Zero till wheat planting in Jaffarabad District.

By Kashif Syed, September 24

More than 70 agricultural professionals met in Islamabad, Pakistan, during September 4-5 to discuss agronomy and wheat activities under the Agricultural Innovation Program (AIP) for Pakistan. The event provided a platform for institutions involved in agronomy and the dissemination of agricultural technology and seed to share advances, discuss issues, and plan future undertakings.

“Crop productivity must be increased through research on innovative crop management techniques, varietal development and dissemination of better techniques and seed to farming communities,” said Dr. Yusuf Zafar, Chairman of PARC, addressing participants and touching upon a key theme of the event. He emphasized that precision agriculture, decision support systems, the use of drones, water productivity improvements and more widespread mechanization were on the horizon for Pakistani farmers, but that this would require active involvement of the public and private sectors.

Developments in zero tillage farming and ridge planting were highlighted in the two-day conference as conservation agriculture practices that are gaining traction in national wheat farming, according to Imtiaz Muhammad, CIMMYT representative and AIP project leader.

“In collaboration with a national network of 23 public and private partners, CIMMYT has reached more than 25,000 farmers through trainings on zero tillage, ridge planting, and direct seeded rice farming,” Imtiaz said, adding that support to farmers included nutrient management education the provision of seed planters. “These techniques are helping farmers to save water, avoid residue burning, and reduce their production costs.”

Collaboration with agricultural machinery manufacturers and other private sector actors is leading to local production of Zero Till Happy Seeders, which sow directly into unplowed fields and the residues of previous crops, according to Imtiaz. “Innovative approaches have also resulted in the production of 1,500 tons of wheat seed in 2018,” he explained.

Wheat seed production and farmers’ replacement of older varieties have progressed through local seed banks established by AIP in partnership with Pakistan’s National Rural Support Program (NRSP). Located in villages, the banks sell quality wheat seed for up to 12 percent less than local markets. “This is critical, because Pakistan’s wheat seed replacement is only 30 percent,” said Imtiaz, adding that there is a 50 percent gap between potential wheat yields and the national average yield for this crop.

The AIP will open more seed banks in remote areas of Pakistan, in conjunction with national partners. As well as producing and processing seed, the banks will provide farm machinery contract services and precision agriculture tools at subsidized rates.

Participants’ recommendations included adding straw spreaders to combine harvesters for rice, to facilitate the direct sowing of wheat after rice. They also suggested that agricultural service providers should help promote the direct seeding of rice and wheat with zero tillage implements. Participants observed that, in Baluchistan Province, support to farmers and service providers could increase the adoption of zero tillage for sowing wheat after rice and of precision land leveling, to improve irrigation efficiency and save water.

The AIP and partners will continue to promote water saving and nutrient management techniques, as well as building the capacity of farmers, national staff and agricultural service providers. Finally, those attending recommended that, for its second phase, AIP focus on the biofortification of wheat and rice, climate smart agriculture, decision support tools, women in farming, knowledge delivery, appropriate mechanization, nutrient management, weed management and water productivity.

AIP is the result of the combined efforts of the Pakistan Agriculture Research Council (PARC), the International Livestock Research Institute (ILRI), the International Center for Agricultural Research in the Dry Areas (ICARDA), the International Rice Research Institute (IRRI), the World Vegetable Center (AVRDC), the University of California at Davis, and the International Maize and Wheat Improvement Center (CIMMYT). It is funded by the United States Agency for International Development (USAID). With these national and international partners on board, AIP continues to improve Pakistan’s agricultural productivity and economy.

The reported work by wheat scientists paves the way for expanded use of wild grass species, such as Aegilops tauschii (also known as goat grass; pictured here) as sources of new genes for higher grain zinc in wheat. (Photo: CIMMYT)

An international team of scientists applied genome-wide association analysis for the first time to study the genetics that underlie grain zinc concentrations in wheat, according to a report published in Nature Scientific Reports on 10 September.

Analyzing zinc concentrations in the grain of 330 bread wheat lines across diverse environments in India and Mexico, the researchers uncovered 39 new molecular markers associated with the trait, as well as 2 wheat genome segments that carry important genes for zinc uptake, translocation, and storage in wheat.

The findings promise greatly to ease development of wheat varieties with enhanced levels of zinc, a critical micronutrient lacking in the diets of many poor who depend on wheat-based food, according to Velu Govindan, wheat breeder at the International Maize and Wheat Improvement Center (CIMMYT) and first author of the new report.

“A collaboration among research centers in India, Australia, the USA and Mexico, this work will expedite breeding for higher zinc through use of ‘hotspot’ genome regions and molecular markers,” said Govindan. “It also advances efforts to make selection for grain zinc a standard feature of CIMMYT wheat breeding. Because varieties derived from CIMMYT breeding are grown on nearly half the world’s wheat lands, ‘mainstreaming’ high zinc in breeding programs could improve the micronutrient nutrition of millions.”

More than 17 percent of humans, largely across Asia and Africa, lack zinc in their diets, a factor responsible for the deaths of more than 400,000 young children each year.

Often used in human disease research, the genome-wide association approach was applied in this study to zero in on genome segments — known as quantitative trait loci (QTLs) — that carry genes of interest for wheat grain zinc content, according to Govindan.

“The advantages of the genome-wide association method over traditional QTL mapping include better coverage of alleles and the ability to include landraces, elite cultivars, and advanced breeding lines in the analysis,” he explained. “Our study fully opens the door for the expanded use of wheat progenitor species as sources of alleles for high grain zinc, and the outcomes helped us to identify other candidate genes from wheat, barley, Brachypodium grasses, and rice.”
Farmers in South Asia are growing six zinc-enhanced wheat varieties developed using CIMMYT breeding lines and released in recent years according to Ravi Singh, head of the CIMMYT Bread Wheat Improvement Program.

Financial support for this study was provided by HarvestPlus (www.HarvestPlus.org), a global alliance of agriculture and nutrition research institutions working to increase the micronutrient density of staple food crops through biofortification. The views expressed do not necessarily reflect those of HarvestPlus. It was also supported by CGIAR Funders, through the Research Program on Wheat and the Research Program on Agriculture for Nutrition and Health. Research partners in India and Pakistan greatly contributed to this study by conducting high-quality field trials.

Turkey – In June, about 50 crop scientists gathered in the wheat fields of Turkey. The group, representing no fewer than 11 countries, offered global technical expertise on and insights into wheat as a crop in drylands. Their goal: learn more about improved winter wheat varieties.

Organized by the International Winter Wheat Improvement Program, or IWWIP, the event – traveling seminar and phenotyping exercise – was a scientific roadshow. The delegation of scientists came from far and near, with 27 from Turkey, and the rest from Azerbaijan, China, Iran, Pakistan, Russia, Turkmenistan, South Korea, Spain, and the United Kingdom.

“This is a unique opportunity to share experiences from East to West and discover the latest findings in genotypes,” says Keser Mesut, ICARDA’s senior scientist and country manager based out of Ankara, Turkey. “Having the opportunity to share wheat improvement activities is extremely important. It helps us understand that our needs are shaped by similar challenges posed by climate change.”

IWWIP is a joint program between the Turkish Ministry of Food, Agriculture, and Livestock, the International Maize and Wheat Improvement Center, widely known as CIMMYT, and ICARDA.

Established in the mid-1980s by Turkey and CIMMYT to breed winter wheat, the IWWIP alliance has expanded over the years with ICARDA joining in 1991. The aim is to develop winter and facultative wheat germplasm for North Africa, Central, and West Asia, and facilitate their exchange.

Click here to read more…

Yellow spores of the fungus Puccinia striiformis f.sp. tritici, which causes stripe rust disease in wheat. Photo: CIMMYT/Mike Listman.

By Mike Listman

Rapidly emerging and evolving races of wheat stem rust and stripe rust disease—the crop’s deadliest scourges worldwide—drove large-scale seed replacement by Ethiopia’s farmers during 2009-14, as the genetic resistance of widely-grown wheat varieties no longer proved effective against the novel pathogen strains, according to a new study by the International Maize and Wheat Improvement Center (CIMMYT).

Based on two surveys conducted by CIMMYT and the Ethiopian Institute of Agricultural Research (EIAR) and involving more than 2,000 Ethiopian wheat farmers, the study shows that farmers need access to a range of genetically diverse wheat varieties whose resistance is based on multiple genes.

After a severe outbreak in 2010-11 of a previously unseen stripe rust strain, 40 percent of the affected farm households quickly replaced popular but susceptible wheat varieties, according to Moti Jaleta, agricultural economist at CIMMYT and co-author of the publication.

“That epidemic hit about 600,000 hectares of wheat—30 percent of Ethiopia’s wheat lands—and farmers said it cut their yields in half,” Jaleta said. “In general, the rapid appearance and mutation of wheat rust races in Ethiopia has convinced farmers about the need to adopt newer, resistant varieties.”

The fourth most widely grown cereal after tef, maize, and sorghum, wheat in Ethiopia is produced largely by smallholder farmers under rainfed conditions. Wheat production and area under cultivation have increased significantly in the last decade and Ethiopia is among Africa’s top three wheat producers, but the country still imports on average 1.4 million tons of wheat per year to meet domestic demand.

National and international organizations such as EIAR, CIMMYT, and the International Centre for Agricultural Research in the Dry Areas (ICARDA) are working intensely to identify and incorporate new sources of disease resistance into improved wheat varieties and to support the multiplication of more seed to meet farmer demand.

New wheat varieties have provided bigger harvests and incomes for Ethiopia farmers in the last decade, but swiftly mutating and spreading disease strains are endangering wheat’s future, according to Dave Hodson, CIMMYT expert in geographic information and decision support systems, co-author of the new study.

Ethiopian wheat farmers like Abebe Abora, of Doyogena, have benefitted from adopting high-yielding wheat varieties but face threats from fast mutating races of wheat rust disease pathogens. Photo: CIMMYT/Apollo Habtamu.

“In addition to stripe rust, highly-virulent new races of stem rust are ruining wheat harvests in eastern Africa,” he explained. “These include the deadly Ug99 race group, which has spread beyond the region, and, more recently, the stem rust race TKTTF.”

As an example, he mentioned the case of the wheat variety Digalu, which is resistant to stripe rust and was quickly adopted by farmers after the 2010-11 epidemic. But Digalu has recently shown susceptibility to TKTTF stem rust and must now be replaced.

“In rust-prone Ethiopia, the risks of over-reliance on a widely-sown variety that is protected by a single, major resistance gene—Digalu, for example—are clearly apparent,” he added. “CIMMYT and partners are working hard to replace it with a new variety whose resistance is genetically more complex and durable.”

Hodson said as well that continuous monitoring of the rust populations in Ethiopia and the surrounding region is essential to detect and respond to emerging threats, as well as to ensure that the key pathogen races are used to screen for resistance in wheat breeding programs.

Hodson and partners at the John Innes Centre, UK, and EIAR are leading development of a handheld tool that allows rapid identification of disease strains in the field, instead of having to send them to a laboratory and lose precious time awaiting the results.

CIMMYT and partners are also applying molecular tools to study wheat varietal use in Ethiopia. “There are indications that yields reported by farmers were much lower than official statistics, and farmer recollections of varietal names and other information are not always exact,” Hodson explained. “We are analyzing results now of a follow-up study that uses DNA fingerprinting to better document varietal use and turnover.”

The authors would like to acknowledge the Standing Panel for Impact Assessment (SPIA) for financing, the Diffusion and Impacts of Improved Varieties in Africa (DIIVA) project that supported the first survey in 2011, and Cornell University, the Bill & Melinda Gates Foundation, and United Kingdom’s Department for International Development (DFID) through the Durable Rust Resistance in Wheat (DRRW, now called Delivering Genetic Gain in Wheat) project for support for the second survey in 2014.

Pictured are Martin Kropff, CIMMYT director general (left) and Mustapha El-Bouhssini, ICARDA entomologist, in that center’s lab at Rabat, Morocco.

In an excellent example of scientific collaboration spanning borders and generations, Mustapha El-Bouhssini, entomologist at the International Centre for Agricultural Research in the Dry Areas (ICARDA), screened wheat breeding lines from the International Maize and Wheat Improvement Center (CIMMYT) under glasshouse infestations of Russian wheat aphid (Diuraphis noxia), a major global pest of wheat. At least one of the lines, which were developed through crosses of wheat with related crop and grass species, showed high levels of resistance.

Scientists at CIMMYT began research on sources of RWA resistance for wheat in the early 1990s. Good sources of resistance from rye were accessed via wide crosses that combined major portions of both crop’s chromosomes, in collaborative work led by Adam J. Lukaszewski, University of California, Riverside.

“In our experiments, we did an initial screening with one replication and then a replicated test with a Pavon line and the check,” said El-Bouhssini.

Pavon is a semi-dwarf wheat variety developed by Sanjaya Rajaram, former CIMMYT wheat director and 2014 World Food Prize laureate. The version of Pavon referred to by El-Bouhssini had been crossed with rye by Lukaszewski and entered CIMMYT’s wheat genetic resource collections; the check was a popular high-yielding variety with no resistance to Russian wheat aphid.

Pavon had been used by Lukaszewski and colleagues as a model variety for wide crosses to transfer pest and disease resistance to wheat from its distant relatives. More recently Leonardo Crespo-Herrera, CIMMYT wheat breeder, pursued this research for his doctoral studies. It was he who provided a selection of wide-cross lines to El-Bouhssini.

“Resistance to pests in wheat is a valuable trait for farmers and the environment,” said Crespo-Herrera. “It can protect yield for farmers who lack access to other control methods. For those with access to insecticides, it can minimize their use and cost, as well as negative impacts on the environment and human health.”

The resistant wheat line (center) is green while all others have perished under heavy infestation of Russian wheat aphid, in the ICARDA entomology lab at Rabat, Morocco.

This blast-infected wheat spike contains no grain, only chaff. Photo: CIMMYT files

By Gideon Kruseman and Mike Listman

A spatial mapping and ex ante study regarding the risk and potential spread in South Asia of wheat blast, a mysterious and deadly disease from the Americas that unexpectedly infected wheat in southwestern Bangladesh in 2016, identified 7 million hectares of wheat cropping areas in Bangladesh, India, and Pakistan whose agro-climatic conditions resemble those of the Bangladesh outbreak zone.

The study shows that, under a conservative scenario of 5-10% wheat blast production damage in a single season in those areas, wheat grain losses would amount to from 0.89 to 1.77 million tons, worth between $180 and $350 million. This would strain the region’s already fragile food security and force up wheat imports and prices, according to Khondoker Abdul Mottaleb, first author of the study.

“Climate change and related changes in weather patterns, together with continuing globalization, expose wheat crops to increased risks from pathogens that are sometimes transported over long distances,” said Mottaleb.

Foresight research at the International Maize and Wheat Improvement Center (CIMMYT) has focused on new diseases and pests that have emerged or spread in recent decades, threatening global food safety and security. For wheat these include Ug99 and other new strains of stem rust, the movement of stripe rust into new areas, and the sudden appearance in Bangladesh of wheat blast, which had previously been limited to South America.

“As early as 2011, CIMMYT researchers had warned that wheat blast could spread to new areas, including South Asia,” said Kai Sonder, who manages CIMMYT’s geographic information systems lab and was a co-author on the current study, referring to a 2011 note published by the American Pathological Society. “Now that forecast has come true.”

CIMMYT has played a pivotal role in global efforts to study and control blast, with funding from the Australian Center for International Agricultural Research (ACIAR), the CGIAR Research Program on Wheat (WHEAT), the Indian Council of Agriculture Research (ICAR), and the United States Agency for International Development (USAID).

This has included the release by Bangladesh of the first blast resistant, biofortified wheat variety in 2017, using a CIMMYT wheat line, and numerous training events on blast for South Asia researchers.

Click here to read the article in PLOS-One: “Threat of wheat blast to South Asia’s food security: An ex-ante analysis.”

Photo: CIMMYT/Tim Krupnik

Fourteen young wheat researchers from South Asia recently attended a screening and surveillance course to address wheat blast, the mysterious and deadly disease whose surprise 2016 outbreak in southwestern Bangladesh devastated that region’s wheat crop, diminished farmers’ food security and livelihoods, and augured blast’s inexorable spread in South Asia.

Held from 24 February to 4 March 2018 at the Regional Agricultural Research Station (RARS), Jessore, as part of that facility’s precision phenotyping platform to develop resistant wheat varieties, the course emphasized hands-on practice for crucial and challenging aspects of disease control and resistance breeding, including scoring infections on plants and achieving optimal development of the disease on experimental wheat plots.

Cutting-edge approaches tested for the first time in South Asia included use of smartphone-attachable field microscopes together with artificial intelligence processing of images, allowing researchers identify blast lesions not visible to the naked eye.

“A disease like wheat blast, which respects no borders, can only be addressed through international collaboration and strengthening South Asia’s human and institutional capacities,” said Hans-Joachim Braun, director of the global wheat program of the International Maize and Wheat Improvement Center (CIMMYT), addressing participants and guests at the course opening ceremony. “Stable funding from CGIAR enabled CIMMYT and partners to react quickly to the 2016 outbreak, screening breeding lines in Bolivia and working with USDA-ARS, Fort Detrick, USA to identify resistance sources, resulting in the rapid release in 2017 of BARI Gom 33, Bangladesh’s first-ever blast resistant and zinc enriched wheat variety.”

Cooler and dryer weather during the 2017-18 wheat season has limited the incidence and severity of blast on Bangladesh’s latest wheat crop, but the disease remains a major threat for the country and its neighbors, according to P.K. Malaker, Chief Scientific Officer, Wheat Research Centre (WRC) of the Bangladesh Agricultural Research Institute (BARI).

“We need to raise awareness of the danger and the need for effective management, through training courses, workshops, and mass media campaigns,” said Malaker, speaking during the course.

The course was organized by CIMMYT, a Mexico-based organization that has collaborated with Bangladeshi research organizations for decades, with support from the Australian Center for International Agricultural Research (ACIAR), Indian Council of Agricultural Research (ICAR), CGIAR Research Program on Wheat (WHEAT), the United States Agency for International Development (USAID), and the Bangladesh Wheat and Maize Research Institute (BWMRI).

Speaking at the closing ceremony, N.C.D. Barma, WRC Director, thanked the participants and the management team and distributed certificates. “The training was very effective. BMWRI and CIMMYT have to work together to mitigate the threat of wheat blast in Bangladesh.”

Other participants included Jose Mauricio Fernandes, EMBRAPA-Passo Fundo, Brazil; Pawan Singh, CIMMYT wheat pathologist; T.P. Tiwari, Timothy J. Krupnik, and D.B. Pandit, CIMMYT-Bangladesh; Bahadur Mia, Bangladesh Agricultural University (BAU); and scientists from BMWRI and BARI, the Nepal Agricultural Research Council NARC, and Assam Agricultural University (AAU), India.

Iván Ortíz-Monasterio, expert on sustainable intensification and wheat crop management at the International Maize and Wheat Improvement Center (CIMMYT), recently took part in a study detailing the detriments of excess fertilizer use and the benefits of more precise dosages.

In the following interview, he discusses the overuse of nitrogen fertilizer and related consequences, his experience with farmers, and his outlook for the future. According to Ortíz-Monasterio and study co-authors, research on wheat in the Yaqui Valley, state of Sonora, northwestern Mexico, and home to CIMMYT’s Norman E. Borlaug Experiment Station (CENEB), has direct implications for wheat crop management worldwide.

“The Yaqui Valley is agro-climatically representative of areas where 40 percent of the world’s wheat is grown, including places like the Indo-Gangetic Plains of India and Pakistan, the Nile Delta in Egypt, and the wheat lands of China,” said Ortíz-Monasterio.

1. A key finding of the new publication was that, after a certain point, applying more nitrogen fertilizer does not increase yields, making excessive applications essentially a drain on farmers’ resources. Why then do farmers continue to apply more fertilizer than the crop needs?

Well there is a risk, if you under-apply N fertilizer, your yield goes down. Farmers are afraid that the yield will be lower and that their profit will be lower. The cost of under-applying for them is greater than the cost of over-applying, because they’re not paying all the costs of over applying. Those costs include the environmental impacts associated with greenhouse gas emissions, at a regional scale in the case of the Yaqui Valley because of nitrification of the Sea of Cortez, and at a local level due to contamination of the water table. All these costs are passed on to society. If we passed them on to farmers, then they would be more concerned about over-applying nitrogen fertilizers.

-Do you think farmers becoming more concerned is something that could happen?

Well there are starting to be more regulations in Europe. In the UK, farmers cannot apply any nitrogen before or at sowing; they can apply fertilizer only once the plant is about 15 centimeters tall. In other parts of Europe, like Germany, farmers cannot apply more than 150 kilograms of nitrogen on wheat, so it’s happening in other parts of the world. The government of Mexico and others are making commitments to reduce nitrous oxide emissions by 20 percent by 2030 and, in the case of agriculture, the main source of nitrous oxide is nitrogen fertilizer. To meet such commitments, governments will have to take policy action so, yes; I think there’s a good chance something will happen.

2. There are technologies that can help farmers know precisely when to apply fertilizer and how much, for optimal crop yield and nitrogen use. Do many farmers use them? Why or why not?

Something interesting to me is what’s happening right now. For the last 10 years, we’ve been working with Yaqui Valley farmers to test and promote hand-held sensors and hiring farm advisors paid with government money who provide this service free to farmers, and adoption was high. Then the government removed the subsidy, expecting farmers to begin covering the cost, but

farmers didn’t want to pay for it.

Then a company that uses drones approached me and other researchers in the region and requested our help to convert wheat crop sensor data obtained using airborne drones to recommended fertilizer dosages. We agreed and, in their first year of operation, farmers growing wheat on 1,000 hectares paid for this service. I don’t know what it is—maybe seeing a colorful map is more sexy—but farmers seem to be willing to pay if you fly a drone to collect the data instead of having a farm advisor walk over the field. But it’s great! In the past we relied on the government to transfer the technology and now we have this  great example of a private-public partnership, where a company is helping to transfer the technology and making a profit, so that will make it sustainable. I’m very excited about that!

3. Does CIMMYT have a plan to increase adoption of these technologies?

A CIMMYT technician uses a hand-held sensor to measure NDVI (normalized difference vegetative index) in a wheat field at the center’s CENEB experiment station near Ciudad Obregón, Sonora, northern Mexico. Photo: CIMMYT.

We’re not married to one technology, but need to work with all of them. You know we started with Greekseeker, which is a ground-based sensor, and now we’re also working with drones, with manned airplanes mounted with cameras, and even satellite images. So, there are four different ways to collect the data, and we’ve seen that the Greenseeker results correlate well with all of them, so the technology we developed originally for Greenseeker can be used with all the other platforms.

4. Are you optimistic that farmers can shift their perceptions in this area and significantly reduce their nitrogen use?

I think we’re moving in that direction, but slowly. We need policy help from the government. Officials need to give some type of incentive to farmers to use the technology, because when farmers do something different they see it as a risk. To compensate for that risk, give them a carrot, rather than a stick, and I think that will help us move the technology faster.

In a letter to the editors* of Nature, John R. Porter, Chair of the Independent Steering Committee for the CGIAR Research Program on Wheat, and Tony Fischer, Honorary Research Fellow, CSIRO Plant Industry, Australia, and former Director of the CIMMYT Wheat Program, along with other leading crop scientists, question where functional plant genomics research is headed. Their letter stems from a recent Editorial about reported progress in the 11th Plant Genomes Meeting. Porter et al. ask “what has been gained from decoding the alphabet of gene sequences,” and “when will the promise of genetics be translated into higher yields in farmers’ fields?”

“The best and most relevant research for crop science begins and ends in the field,” say Porter et al.

They call for an interdisciplinary approach aligning functional genomics with crop agronomy, while keeping food security in clear sight and contributing to the yield growth in crop production required to feed billions more consumers in coming decades.

* Full access requires a subscription to Nature or purchase of the letter.

A wheat farm family from the Yaqui Valley, northwestern Mexico. Photo: CIMMYT/Peter Lowe

EL BATÁN, MEXICO – 24 APRIL 2018–Farmers of irrigated wheat can increase profits and radically reduce greenhouse gas emissions by applying fertilizer in more precise dosages, according to a new study.

Published today in the journal Agriculture, Ecosystems and Environment, the study shows that farmers in the Yaqui Valley, a major breadbasket region in northwestern Mexico that covers over 1.5 times the area of the Mexico City, are applying significantly more nitrogen fertilizer than they need to maximize wheat yields.

Lower application of nitrogen fertilizer would cut the region’s yearly emissions of nitrous oxide, a potent greenhouse gas, by the equivalent of as much as 130,000 tons of carbon dioxide, equal to the emissions of 14 million gallons of gasoline, according to Neville Millar, a senior researcher at Michigan State University (MSU) and first author of the published paper.

“Our study is the first to isolate the effect of multiple nitrogen fertilizer rates on nitrous oxide emissions in wheat in the tropics or sub-tropics,” Millar said. “It shows that applying fertilizer to wheat at higher than optimal economic rates results in an exponential increase in nitrous oxide emissions.”

Yaqui Valley wheat farming conditions and practices are similar to those of huge wheat cropping expanses in China, India, and Pakistan, which together account for roughly half of worldwide nitrogen fertilizer use for wheat, according to study co-author Iván Ortíz-Monasterio, a wheat agronomist at the International Maize and Wheat Improvement Center (CIMMYT), whose Yaqui Valley experiment station was the site of the reported research.

“The recommendations are thus globally relevant and represent a potential triple win, in the form of reduced greenhouse gas emissions, higher income for farmers and continued high productivity for wheat cropping,” Ortíz-Monasterio said.

Measuring nitrous oxide after nitrogen fertilizer applications in spring durum wheat crops during two growing seasons, Millar and an international team of scientists found an exponential increase in emissions from plots fertilized at greater than economically-optimal rates—that is, when the extra nitrogen applied no longer boosts grain yield.

They also found that grain quality at the economically optimal N rates was not impacted and exceeded that required by local farmer associations for sale to the market. They examined five different nitrogen fertilizer dosages ranging from 0 to 280 kilograms per hectare.

“In our study, the highest dosage to get optimum wheat yields was 145 kilograms of nitrogen fertilizer per hectare in the 2014 crop,” said Millar. “Yaqui Valley farmers typically apply around 300 kilograms. The wheat crop takes up and uses only about a third of that nitrogen; the remainder may be lost to the atmosphere as gases, including nitrous oxide, and to groundwater as nitrate.”

Promoting profitable, climate-friendly fertilizer use

Farmers’ excessive use of fertilizer is driven largely by risk aversion and economic concerns, according to Ortíz-Monasterio. “Because crops in high-yielding years will require more nitrogen than in low-yielding years, farmers tend to be optimistic and fertilize for high-yielding years,” said Ortíz-Monasterio. “At the same time, since farmers don’t have data about available nitrogen in their fields, they tend to over-apply fertilizer because this is less costly than growing a crop that lacks the nitrogen to develop and yield near to full potential.”

Ortíz-Monasterio and his partners have been studying and promoting management practices to help farmers to use fertilizer more efficiently and take into account available soil nitrogen and weather. This technology, including Greenseeker, a handheld device that assesses plant nitrogen needs, was tested in a separate study for its ability to advise farmers on optimal rates of fertilizer use.

“Sensing devices similar to Greenseeker but mounted on drones are providing recommendations to Yaqui Valley farmers for wheat crops grown on more than 1,000 acres in 2017 and 2018,” Ortiz-Monasterio notes.

Part of a research partnership between CIMMYT and MSU’s W.K. Kellogg Biological Station (KBS) Long-Term Ecological Research program to reduce greenhouse gas impacts of intensive farming, a key aim of the present study was to generate new emission factors for Mexican grain crops that accurately reflect nitrous oxide emissions and emission reductions and can be used in global carbon markets, according to Millar.

“The emission calculations from our work can be incorporated by carbon market organizations into carbon market protocols, to help compensate farmers for reducing their fertilizer use,” he said.

“This study shows that low emissions nitrogen management is possible in tropical cereal crop systems and provides important guidance on the optimal levels for large cropping areas of the world,” said Lini Wollenberg, an expert in low-emissions agriculture for the CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS), which helped fund the research. “With these improved emission factors, countries will be able to better plan and implement their commitments to reducing emissions.

To view the article

Millar, N., A. Urrea, K. Kahmark, I. Shcherbak, G. P. Robertson, and I. Ortiz-Monasterio. 2018. Nitrous oxide (N2O) flux responds exponentially to nitrogen fertilizer in irrigated wheat in the Yaqui Valley, Mexico. Agriculture, Ecosystems and Environment, https://doi.org/10.1016/j.agee.2018.04.003.

KBS LTER
Michigan State University’s Kellogg Biological Station Long-term Ecological Research (KBS LTER) Program studies the ecology of intensive field crop ecosystems as part of a national network of LTER sites established by the National Science Foundation. More information at https://lter.kbs.msu.edu

MSU AgBioResearch
MSU AgBioResearch engages in innovative, leading-edge research that combines scientific expertise with practical experience to help advance FOOD, ENERGY and the ENVIRONMENT. It encompasses the work of more than 300 scientists in seven MSU colleges — Agriculture and Natural Resources, Arts and Letters, Communication Arts and Sciences, Engineering, Natural Science, Social Science and Veterinary Medicine — and includes a network of 13 outlying research centers across Michigan.

CIMMYT
The International Maize and Wheat Improvement Center (CIMMYT) is the global leader in publicly-funded maize and wheat research and related farming systems. Headquartered near Mexico City, CIMMYT works with hundreds of partners throughout the developing world to sustainably increase the productivity of maize and wheat cropping systems, thus improving global food security and reducing poverty. CIMMYT is a member of the CGIAR System and leads the CGIAR Research Programs on Maize and Wheat and the Excellence in Breeding Platform. The Center receives support from national governments, foundations, development banks and other public and private agencies. For more information, visit www.cimmyt.org.

CCAFS
The CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS), led by the International Center for Tropical Agriculture (CIAT), brings together some of the world’s best researchers in agricultural science, development research, climate science and earth system science to identify and address the most important interactions, synergies and tradeoffs between climate change, agriculture and food security. CCAFS is carried out with support from CGIAR Fund Donors and through bilateral funding agreements. www.ccafs.cgiar.org