
Groundwater is essential for Indian agriculture and rural livelihoods, but groundwater levels are declining. Simply providing canal irrigation as a substitute irrigation source will likely not be enough to maintain current production levels.
Water pumped from a deep irrigation well, called a tube well, at a wheat farm in west India’s Gujarat state. (Photo: Meha Jain)
India is the world’s second-largest producer of wheat and rice and is home to more than 600 million farmers. The country has achieved impressive food-production gains since the 1960s, due in part to an increased reliance on irrigation wells, which allowed Indian farmers to expand production into the mostly dry winter and summer seasons.
But those gains have come at a cost: The country that produces 10% of the world’s crops is now the world’s largest consumer of groundwater, and aquifers are rapidly becoming depleted across much of India. Indian government officials have suggested that switching from groundwater-depleting wells to irrigation canals, which divert surface water from lakes and rivers, is one way to overcome projected shortfalls.
The authors estimate that if Indian farmers lose all access to groundwater in overexploited regions, and if that irrigation water is not replaced with water from other sources, then winter cropped acreage could be reduced by up to 20% nationwide. However, that scenario seems highly unlikely and was included in the study only as an upper-bound estimate.
It seems more likely that any future groundwater shortfalls would be at least partially offset by increases in canal irrigation. But even if all Indian regions currently using depleted groundwater switch to canal irrigation, winter cropped acreage could still decline by 7% nationwide and by 24% in the most severely affected locations, according to the researchers.
Water alternatives needed
âOur results highlight the critical importance of groundwater for Indian agriculture and rural livelihoods, and we were able to show that simply providing canal irrigation as a substitute irrigation source will likely not be enough to maintain current production levels in the face of groundwater depletion,â said study lead author Meha Jain, an assistant professor at the University of Michiganâs School for Environment and Sustainability.
âWe need coordinated efforts to solve this water availability and food security issue, which should be supported by science-led policy decisions on what strategies and technology solutions to scale out to improve irrigation efficiency,â said co-author Balwinder Singh, a Cropping Systems Simulation Modeler at the International Maize and Wheat Improvement Center (CIMMYT).
The study analyzed high-resolution satellite imagery and village-level census data and focused on winter cropped acreage. While nearly all Indian farmers plant crops during the monsoon to take advantage of seasonal rains, winter agriculture is mainly reliant on groundwater irrigation and now accounts for 44% of the country’s annual cropped acreage for food grains.
“These findings suggest that other adaptation strategies, in addition to canal expansion, are needed to cope with ongoing groundwater losses,” Jain said.
The possibilities include switching from winter rice to less water-intensive cereals, increased adoption of sprinklers and drip irrigation to conserve water in the fields, and policies to increase the efficiency of irrigation canals.
While groundwater depletion is becoming a global threat to food security, and the extent of current and projected groundwater depletion are well documented, the potential impacts on food production remain poorly quantified. The study is the first to use high-resolution empirical data, including census data about the irrigation methods used in more than 500,000 Indian villages, to estimate the crop production losses that may occur when overexploited groundwater is lost.
“Understanding the complex relationship between food security and water availability is crucial as we prepare for future rainfall variability due to global climate change,” said co-author Gillian Galford of the University of Vermont.
The proliferation of deep (>30 meters) irrigation wells called tube wells since the 1960s has enabled Indian farmers to increase the number of seasons when crops are planted in a given year. This increase in “cropping intensity” is credited for much of the country’s food-production gains.
Maps showing state-by-state Indian winter cropped area loss estimates due to groundwater depletion in coming decades, with and without replacement by canals. Darker shades of pink and red indicate greater projected losses. The map on the left (A) shows projected winter cropped acreage losses if all critically depleted groundwater is lost, with no replacement. The map on the right (B) shows projected winter cropped acreage losses if groundwater irrigation is replaced with canals, using national-level regression coefficients. (Graph: Jain et al. in Science Advances 2021)
Big data for food security
The researchers used satellite data to measure Indian winter cropped area, a key determinant of cropping intensity. They then linked the satellite data to census information about the three main types of irrigation infrastructure in India: shallow “dug wells,” deeper tube wells and canals that divert surface water.
Linking the two datasets allowed them to determine the relative efficacy of each irrigation method. That, in turn, enabled them to estimate potential future acreage losses and the ability of canal expansion to fill the gap.
The study’s worst-case scenario found that winter cropped area could decrease by up to 20% nationwide and by 68% in the most severely affected regions, if farmers lose all access to groundwater and if that irrigation water is not replaced from another source. The expected losses would largely occur in northwest and central India, according to the study.
The researchers also found that increased distance from existing irrigation canals is strongly associated with decreased acreage planted with winter crops. In the future, a greater reliance on canals could increase inequities related to irrigation access, according to the authors.
“This suggests that while canals may be a viable form of irrigation for those who live near canals, they may lead to more unequal access to irrigation across villages compared to wells, with negative impacts for those who live farther from canals,” the authors wrote.
In addition, the lakes and rivers that feed irrigation canals rise and fall in response to rainfall variability, unlike deep groundwater wells. So, a greater reliance on canal irrigation in the future would result in increased sensitivity to year-to-year precipitation fluctuations, as well as any long-term trends due to human-caused climate change.
The authors of the Science Advances study, in addition to Jain and Galford, are Ram Fishman of Tel Aviv University; Pinki Mondal of the University of Delaware; Nishan Bhattarai of the U-M School for Environment and Sustainability; Shahid Naeem, Upmanu Lall and Ruth DeFries of Columbia University; and Balwinder Singh of the International Maize and Wheat Improvement Center (CIMMYT).
The work was funded by a NASA New Investigator Award to Jain and two NASA Land Cover and Land Use Change grants, one awarded to R.S. DeFries and one to Jain.
Fall armyworm is an invasive Lepidopteran pest that favors maize and is native to the Americas. It was identified in Bangladesh for the first time in late 2018 following migration from Africa and southern India.
Supported by the University of Michigan and USAID, this project cooperates with national research and extension partners, CABI and the FAO to strengthen efforts to mitigate impact of the pest on farmersâ income, food security and health.
Objectives
Develop educational materials to help reach audiences with information to improve understanding and management of fall armyworm
Assist the Department of Agricultural Extension (DAE) in deploying awareness raising and training campaigns
Institutional change to improve crop protection and integrated pest management
Prepare the private sector for appropriate fall armyworm response
Support the standing multi-threat pest emergency taskforce
Generate data and evidence to guide integrated fall armyworm management
Hundreds of agricultural professionals in Bangladesh were trained in the latest fall armyworm management strategies as part of a new project that will strengthen efforts against this threat to farmersâ income, food security, and health. The new project, Fighting Back Against Fall Armyworm, is supported by USAID and the University of Michigan.
As part of the project, last November over 450 representatives from government, nonprofits and the private sector participated in three-day training to learn how to identify, monitor and apply integrated pest management approaches.
Fall armyworm presents an important threat to farmersâ income, food security and livelihoods as it continues to spread across the country, in addition to health risks if toxic insecticides are indiscriminately used, said Tim Krupnik, senior scientist and agronomist at the International Maize and Wheat Improvement Center (CIMMYT). It is anticipated the course participants will pass on knowledge about the pest and appropriate control practices to around 30,000 farmers in their respective localities.
âParticipants were selected for their ability to reliably extend the strategies that can be sustainably implemented by maize farmers across the country,â explained Krupnik. âThe immersive training saw participants on their hands and knees learning how to scout, monitor and collect data on fall armyworm,â he said. âThey were also trained in alternatives to toxic chemical pesticides, and how and when to make decisions on biological control with parasitoids, bio-pesticides, and low-toxicity chemical pesticide use.â
Following its ferocious spread across Africa from the Americas, fall armyworm first attacked farms in Bangladesh during the winter 2018-2019 season. Combined with highly apparent damage to leaves, its resilience to most chemical control methods has panicked farmers and led researchers to promote integrated pest management strategies.
In this context, the 22-month Fighting Back Against Fall Armyworm project will build the capacity of the public and private sector for effective fall armyworm mitigation.
The hungry caterpillar feeds on more than 80 plant species, but its preferred host is maize â a crop whose acreage is expanding faster than any other cereal in Bangladesh. The pest presents a peculiar challenge as it can disperse over 200 kilometers during its adult stage, laying thousands of eggs along its way.
Once settled on a plant, larvae burrow inside maize whorls or hide under leaves, where they are partially protected from pesticides. In a bid to limit fall armyworm damage, farmersâ indiscriminate application of highly toxic and inappropriate insecticides can encourage the pest to develop resistance, while also presenting important risks to beneficial insects, farmers, and the environment.
Reaching every corner of the country
Participants of the Fighting Back against Fall Armyworm trainings visit farmersâ fields in Chauadanga, Bangladesh. (Photo: Tim Krupnik/CIMMYT)
As part of the project, CIMMYT researchers supported Bangladeshâs national Fall Armyworm Task Force to develop an online resource to map the spread of fall armyworm. Scientists are working with the Ministry of Agriculture to digitally collect real-time incidents of its spread to build evidence and gain further insight into the pest.
âWorking with farmers and agricultural agencies to collect information on pest population and incidence will assist agricultural development planners, extension agents, and farmers to make informed management decisions,â said Krupnik, who is leading the project.
A key objective is to support national partners to develop educational strategies to facilitate sustainable pest control while also addressing institutional issues needed for efficient response.
âIn particular, the Government of Bangladesh has been extremely responsive about the fall armyworm infestation and outbreak. It developed and distributed two fact sheets â the first of which was done before fall armyworm arrived â in addition to arranging workshops throughout the country. Initiatives have been taken for quick registration of microbial pesticides and seed treatments,â commented Syed Nurul Alam, Entomologist and Senior Consultant with CIMMYT.
âIt is imperative that governmental extension agents are educated on sustainable ways to control the pest. In general, it is important to advise against the indiscriminate use of pesticides without first implementing alternative control measures, as this pest can build a resistance rendering many chemicals poorly effective,â Krupnik pointed out.
To this end, the project also consciously engages members of the private sector â including pesticide and seed companies as well as agricultural dealers â to ensure they are able to best advise farmers on the nature of the pest and suggest sustainable and long-term solutions. To date, the project has advised over 755 agricultural dealers operating in impacted areas of Bangladesh, with another 1,000 being trained in January 2020.
Project researchers are also working alongside the private sector to trial seed treatment and biologically-based methods of pest control. Biocontrol sees researchers identify, release, and manage natural predators and parasitoids to the fall armyworm, while targeted and biologically-based pesticides are significantly less of a health risk for farmers, while also being effective.
The 22-month project, funded by USAID, has 6 key objectives:
Develop educational materials to aid in reaching audiences with information to improve understanding and management of fall armyworm.
Assist the Department of Agricultural Extension in deploying awareness raising and training campaigns.
Prepare the private sector for appropriate fall armyworm response.
Standing task force supported.
Generate data and evidence to guide integrated fall armyworm management.
The Fighting Back Against Fall Armyworm in Bangladesh project is aligned with Michigan State Universityâs Borlaug Higher Education for Agricultural Research and Development (BHEARD) program, which supports the long-term training of agricultural researchers in USAIDâs Feed the Future priority countries.
To achieve synergies and scale, the project will also be supported in part by in-kind staff time and activities, through linkages to the third phase of the USAID-supported Cereal Systems Initiative for South Asia (CSISA), led by the International Maize and Wheat Improvement Centre (CIMMYT). CSISA and CIMMYT staff work very closely with Bangladeshâs Department of Agricultural Extension and the Bangladesh Maize and Wheat Research Institute (BWMRI) in addition to other partners under the Ministry of Agriculture.
A young man uses a precision spreader to distribute fertilizer in a field. (Photo: Mahesh Maske/CIMMYT)
Data from microsatellites can be used to detect and double the impact of sustainable interventions in agriculture at large scales, according to a new study led by the University of Michigan (U-M).
By being able to detect the impact and target interventions to locations where they will lead to the greatest increase of yield gains, satellite data can help increase food production in a low-cost and sustainable way.
According to the team of researchers from U-M, the International Maize and Wheat Improvement Center (CIMMYT), and Stanford and Cornell universities, finding low-cost ways to increase food production is critical, given that feeding a growing population and increasing the yields of crops in a changing climate are some of the greatest challenges of the coming decades.
“Being able to use microsatellite data, to precisely target an intervention to the fields that would benefit the most at large scales will help us increase the efficacy of agricultural interventions,” said lead author Meha Jain, assistant professor at the U-M School for Environment and Sustainability.
Microsatellites are small, inexpensive, low-orbiting satellites that typically weigh 100 kilograms or less.
“About 60-70% of total world food production comes from smallholders, and they have the largest field-level yield gaps,” said Balwinder Singh, senior researcher at the International Maize and Wheat Improvement Center (CIMMYT).
To show that the low-cost microsatellite imagery can quantify and enhance yield gains, the researchers conducted their study in smallholder wheat fields in the Eastern Indo-Gangetic Plains in India.
They ran an experiment on 127 farms using a split-plot design over multiple years. In one half of the field, the farmers applied nitrogen fertilizer using hand broadcasting, the typical fertilizer spreading method in this region. In the other half of the field, the farmers applied fertilizer using a new and low-cost fertilizer spreader.
To measure the impact of the intervention, the researchers then collected the crop-cut measures of yield, where the crop is harvested and weighed in field, often considered the gold standard for measuring crop yields. They also mapped field and regional yields using microsatellite and Landsat satellite data.
They found that without any increase in input, the spreader resulted in 4.5% yield gain across all fields, sites and years, closing about one-third of the existing yield gap. They also found that if they used microsatellite data to target the lowest yielding fields, they were able to double yield gains for the same intervention cost and effort.
“Being able to bring solutions to the farmers that will benefit most from them can greatly increase uptake and impact,” said David Lobell, professor of earth system science at Stanford University. “Too often, we’ve relied on blanket recommendations that only make sense for a small fraction of farmers. Hopefully, this study will generate more interest and investment in matching farmers to technologies that best suit their needs.”
The study also shows that the average profit from the gains was more than the amount of the spreader and 100% of the farmers were willing to pay for the technology again.
Jain said that many researchers are working on finding ways to close yield gaps and increase the production of low-yielding regions.
“A tool like satellite data that is scalable and low-cost and can be applied across regions to map and increase yields of crops at large scale,” she said.
The study is published in the October issue of Nature Sustainability. Other researchers include Amit Srivastava and Shishpal Poonia of the International Maize and Wheat Improvement Center in New Delhi; Preeti Rao and Jennifer Blesh of the U-M School of Environment and Sustainability; Andrew McDonald of Cornell; and George Azzari and David Lobell of Stanford.Â
