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How effective soil aggregate management can boost productivity and climate resilience

Written by dmedina on . Posted in News.

Soils are the bedrock for plant health and sustenance, but how do we protect and enhance them to maximize their nutritional potential? Years of conventional farming practices have left many soils depleted, raising urgent concerns about how to rejuvenate them. The recent El Niño event during the 2023/24 farming season in southern Africa, bringing extreme weather conditions—ranging from prolonged droughts to intense floods—has exposed the vulnerability of these soils. Poorly managed soils, already strained by years of excessive tillage and lack of cover, struggle to retain moisture under such stress, leading to crop failures even after rainfall.

However, conservation agriculture (CA) offers a vital solution. By improving soil structure and moisture retention, CA practices provide a lifeline for crops in challenging conditions. Recognizing this, CIMMYT scientists are actively promoting CA among smallholder farmers across sub-Saharan Africa, highlighting its critical role in sustaining soil health and resilience in the face of climate challenges.

Isaiah Nyagumbo demonstrating soil aggregate stability (CIMMYT)

Described as lumps of soil particles that bind together strongly, soil aggregates play a vital role in maintaining soil health, supporting plant growth, and sustaining agricultural productivity. Formed by the combined effects of biological, chemical, and physical processes, the structure and stability of soil aggregates are crucial for several soil functions—primarily water infiltration, root growth, and resistance to erosion. Soil aggregates consist of various soil particles, including sand, silt, clay, and organic matter. There are different types of soil aggregates, including macroaggregates (>0.25 mm) and microaggregates (<0.25 mm), with macroaggregates typically more stable and beneficial for soil structure and functions.

Demonstrating the value of soil aggregate stability
A CIMMYT researcher holding a soil aggregate from a CA field (CIMMYT)

Imagine three soil aggregate samples taken from the same field but under different management regimes—from virgin soil that has not been previously cropped, to land under conservation agriculture practices for the last 5 to 8 years, and soil conventionally ploughed annually before crop planting for many years. When these soil aggregates are gently immersed in clear water, stark differences can be noted. The aggregates from conventionally tilled soil, weakened by years of intensive cultivation, quickly disintegrate, turning the water murky and brown.

In contrast, the aggregates from virgin soil remain intact, preserving the water’s clarity even after several hours. The CA soil aggregates exhibit much better stability than those from the conventionally tilled soil but fail to remain as intact as those from the natural virgin soil. A simple lesson is drawn from this demonstration! Restoring degraded soils is a serious challenge. Even after 5 years of CA practices, soil organic carbon levels may only show modest improvement, and the aggregates, while more stable, still don’t match the condition of aggregates from virgin soil.

Soil recovery from a degraded state is a slow process that is not “a walk in the park.” Transitioning from conventional tillage to CA is challenging and slow, requiring years to rebuild organic matter and improve aggregate stability. Patience and careful soil management are vital, as degradation can occur rapidly, but recovery is a lengthy process. However, incorporating organic soil amendments like manure and compost, along with diversifying crops by introducing legumes such as cowpea, groundnut, soybean, mucuna, and pigeon pea, can accelerate this recovery. While degradation occurs rapidly, soil restoration demands a long-term commitment, but the rewards are worth the effort.

Exploring conservation agriculture as a source to improve soil health

Conservation agriculture is built on three key principles: reduced soil disturbance, permanent soil cover, and diverse crop rotation. Minimizing soil disturbance helps preserve soil structure, while permanent soil cover shields the soil against splash erosion and boosts microbial activity. Crop rotation enhances soil fertility, maintains aggregate structure, and disrupts pest and disease cycles. These principles are essential for soil recovery and the retention of organic matter.

Among these, permanent soil cover is often the most challenging for farmers to implement, yet it is critical for effective soil management. Demonstrating its importance, a simple test with water applied to soil samples with varying levels of cover illustrates splash erosion effects.

“Such a simple test mimics real-life conditions farmers face during rains. Soils without cover suffer significant erosion, while those with minimal or substantial cover show reduced erosion and improved water retention. This emphasizes the importance of maintaining permanent soil cover to foster microbial activity and enhance soil health,” highlighted Isaiah Nyagumbo, cropping systems agronomist.

In a nutshell, soil aggregate management is fundamental to climate resilience and agricultural sustainability. Through the adoption of conservation agriculture practices, smallholder farmers can significantly improve soil health, enhance water and nutrient retention, and increase crop resilience to climate stress. The journey from degraded to healthy soil is long and challenging, but with careful management and patience, the benefits are profound and lasting. By understanding and implementing these principles, farmers can build a more sustainable and resilient food system.

Digging in the Dirt: Detailed soil maps guide decision-making, from the field to the policy room

Written by Julian Bañuelos-Uribe on . Posted in Blogs.

When a non-farmer looks upon a field, they might just see it as an expanse of dirt and give no more thought to it. But to a farmer, that dirt is soil, the lifeblood of agriculture. Among other things, soil delivers necessary nutrients to crops, allowing them to grow and flourish.

About 95% of the food consumed around the world grows from soil, which is rapidly deteriorating because of unsustainable human activity. Around 33% of all soils around the world are degraded, meaning they can no longer sustain the same level of agricultural activity. This leads to lower crop yields, which potentially leads farmers to increase their use of fertilizer to overcome the damaged soil. But increased nitrogen fertilizer use has profound climate change effects, as poor fertilizer management, including overuse, can lead to nitrous oxide (a greenhouse gas) leaking into the air and nitrates into groundwater, rivers, and other water systems.

Sampling points in the state of Celaya, Guanajuato Mexico. (Photo: CIMMYT)

An important implement in the effort to preserve soil fertility is the practice of soil mapping, a process which produces detailed physical and chemical soil properties within a region. Things like the amount of nutrients, acidity, water conductivity, and bulk density, help guide decision making from individual farmers all the way to regional and national stakeholders.

The Sustainable Productivity Growth Coalition, a United Nations initiative which aims to accelerate the transition to more sustainable food systems through a holistic approach to productivity growth to optimize agricultural sustainability, featured soil mapping as an innovative, evidence-based approach for accelerating sustainable productivity growth in its 2023 report.

A global soil mapping initiative is underway led by the Food and Agriculture Organization of the United Nations (FAO) and the Global Soil Partnership with important contributions from CIMMYT scientist working in Mexico.

“Soil mapping of an agricultural region for chemical and physical soil properties offers a range of benefits that can significantly improve agricultural practices, land management, and overall productivity,” said Ivan Ortiz Monasterio, CIMMYT principal scientist.

Map for Phosphorus Bray 1. (Photo: CIMMYT)

Soil maps = blueprints

Using up-to-date soil information at the national scale can help to plan agricultural and land planning interventions and policies, by excluding areas with higher carbon content or fertility from urbanization plans, or by planning the implementation of irrigation schemes with high-quality water in salt-affected areas.

For farmers, there are many benefits, including the creation of nutrient management plans, which are perhaps the most important. These plans guide decisions about application rates and timing of inputs like fertilizers, help avoid over-application, and reduce the risk of runoff and pollution. This supports sustainable agriculture while reducing costs and minimizing nutrient pollution.

Map for zinc. (Photo: CIMMYT)

“There are many other benefits,” said Ortiz Monasterio. “From improved irrigation management, to informed crop decisions, to things like climate resilience because more fertile soils are better able to cope with the challenges of climate variation.”

Bringing voluntary carbon offset markets to smallholder Indian farmers

Written by Sarah McLaughlin on . Posted in Features.

To mitigate their amount of greenhouse gas (GHG) emissions, companies and individuals have access to international voluntary carbon offset markets, which are trading systems that financially compensate credit producer participants for offsetting the amount of carbon emitted. An innovative new initiative from the International Maize and Wheat Improvement Center (CIMMYT) and the Indian Council of Agricultural Research Institute (ICAR) is working to establish carbon markets among smallholder farmers in India, with the goal of reducing GHG emissions, encouraging climate smart farming practices through financial incentives.

In India, agriculture is one of the biggest sources of GHG emissions – between 14 and 21 percent of all GHGs are attributable to agricultural activities, which derive from the use of farm machinery, rice cultivation, fertilizer use, and other activities. Emissions from agriculture are increasing drastically due to synthetic fertilizers and enteric fermentation from livestock.

Within CIMMYT’s farmer-centered approach, participants in voluntary carbon markets will improve their own financial viability in two ways – through adopting sustainable practices and through receipt of payments from carbon markets. The approach will also employ regenerative interventions such as direct dry seeding of rice, minimal tillage, crop diversification, use of biofertilizers, and perennial cropping all while contributing to an overall reduction in GHG emissions.

“Working with ICAR to engage smallholder farmers with high-quality carbon offsets allows the farmers to offset their unavoidable emissions,” said Vijesh Krishna, senior CIMMYT scientist. “This program promotes inclusiveness because this newly created income is distributed among participating farmers, thereby improving their income.”

These regenerative agriculture interventions will increase and retain soil’s carbon content, water permeability and retention, resulting in crops’ ability to withstand drought, flooding, and temperature stresses. Only a small percentage of farmers currently implement these methods in India.

CIMMYT and ICAR researchers estimate that widespread adoption of these practices, combined with upgraded technologies, has the potential to return the carbon levels in agricultural soils from an average of 0.5 percent back to 1.5 percent. At present, the agricultural soils of India are poor with respect to soil organic carbon.

Carbon markets for smallholders

About 2,000 small holder farmers of Punjab, Haryana, and parts of Maharashtra, all in India, are enrolled in the project through individual partnership agreements. Once farmers implement regenerative agricultural methods, they will be eligible to receive payments for carbon credits generated for 10 to 20 years, conditional upon continuing to use climate-smart practices.

“We believe these efforts can be expanded to other regions of India, and other countries,” said Sieg Snapp, CIMMYT’s Sustainable Agrifood Systems (SAS) program director. “Helping farmers and reducing GHG emissions at the same time is the way forward in dealing the crisis of climate change.”

Farms are geo-tagged and monitored using remote sensing for regenerative farming practices, and soil carbon content will be measured at the beginning and end of the crop cycle. Those that produce rice and wheat with a lower carbon footprint will be identified, so their produce gets purchase and price preferences from those who want to promote lower carbon agriculture.

Digital agronomy tools and satellite imagery analysis to measure and verify soil carbon offsets and on-farm GHG emission levels are essential for scaling small farmer-centered carbon projects. The veracity, transparency, and traceability of each carbon offset have direct implications for its credibility and actual market value. CIMMYT will contribute towards a Measurement, Reporting, and Verification (MRV) platform to expand climate action country-wide.

So far, CIMMYT and ICAR researchers estimate that the enrolled smallholder famers have sequestered between four and five tons of carbon dioxide. After independent third-party auditors verify the data, farmers will be paid based on the amount of GHG reduction, with the first carbon offset payments expected to be issued in 2023.

Cover photo: A green maize seedling emerges from the soil (Photo: Wasim Iftikar/CIMMYT)

Nepal launches digital soil map

Written by Rodrigo Ordóñez on . Posted in Features.

A new digital soil map for Nepal provides access to location-specific information on soil properties for any province, district, municipality or a particular area of interest. The interactive map provides information that will be useful to make new crop- and site-specific fertilizer recommendations for the country.

Produced by the International Maize and Wheat Improvement Center (CIMMYT), in collaboration with Nepal Agricultural Research Council’s (NARC) National Soil Science Research Center (NSSRC), this is the first publicly available soil map in South Asia that covers the entire country.

The Prime Minister of Nepal, K.P. Sharma Oli, officially launched the digital soil map at an event on February 24, 2021. Oli highlighted the benefits the map would bring to support soil fertility management in the digital era in Nepal. He emphasized its sustainability and intended use, mainly by farmers.

CIMMYT and NSSRC made a live demonstration of the digital soil map. They also developed and distributed an informative booklet that gives an overview of the map’s major features, operation guidelines, benefits, management and long-term plans.

The launch event was led by the Ministry of Agriculture and Livestock Development and organized in coordination with NARC, as part of the Nepal Seed and Fertilizer (NSAF) project, implemented by CIMMYT. More than 200 people participated in the event, including government officials, policymakers, scientists, professors, development partner representatives, private sector partners and journalists. The event was also livestreamed.

Better decisions

Immediately after the launch of the digital soil map, its CPU usage grew up to 94%. Two days after the launch, 64 new accounts had been created, who downloaded different soil properties data in raster format for use in maps and models.

The new online resource was prepared using soil information from 23,273 soil samples collected from the National Land Use Project, Central Agricultural Laboratory and Nepal Agricultural Research Council. The samples were collected from 56 districts covering seven provinces. These soil properties were combined with environmental covariates (soil forming factors) derived from satellite data and spatial predictions of soil properties were generated using advanced machine learning tools and methods.

The platform is hosted and managed by NARC, who will update the database periodically to ensure its effective management, accuracy and use by local government and relevant stakeholders. The first version of the map was finalized and validated through a workshop organized by NSSRC among different stakeholders, including retired soil scientists and university professors.

Ivan Ortiz-Monasterio, principal scientist at CIMMYT, shared his remarks in a video message. (Photo: Shashish Maharjan/CIMMYT)
Ivan Ortiz-Monasterio, principal scientist at CIMMYT, shared his remarks in a video message. (Photo: Shashish Maharjan/CIMMYT)

“The ministry can use the map to make more efficient management decisions on import, distribution and recommendation of appropriate fertilizer types, including blended fertilizers. The same information will also support provincial governments to select suitable crops and design extension programs for improving soil health,” said Padma Kumari Aryal, Minister of Agriculture and Livestock Development, who chaired the event. “The private sector can utilize the acquired soil information to build interactive and user-friendly mobile apps that can provide soil properties and fertilizer-related information to farmers as part of commercial agri-advisory extension services,” she said.

“These soil maps will not only help to increase crop yields, but also the nutritional value of these crops, which in return will help solve problems of public health such as zinc deficiency in Nepal’s population,” explained Ivan Ortiz-Monasterio, principal scientist at CIMMYT, in a video message.

Yogendra Kumar Karki, secretary of the Ministry of Agriculture and Livestock Development, presented the program objectives and Deepak Bhandari, executive director of NARC, talked about the implementation of the map and its sustainability. Special remarks were also delivered by USAID Nepal’s mission director, the secretary of Livestock, scientists and professors from Tribhuwan University, the International Fertilizer Development Center (IFDC) and the International Centre for Integrated Mountain Development (ICIMOD).

K.P. Sharma Oli (left), Prime Minister of Nepal, and Padma Kumari Aryal, Minister of Agriculture and Livestock Development, launch the digital soil map. (Photo: Shashish Maharjan/CIMMYT)
K.P. Sharma Oli (left), Prime Minister of Nepal, and Padma Kumari Aryal, Minister of Agriculture and Livestock Development, launch the digital soil map. (Photo: Shashish Maharjan/CIMMYT)

Benefits of digital soil mapping

Soil properties affect crop yield and production. In Nepal, access to soil testing facilities is rather scarce, making it difficult for farmers to know the fertilizer requirement of their land. The absence of a well-developed soil information system and soil fertility maps has been lacking for decades, leading to inadequate strategies for soil fertility and fertilizer management to improve crop productivity. Similarly, existing blanket-type fertilizer recommendations lead to imbalanced application of plant nutrients and fertilizers by farmers, which also negatively affects crop productivity and soil health.

This is where digital soil mapping comes in handy. It allows users to identify a domain with similar soil properties and soil fertility status. The digital platform provides access to domain-specific information on soil properties including soil texture, soil pH, organic matter, nitrogen, available phosphorus and potassium, and micronutrients such as zinc and boron across Nepal’s arable land.

Farmers and extension agents will be able to estimate the total amount of fertilizer required for a particular domain or season. As a decision-support tool, policy makers and provincial government can design and implement programs for improving soil fertility and increasing crop productivity. The map also allows users to identify areas with deficient plant nutrients and provide site-specific fertilizer formulations; for example, determining the right type of blended fertilizers required for balanced fertilization programs. Academics can also obtain periodic updates from these soil maps and use it as a resource while teaching their students.

As digital soil mapping advances, NSSRC will work towards institutionalizing the platform, building awareness at the province and local levels, validating the map, and establishing a national soil information system for the country.

Nepal’s digital soil map is readily accessible on the NSSRC web portal:
https://soil.narc.gov.np/soil/soilmap/

A young man uses a precision spreader to distribute fertilizer in a field. (Photo: Mahesh Maske/CIMMYT)

Too much or never enough

Written by Emma Orchardson on . Posted in Blogs.

A young man uses a precision spreader to distribute fertilizer in a field. (Photo: Mahesh Maske/CIMMYT)
A young man uses a precision spreader to distribute fertilizer in a field in India. (Photo: Mahesh Maske/CIMMYT)

Although nitrogen has helped in contributing to human dietary needs, there are still large areas of the world — namely sub-Saharan Africa and parts of Asia — that remain short of the amounts they need to achieve food and nutritional security.  

Conversely, synthetic nitrogen has become increasingly crucial in today’s intensive agricultural systems, but nearly half of the fertilizer nitrogen applied on farms leaks into the surrounding environment. It is possible that we have now transgressed the sustainable planetary boundary for nitrogen, and this could have devasting consequences.  

Given this conflicting dual role this compound plays in agricultural systems and the environment — both positive and negative — the nitrogen challenge is highly relevant across most of the 17 Sustainable Development Goals (SDGs) established by the United Nations. 

Facing a global challenge 

The challenge of nitrogen management globally is to provide enough nitrogen to meet global food security while minimizing the flow of unused nitrogen to the environment. One of the key approaches to addressing this is to improve nitrogen use efficiency – which not only enhances crop productivity but also minimizes environmental losses through careful agronomic management – and measures to improve soil quality over time. 

Globally, average nitrogen use efficiency does not exceed 50%. Estimates show that a nitrogen use efficiency will need to reach 67% by 2050 if we are to meet global food demand while keeping surplus nitrogen within the limits for maintaining acceptable air and water qualities to meet the SDGs. 

This target may seem ambitious — especially given the biological limits to achieving a very high nitrogen use efficiency — but it is achievable.  

Earlier this year, J.K. Ladha and I co-authored a paper outlining the links between nitrogen fertilizer use in agricultural production systems and various SDGs. For instance, agricultural systems with suboptimal nitrogen application are characterized with low crop productivity, spiraling into the vicious cycle of poverty, malnutrition and poor economy, a case most common in the sub-Saharan Africa. These essentially relate to SDG 1 (no-poverty), 2 (zero-hunger), 3 (good health and well-being), 8 (decent work and economic growth) and 15 (life on land).  

On the other hand, excess or imbalanced fertilizer nitrogen in parts of China and India have led to serious environmental hazards, degradation of land and economic loss. Balancing the amount of N input in these regions will contribute in achieving the SDG 13 (climate action). Equally, meeting some of the additional SDGs (5, gender equality; 6, clean water and sanitation; 10: reduced inequalities; etc.) requires optimum nitrogen application, which will also ensure “responsible consumption and production” (SDG 12). 

A diagram shows the impact of fertilizer nitrogen use on the achievement of the Sustainable Development Goals. (Graphic: CIMMYT/Adapted from CCAFS)
A diagram shows the impact of fertilizer nitrogen use on the achievement of the Sustainable Development Goals. (Graphic: CIMMYT/Adapted from CCAFS)

So, how can we achieve this?  

Increased research quantifying the linkages between nitrogen management and the SDGs will be important, but the key to success lies with raising awareness among policy makers, stakeholders and farmers. 

Most agricultural soils have considerably depleted levels of soil organic matter. This is a central problem that results in agroecosystems losing their ability to retain and regulate the supply of nitrogen to crops. However, poor knowledge and heavy price subsidies are equally to blame for the excess or misuse of nitrogen.  

While numerous technologies for efficient nitrogen management have been developed, delivery mechanisms need to be strengthened, as does encouragement for spontaneous adaptation and adoption by farmers. Equally — or perhaps more importantly — there is a need to create awareness and educate senior officials, policy makers, extension personnel and farmers on the impact of appropriate soil management and intelligent use of nitrogen fertilizer, in conjunction with biologically integrated strategies for soil fertility maintenance.  

An effective and aggressive campaign against the misuse of nitrogen will be effective in areas where the compound is overused, while greater accessibility of nitrogen fertilizer and policies to move farmers towards soil quality improvement will be essential in regions where nitrogen use is currently sub-optimal. 

It is only through this combination of approaches to improved system management, agricultural policies and awareness raising campaigns that we can sufficiently improve nitrogen use efficiency — and meet the SDGs before it’s too late. 

Read the full study “Achieving the sustainable development goals in agriculture: the crucial role of nitrogen in cereal-based systems” in Advances in Agronomy. 

A collage of shows images relating to different stages of the nitrogen cycle. (Graphic: Alfonso Cortés/CIMMYT)

Nitrogen in agriculture

Written by Emma Orchardson on . Posted in Explainers.

Nitrogen is the most essential nutrient in crop production but also one of the most challenging to work with. The compound is central to global crop production — particularly for major cereals — but while many parts of the world do not have enough to achieve food and nutrition security, in others excess nitrogen from fertilizer leaks into the environment with damaging consequences. 

What is nitrogen? 

Around 78% of the Earth’s atmosphere is made up of nitrogen gas or N2 — a molecule made of two nitrogen atoms glued together by a stable, triple bond.  

Though it makes up a large portion of the air we breathe, most living organisms can’t access it in this form. Atmospheric nitrogen must go through a natural process called nitrogen fixation to transform before it can be used for plant nutrition.  

Why do plants need nitrogen? 

In both plants and humans, nitrogen is used to make amino acids — which make the proteins that construct cells — and is one of the building blocks for DNA. It is also essential for plant growth because it is a major component of chlorophyll, the compound by which plants use sunlight energy to produce sugars from water and carbon dioxide (photosynthesis). 

The nitrogen cycle 

The nitrogen cycle is the process through which nitrogen moves from the atmosphere to earth, through soils and is released back into the atmosphere — converting in and out of its organic and inorganic forms. 

It begins with biological nitrogen fixation, which occurs when nitrogen-fixing bacteria that live in the root nodules of legumes convert organic matter into ammonium and then nitrate. Plants are able to absorb nitrate from the soil and break it down into the nitrogen they need, while denitrifying bacteria convert excess nitrate back into inorganic nitrogen which is released back into the atmosphere. 

The process can also begin with lightning, the heat from which ruptures the triple bonds of atmospheric nitrogen, freeing its atoms to combine with oxygen and create nitrous oxide gas, which dissolves in rain as nitric acid and is absorbed by the soil. 

Excess nitrate or that lost through leaching — in which key nutrients are dissolved due to rain or irrigation — can seep into and pollute groundwater streams. 

A diagram shows the process through which nitrogen moves from the atmosphere to earth, through soils and is released back into the atmosphere – converting in and out of its organic and inorganic forms. (Graphic: Nancy Valtierra/CIMMYT)
A diagram shows the process through which nitrogen moves from the atmosphere to earth, through soils and is released back into the atmosphere – converting in and out of its organic and inorganic forms. (Graphic: Nancy Valtierra/CIMMYT)

What about nitrogen fertilizer? 

For thousands of years, humans didn’t need to worry about nitrogen, but by the turn of the Twentieth Century it was evident that intensive farming was depleting nitrate in the soil, which raised concerns about the world’s rising population and a possible food crisis.  

In 1908, a German chemist named Fritz Haber devised a process for combining atmospheric nitrogen and hydrogen under extreme heat and pressure to create liquid ammonia — a synthetic nitrogen fertilizer. He later worked with chemist and engineer Carl Bosch to industrialize this process and make it commercially available for farmers.  

Once production was industrialized, synthetic nitrogen fertilizer — used in combination with new, high-yielding seed varieties — helped drive the Green Revolution and significantly boost global agricultural production from the late 1960s onwards. During this time Mexico became self-sufficient in wheat production, as did India and Pakistan, which were on the brink of famine.  

In today’s intensive agricultural systems, synthetic nitrogen fertilizer has become increasingly crucial. Worldwide, companies currently produce over 100 million metric tons of this product every year, and the Food and Agriculture Organization of the United Nations predicts that demand will continue to rise steadily, especially in Africa and South Asia. 

Is it sustainable? 

As demand continues to rise worldwide, the challenge of nitrogen management is to provide enough to meet global food security needs while minimizing the flow of unused nitrogen — which is 300 times more polluting than carbon dioxide — to the environment.  

While many regions remain short of available nitrogen to achieve food and nutrition security, in others nearly half of the fertilizer nitrogen applied in agriculture is leaked into the environment, with negative consequences including increased environmental hazards, irreparable land degradation and the contamination of aquatic resources. 

This challenge can be addressed by improving nitrogen use efficiency — a complex calculation which often involves a comparison between crop biomass (primarily economic yield) or nitrogen content/uptake (output) and the nitrogen applied (input) through any manure or synthetic fertilizer.  Improving this ratio not only enhances crop productivity but also minimizes environmental losses through careful agronomic management and helps improve soil quality over time.  

Currently, average global nitrogen use efficiency does not exceed 50%, which falls short of the estimated 67% needed to meet global food demand in 2050 while keeping surplus nitrogen within the limits for maintaining acceptable air and water qualities.  

Cutting-edge technological options for nitrogen management are on the horizon, though in the short-term nitrogen use efficiency can best be improved at farmer-level, by targeting fertilizer application, use of slow-release nitrogen fertilizers, using precision nitrogen application tools (Green Seeker) or fertigation using micro irrigation. 

A woman in India uses a precision spreader to apply fertilizer on her farm. (Photo: Wasim Iftikar)
A woman in India uses a precision spreader to apply fertilizer on her farm. (Photo: Wasim Iftikar)

Blue-sky technology 

Much progress has been made in developing technologies for an efficient nitrogen management, which along with good agronomy are proven to enhance crop nitrogen harvest and nitrogen use efficiency with lower surplus nitrogen. 

Scientists are investigating the merits of biological nitrification inhibition, a process through which a plant excretes material which influences the nitrogen cycle in the soil. Where this process occurs naturally — in some grasses and wheat wild relatives — it helps to significantly reduce nitrogen emissions. 

In 2007, scientists discovered biological nitrification traits in a wheat relative and in 2018 they succeeded in transferring them into a Chinese spring wheat variety. The initial result showed low productivity and remains in the very early stages of development, but researchers are keen to assess whether this process could be applied to commercial wheat varieties in the future. If so, this technology could be a game changer for meeting global nitrogen use efficiency goals. 

A farmer assesses soil on his plot in Ethiopia. (Photo: Simret Yasabu/CIMMYT)

Taking stock of the national toolbox

Written by Emma Orchardson on . Posted in Features.

The Government of Ethiopia has consistently prioritized agriculture and sees it as a core component of the country’s growth. However, despite considerable efforts to improve productivity, poor management of soil health and fertility has been an ongoing constraint. This is mainly due to a lack of comprehensive site-and context-specific soil health and fertility management recommendations and dissemination approaches targeted to specific needs.

The government envisions a balanced soil health and fertility system that helps farmers cultivate and maintain high-quality and fertile soils through the promotion of appropriate soil-management techniques, provision of required inputs, and facilitation of appropriate enablers, including knowledge and finance.

So far, a plethora of different research-for-development activities have been carried out in support of this effort, including the introduction of tools which provide location-specific fertilizer recommendations. For example, researchers on the Taking Maize Agronomy to Scale in Africa (TAMASA) project, led by the International Maize and Wheat Improvement Center (CIMMYT), have created locally calibrated versions of Nutrient Expert® (NE) — a tool for generating fertilizer recommendations — for maize farmers in Ethiopia, Nigeria and Tanzania.

Nutrient Expert® is only one of the many fertilizer recommendation tools which have been developed in recent years covering different levels of applicability and accuracy across spatial scales and users, including smallholder farmers, extension agents and national researchers. However, in order to make efficient use of all the resources available in Ethiopia, there is a need to systematically evaluate the merits of each tool for different scales and use cases. To jump start this process, researchers from the TAMASA project commissioned an assessment of the tools and frameworks that have been developed, adapted and promoted in the country, and how they compare with one another for different use-cases. Seven tools were assessed, including Nutrient Expert®, the Ethiopian Soil Information System (EthioSIS) and RiceAdvice.

For each of these, the research team asked determined how the tool is currently being implemented — for example, as an app or as a generic set of steps for recommendation generation — and its data requirements, how robust the estimates are, how complicated the interface is, how easy it is to use, the conditions under which it performs well, and the spatial scale at which it works best.

Farmer Gudeye Leta harvests his local variety maize in Dalecho village, Gudeya Bila district, Ethiopia. (Photo: Peter Lowe/CIMMYT)
Farmer Gudeye Leta harvests his local variety maize in Dalecho village, Gudeya Bila district, Ethiopia. (Photo: Peter Lowe/CIMMYT)

Combining efforts and information

The results of this initial assessment indicate that the type of main user and the scale at which decisions are made varied from tool to tool. In addition, most of the tools considered have interactive interfaces and several — including Nutrient Expert® and RiceAdvice — have IT based platforms to automate the optimization of fertilizer recommendations and/or analyze profit. However, the source codes for all the IT based platforms and tools are inaccessible to end-users. This means that if further evaluation and improvements are to be made, there should be a means of collaborating with developers to share the back-end information, such as site-specific response curves and source codes.

Because most of the tools take different approaches to making fertilizer application site-specific, each of them renders unique strengths and trade-offs. For example, Nutrient Expert® may be considered strong in its approach of downscaling regionally calibrated responses to field level recommendations based on a few site-specific responses from farmers. By contrast, its calibration requires intensive data from nutrient omission trials and advice provision is time consuming.

Overall, the use of all the Site-Specific Decision-Support Tools (SSDST) has resulted in improved grain yields compared to when farmers use traditional practices, and this is consistent across all crops. On average, use of Nutrient Expert® improved maize, rice and wheat yields by 5.9%, 8.1% and 4.9%, respectively. Similarly, the use of RiceAdvice resulted in a 21.8% yield advantage.

The assessment shows that some of the tools are useful because of their applicability at local level by development agents, while others are good because of the data used to develop and validate them. However, in order to benefit the agricultural system in Ethiopia from the perspective of reliable fertilizer-use advisory, there is a need to develop a platform that combines the merits of all available tools. To achieve this, it has been suggested that the institutions who developed the individual tools join forces to combine efforts and information, including background data and source codes for IT based tools.

While the COVID-19 pandemic has disrupted efforts to convene discussions around this work, CIMMYT has and will continue to play an active advocacy role in supporting collaborative efforts to inform evidence-based reforms to fertilizer recommendations and other agronomic advice in Ethiopia and the wider region. CIMMYT is currently undertaking a more rigorous evaluation of these tools and frameworks as a follow up on the initial stocktaking activity.

2020 World Food Prize recognizes career devoted to fight hunger and climate change through soil conservation

Written by Ricardo Curiel on . Posted in News.

The World Food Prize Foundation is honoring the work of Rattan Lal, who dedicated his life to study the effect of soil health in food production and climate change mitigation. On October 15 he will receive the 2020 World Food Prize, considered the “Nobel Prize” of agriculture.

Lal, who serves as distinguished professor of Soil Science and founding director of the Carbon Management and Sequestration Center at Ohio State University, is a visionary who understood the intricate relationship between soil conservation, yield potential, nutrition and carbon sequestration.

“Dr. Lal’s innovative research demonstrated how healthy soils are a crucial component of sustainable agricultural intensification — enabling higher crop yields, while requiring less land, agrochemicals, tillage, water and energy”, announced the World Food Prize Foundation in a press release.

Lal becomes the 50th person to receive the World Food Prize since the late Norman Borlaug — 1970 Nobel Peace Prize laureate — established the award in 1987. The award acknowledges outstanding contributions to human development by individuals who significantly improve the quality, quantity and availability of food on a global scale.

“CIMMYT actively researches and promotes the sustainable farming practices that Dr. Lal studied and advocated for since the late 1980s, such as no tillage, residue retention and crop rotation, which combined with new precision farming technologies help farmers increase yields, reduce food production costs and protect the environment”, said Bram Govaerts, Integrated Development director and representative for the Americas at the International Maize and Wheat Improvement Center (CIMMYT).

The World Food Prize has a long association with CIMMYT. Sanjaya Rajaram was awarded the 2014 World Food Prize for his work that led to a prodigious increase in world wheat production. Evangelina Villegas and Surinder Vasal were awarded the 2000 World Food Prize for their work on productivity and nutritional content of maize. Bram Govaerts received the Norman Borlaug Field Award in 2014. As an institution, CIMMYT received the Norman Borlaug Field Medallion in 2014.

Hafiz Uddin, a farmer from Ulankhati, Tanpuna, Barisal, Bangladesh. He used seeder fertilizer drills to plant mung beans on one acre of land, which resulted in a better yield than planting manually. (Photo: Ranak Martin)

Policy brief highlights opportunities to promote balanced nutrient management in South Asia

Written by Matthew O'Leary on . Posted in Publications.

Hafiz Uddin, a farmer from Ulankhati, Tanpuna, Barisal, Bangladesh. He used seeder fertilizer drills to plant mung beans on one acre of land, which resulted in a better yield than planting manually. (Photo: Ranak Martin)
Hafiz Uddin, a farmer from Ulankhati, Tanpuna, Barisal, Bangladesh. He used seeder fertilizer drills to plant mung beans on one acre of land, which resulted in a better yield than planting manually. (Photo: Ranak Martin)

Over the last few decades, deteriorating soil fertility has been linked to decreasing agricultural yields in South Asia, a region marked by inequities in food and nutritional security.

As the demand for fertilizers grows, researchers are working with government and businesses to promote balanced nutrient management and the appropriate use of organic amendments among smallholder farmers. The Cereal Systems Initiative for South Asia (CSISA) has published a new policy brief outlining opportunities for innovation in the region.

Like all living organisms, crops need access to the right amount of nutrients for optimal growth. Plants get nutrients — like nitrogen, phosphorus, and potassium, in addition to other crucially important micronutrients — from soils and carbon, hydrogen, oxygen from the air and water. When existing soil nutrients are not sufficient to sustain good crop yields, additional nutrients must be added through fertilizers or manures, compost or crop residues. When this is not done, farmers effectively mine the soil of fertility, producing short-term gains, but undermining long-term sustainability.

Nutrient management involves using crop nutrients as efficiently as possible to improve productivity while reducing costs for farmers, and also protecting the environment by limiting greenhouse gas emissions and water quality contamination. The key behind nutrient management is appropriately balancing soil nutrient inputs — which can be enhanced when combined with appropriate soil organic matter management — with crop requirements. When the right quantities are applied at the right times, added nutrients help crops yields flourish. On the other hand, applying too little will limit yield and applying too much can harm the environment, while also compromising farmers’ ability to feed themselves or turn profits from the crops they grow.

Smallholder farmers in South Asia commonly practice poor nutrition management with a heavy reliance on nitrogenous fertilizer and a lack of balanced inputs and micronutrients. Declining soil fertility, improperly designed policy and nutrient management guidelines, and weak fertilizer marketing and distribution problems are among the reasons farmers fail to improve fertility on their farms. This is why it is imperative to support efforts to improve soil organic matter management and foster innovation in the fertilizer industry, and find innovative ways to target farmers, provide extension services and communicate messages on cost-effective and more sustainable strategies for matching high yields with appropriate nutrient management.

Cross-country learning reveals opportunities for improved nutrient management. The policy brief is based on outcomes from a cross-country dialogue facilitated by CSISA earlier this year in Kathmandu. The meeting saw researchers, government and business stakeholders from Bangladesh, India, Nepal, and Sri Lanka discuss challenges and opportunities to improving farmer knowledge and access to sufficient nutrients. Several key outcomes for policy makers and representatives of the agricultural development sector were identified during the workshop, and are included in the brief.

Extension services as an effective way to encourage a more balanced use of fertilizers among smallholder farmers. There is a need to build the capacity of extension to educate smallholders on a plant’s nutritional needs and proper fertilization. It also details how farmers’ needs assessments and human-centered design approaches need to be integrated while developing and delivering nutrient application recommendations and extension materials.

Nutrient subsidies must be reviewed to ensure they balance micro and macro-nutrients. Cross-country learning and evidence sharing on policies and subsidies to promote balanced nutrient application are discussed in the brief, as is the need to balance micro and macro-nutrient subsidies, in addition to the organization of subsidy programs in ways that assure farmers get access the right nutrients when and where they are needed the most. The brief also suggests additional research and evidence are needed to identify ways to assure that farmers’ behavior changes in response to subsidy programs.

Market, policy, and product innovations in the fertilizer industry must be encouraged. It describes the need for blended fertilizer products and programs to support them. A blend is made by mixing two or more fertilizer materials. For example, particles of nitrogen, phosphate and small amounts of secondary nutrients and micronutrients mixed together. Experience with blended products are uneven in the region, and markets for blends are nascent in Bangladesh and Nepal in particular. Cross-country technical support on how to develop blending factories and markets could be leveraged to accelerate blended fertilizer markets and to identify ways to ensure equitable access to these potentially beneficial products for smallholder farmers.

Download the CSISA Policy and Research Note:
Development of Balanced Nutrient Management Innovations in South Asia: Lessons from Bangladesh, India, Nepal, and Sri Lanka.

The CSISA project is led by CIMMYT with partners the International Rice Research Institute (IRRI) and the International Food Policy Research Institute (IFPRI) and funded by the U.S. Agency for International Development and the Bill & Melinda Gates Foundation.

Nurture soil as our food and climate insurance

Written by Jérôme Bossuet on . Posted in Features.

Kassim Massi and Joyce Makawa have learned how conservation agriculture nurtures the soil of their 2.5-acres farm in Lemu, Malawi, and helps them to better cope with regular dry spells and storm rains. With four children and two grandchildren, their livelihoods depend on rainfed crop farming, in particular maize, the main staple in Malawi, and a few goats and free-range poultry. The International Maize and Wheat Improvement Center (CIMMYT) introduced them to conservation agriculture, along with five other families in their community.

“I have learnt a lot from this experiment. I can see that with crop rotation, mulching and intercropping I get bigger and healthier maize cobs. The right maize spacing, one seed at the time planted in a row, creates a good canopy which preserves the soil moisture in addition to the mulch effect,” Massi explains. “The mulch also helps to limit water runoff when there are heavy rains. I don’t see the streams of mud flowing out of this plot like for my other field where I only planted maize as usual on ridges,” he adds.

Massi and Makawa started small, on a quarter acre, testing maize and maize-pigeon pea intercropping under conservation agriculture. Later they diversified to a maize-groundnut rotation with pigeon pea alleys, while introducing different drought-tolerant maize varieties on their plot. Pigeon pea and groundnut are legume crops that enrich the soil in nitrogen via nodules that host specific bacteria called rhizobia in their root systems. Massi and Makawa also put layers of maize stalks and groundnut haulms on the ground after harvest, creating a mulch that not only enriches the soil in organic matter but retains soil moisture and improves soil structure.

While they got only two bags of 50kg maize grain from their conventionally tilled maize field, they harvested almost three times more maize grain plus three bags of groundnuts, and two and half bags of pigeonpea from the 0.1 hectares grown under conservation agriculture. “This plot has become our food insurance and we plan to expand it.”

Family farmers Kassim Massi and Joyce Makawa in Lemu, Malawi. (Photo: Shiela Chikulo/CIMMYT)
Family farmers Kassim Massi and Joyce Makawa in Lemu, Malawi. (Photo: Shiela Chikulo/CIMMYT)

Good for the soil and good for the farmer

“Building healthy soils over the years is one of the great impacts of conservation agriculture,” explains Christian Thierfelder, an agronomist with CIMMYT in Zimbabwe. “With no tillage, legume rotation or intercropping and crop residue management, a beneficial soil pore structure is developed over time. This enables water to infiltrate into the soil where it is available for plant growth in times of drought or during in-season dry spells.”

Under the GIZ-funded Out scaling climate-smart technologies to smallholder farmers in Malawi, Zambia & Zimbabwe initiative, the different ecosystem services that soils bring have been measured against the typical ploughed maize monocropping system. Fifteen year-long experiments show that 48.5mm more water infiltrates per hour under no-till as compared with the conventional method. Soil erosion is reduced by 64% for ripline-seeded maize with legume intercropping. At the Henderson Research station in Zimbabwe where soil erosion loss has been quantified, it means 90 metric tons per hectare of topsoil saved over twelve years.

“Conservation agriculture is good for the soil, and it is good for the farmer. The maize-legume intercropping under conservation agriculture provides very good financial return to labor and investment in most rural communities we worked with,” Thierfelder notes.

Climate mitigation or resilience?

There is growing recognition of the importance of soils in our quest for sustainability.

Soils play for instance an important role in climate regulation. Plants fix carbon dioxide (CO2) through photosynthesis and when those plants die and decompose, the living organisms of the soil, such as bacteria, fungi or earthworms, transform them into organic matter. That way, soils capture huge quantities of the carbon emissions that fuel climate change. This soil organic carbon is also essential for our food security because it retains water, and soil nutrients, essential for growing crops.

The quantity of carbon soils capture depends on the way farmers grow their crops. Conservation agriculture improves soil biodiversity and carbon sequestration by retaining crop residues as mulch, compared to conventional practices.

“Research shows that practices such as conservation agriculture can restore soil organic carbon at the level of four per thousand when farmers apply all principles of conservation agriculture: no-till, soil cover and crop diversification,” explains Marc Corbeels, agronomist seconded to CIMMYT from Cirad. Increasing soil organic content stocks globally by 0.4% per year is the objective of the “4 per 1000” initiative as a way to mitigate climate change and improve food security. At global level, sequestrating 0.4% more soil organic carbon annually combined with stopping deforestation would counteract the annual rise in atmospheric CO2.

“The overall soil organic carbon sequestration potential of conservation agriculture should however not be overestimated,” Corbeels warns. “Carbon sequestration is complex and context-specific. It depends for instance on the type of soils and the initial soil organic status, and the crop and biomass productivity as enough crop residues should be produced.”

“Now farmers in Malawi, Zambia and Zimbabwe are facing prolonged drought and, in some parts, farming communities got hit by flash floods. With degraded and barren soils in this tropical environment, it is a disaster. In my experience, more than mitigation, improved climate resilience is a bigger benefit of conservation agriculture for the farmers”, Corbeels says.

“Science is important to build up solid evidence of the benefits of a healthy soil and push forward much-needed policy interventions to incentivize soil conservation,” Thierfelder states.

Scaling out conservation agriculture practices is what has driven him over the past decade in southern Africa.

“One big lesson I learnt from my years of research with farmers is that if you treat well your soil, your soil will treat you well. Conservation agriculture adopters like Kassim Massi and his family are more resilient to these successive shocks. We need more farmers like them to achieve greater food security and climate resilience in the region,” he concludes.

December 5, we are celebrating World Soil Day under the theme “Stop Soil Erosion, Save our Future!” As CIMMYT’s research shows, farmers cannot deliver sustainable food security without healthy soils, as the farming land producing our staple crops provide important environmental services as well. CIMMYT calls for soil-smart agriculture and food systems.

Researchers visit maize fields in Ethiopia's Wondo Genet Agricultural Research Center. (Photo: Peter Lowe/CIMMYT)

New tools guide interventions against acid soils in Africa using lime

Written by Jérôme Bossuet on . Posted in Blogs.

Researchers visit maize fields in Ethiopia's Wondo Genet Agricultural Research Center. (Photo: Peter Lowe/CIMMYT)
Researchers visit maize fields in Ethiopia’s Wondo Genet Agricultural Research Center. (Photo: Peter Lowe/CIMMYT)

One major reason why maize productivity in sub-Saharan Africa is very low is poor soil health. Soil acidity is often mentioned because of its impact on crop yields and the extent of acid soils in the region. A recent soil mapping exercise, conducted by the Ethiopian Soil Information System (EthioSIS) under the administration of the Ethiopian Agricultural Transformation Agency (ATA), estimated that 43% of arable lands were affected by acid soils and that 3.6 million people, about 10% of the total rural population, live in areas with acidic soils.

Very acid soils — those with a pH below 5.5, roughly one hundred times more acidic than neutral soils — are associated with certain toxicities, like aluminum and iron excess, and some nutrient deficiencies. Soil acidity pushes soil nutrients out of reach of the plant, leading to stunting of root system and plant. As a result, the plant becomes also less tolerant to drought.

Soil acidification depends on soil nature, agroecology and farming systems. It happens through natural leaching of CO2 after rainfall and excess application of nitrogenous fertilizer or organic matter, for instance.

As a result, soil acidity significantly affects maize yields. In Ethiopia, studies have revealed substantial impacts on crop productivity related to acid soils and the importance of acid soil management for Ethiopia’s food security. The Ethiopian Institute of Agricultural Research (EIAR) estimated that soil acidity on wheat production alone costed the country over 9 billion Ethiopian Birr, about $300 million per year.

Acidic soils in the limelight

Preliminary analysis led by the International Food Policy Research Institute (IFPRI) suggests that yields of major cereal crops, such as wheat and barley, could increase by 20 to 40% with the application of lime in acidic areas of the country.

While these preliminary results are significant, we need to know more about local farmers’ experience with acidic soil and their mitigation strategies. Such impact assessments are however typically determined at either the national or experimental plot level and do not map where mitigating against acid soils would be the most profitable.

To improve acid soils, farmers may apply lime on their fields to raise the pH, a practice known as liming. How much lime to apply will depend on the crop, soil type but also on the quality of lime available. Liming has multiple beneficial effects like improving nitrogen fixation of legume nodules, boosting yields of legume crops.

But liming has a cost. It can quickly become a very bulky affair as we need to apply 3 to 4 tons per hectare for sandy soils and up to 8 tons per hectare for clay and humifere soils.

Furthermore, existing lime markets are quite limited or even non-existent in many areas, even those where acidic soils are prevalent. Developing supply chains from scratch is difficult and costly. Understanding the costs and potential returns to such investments is important. There are many questions to ask at different levels, from the farm and farming system to the lime supply chain. What are the available lime sources — calcitic, dolomite or blend — and lime quality? Where are the lime processing units and how could you assess the transport cost to the farms? What could be the crop yield response depending on the lime application?

User-friendly and scalable dashboard

IFPRI, in collaboration with EIAR, the International Maize and Wheat Improvement Center (CIMMYT) and the German aid agency GIZ, developed a pilot in Ethiopia’s Amhara region to help better target lime interventions for a greater impact. Amhara region was chosen because of the importance of acid soils, and access to extensive soil data.

Combination of several spatial datasets on soil quality, agroecological, weather, long-term agronomic trials and crop modelling tools enabled to generate at scale, georeferenced estimates of crop yield responses for different lime applications. Calibration of this spatial model for wheat estimated a yield increase of approximately 30% increasing the pH from 5.5 to 6.5, which is relatively consistent with general research data and expert opinion.

Mapped estimates of the grain prices and the delivered costs of lime, based on the location of the lime crushers in the region and transport costs, enables then to map out the spatial profitability of lime operations.

Initial calculations revealed a great variability of lime costs at the farmgate, with transportation representing at least half of total lime costs. It showed also that farmers often do not use the most cost-effective combination of inputs to tackle soil acidity.

Another possible application is to determine maize growing areas where lime benefits outweigh the costs, which would be ideal sites for demonstrating to farmers the positive impact lime applications could have to their livelihoods.

This Amhara lime dashboard prototype demonstrated its scalability. A national dashboard is currently being developed, which includes lime sources GPS location, grain prices and district-level soil quality mapping. This approach is tested also in Tanzania.

CIMMYT and its partners plan to package such tool in a user-friendly open-access web version that can be rapidly updated and customized depending on the area of intervention, for instance integrating a new lime source, and applied for different crops, and across the Eastern African region. Such dashboards will help development organizations and government make better informed decisions regarding lime investments.

A multi-crop, multi-use zero-tillage seeder at work on a conservation agriculture trial plot, left, at CIMMYT's headquarters in Texcoco, Mexico. The residues retained on the soil surface and the permanent raised beds are in clear contrast with the conventional plot on the right. (Photo: CIMMYT)

Scientists propose a low-cost, reliable system to measure soil organic carbon

Written by Alison Doody on . Posted in News.

A multi-crop, multi-use zero-tillage seeder at work on a conservation agriculture trial plot, left, at CIMMYT's headquarters in Texcoco, Mexico. The residues retained on the soil surface and the permanent raised beds are in clear contrast with the conventional plot on the right. (Photo: CIMMYT)
A multi-crop, multi-use zero-tillage seeder at work on a conservation agriculture trial plot, left, at CIMMYT’s headquarters in Texcoco, Mexico. The residues retained on the soil surface and the permanent raised beds are in clear contrast with the conventional plot on the right. (Photo: CIMMYT)

New research by an international team of scientists, including International Maize and Wheat Improvement Center (CIMMYT) Director for the Integrated Development Program, Bram Govaerts, outlines a proposed accounting system for organic carbon in soils that could encourage farmers to adopt better land management practices and increase levels of organic carbon in their soil.

Reported this month in the journal Carbon Management, the study highlights how increasing soil organic carbon (SOC) would build agricultural resilience and fertility and reduce greenhouse gas emissions — but we need to be able to measure it.

Soil is a huge carbon reservoir — in fact, soils contain one of the largest organic carbon stocks on the planet. With proper land management, soils have the potential to store even more. Improved SOC levels have also been connected with improved soil quality, reduced susceptibility to erosion and greater agricultural yields and yield stability, particularly under drought. This makes them a crucial player in climate change mitigation and agricultural resilience.

Policy makers and environmental groups are becoming increasingly interested in soil health and its effect on climate change. The 4 per 1000 initiative, launched at the COP 21 climate talks in Paris in 2015, argues that an annual growth rate of 0.4% in soil carbon stocks would significantly reduce human activity-related CO2 concentrations in the atmosphere. The most recent Intergovernmental Panel on Climate Change (IPCC) assessment highlights carbon sequestration as one of the options, alongside massive fossil fuel reduction, to keep warming below 2 degrees Celsius, in accordance with the Paris Climate Agreement.

Increasing organic carbon content in soils also has another very important function: crop nutrition. Last year, researchers from CIMMYT and the Nature Conservancy found that wheat grown on soils rich in organic matter had more essential nutrients like zinc and protein.

However, increasing levels of organic carbon in the soil can be costly in the short term, so farmers need to see improvements in the performance of their soils as a result of their efforts.

Quantifying soil carbon

That’s where a global soil information system comes in. By integrating empirical models, expanded measurement and monitoring networks, remote sensing and crowdsourced management data, SOC stocks can be assessed efficiently and reliably. Farmers and policy makers would get a clear picture of how much soil organic carbon is increasing and at what rate.

The global soil information system would work by pulling different sources of existing information together to provide a comprehensive account of soil organic carbon stocks worldwide.

As SOC content can vary over time, an important component of the system would involve using monitoring networks at precise locations which can then be resampled regularly. Alongside this information, empirical models would be used to predict SOC changes based on already observed results from lab- and field-based experiments, and to predict the impacts of different soil and climate conditions. Remote sensing data can provide information on land cover, crop species and land management practices at a very low cost, to supplement and verify management activity data reported by land users.

The international team of scientists pointed out that greater coordination and transparency among scientists, remote sensing specialists and land managers is crucial to the success of a global soil information system.

Incentivizing carbon sequestration among land managers is no mean task. The authors argue that existing approaches like direct compensation to farmers for CO2 removal and storage, government subsidies such as the European Union’s Common Agricultural Policy (CAP) and the option of earning a premium price for producing sustainable agricultural products, need a reliable carbon accounting system to ensure their success. A global soil information system might just hold the key.

Read the full article:
“Quantifying carbon for agricultural soil management: from the current status toward a global soil information system” in Carbon Management, DOI: 10.1080/17583004.2019.1633231

This study was made possible through the support provided by the TomKat Foundation. Additional support was provided by the NASA Harvest Consortium (www.nasaharvest.org), a multi-disciplinary program that empowers informed agricultural decisions through the use of Earth observations.

The itsy bitsy spider can make a big impact in agriculture

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Face of an adult male Phidippus audax male jumping spider. (Photo: Opoterser/Wikimedia Commons)
Face of an adult male Phidippus audax male jumping spider. (Photo: Opoterser/Wikimedia Commons)

A new study explores how conservation agriculture in southern Africa supports spider populations and diversity in fields, which could help mitigate pest damage and potentially lead to higher yields for farmers. According to the Food and Agriculture Organization of the United Nations (FAO), herbivorous insects such as aphids, caterpillars and weevils destroy about one fifth of the world’s total crop production each year. Spiders can help keep voracious pests in-check, but conventional farming practices (e.g. tilling, crop residue removal and monoculture) can harm or drastically reduce these beneficial bio-control agents.

There are more than 45,000 identified spider species around the world. From glaciers to tropical rainforests, they inhabit every terrestrial ecosystem on earth. Some can even live in tidal zones, and at least one species inhabits fresh water. While we tend to associate spiders with webs, only about 50 percent of the species catch their prey this way; the rest hunt on plants, on the ground or below it, using a variety of tactics such as stalking, stabbing, crushing – even seduction.

Although spiders have been around for 300 million years, some species are at risk of extinction due to habitat loss and fragmentation. Drastic reductions in vegetation – whether from a new parking lot or a tilled field – removes the food source that attracts their prey. Bare ground exposes their nesting sites and themselves, which makes it harder to hunt and easier to be hunted by birds and small mammals.

At the Chinhoyi University of Technology experimental farm in Zimbabwe, a team of researchers aimed to determine the response of spiders under different agricultural practices. Conventional farmers often prepare their fields for planting by physically breaking up and inverting the top 6-10 inches of soil. This practice of ploughing prepares a fine soil tilth, which makes it easier to plant; it breaks up and buries weeds, and reduces soil compaction to aerate the soil. But tilling also increases topsoil erosion from wind and water. It accelerates soil carbon decomposition, reduces soil water infiltration and disrupts microorganisms living in the soil, including beneficial insects and spiders.

The researchers conducted two experiments over the 2013/2014 and 2014/2015 cropping seasons to see how tilling, crop residue retention (i.e. leaving stalks and post-harvest organic matter in the field), fertilizer application and weeding affected ground- and plant-wandering spider species. They hypothesized that spider abundance and diversity would increase with lower levels of soil disturbance and more plant cover.

The results showed direct seeding into no-till soil increased the abundance of spiders and the diversity of species. Mulching also showed a positive effect. Contrary to their hypotheses and results from temperate regions, the application of fertilizer and intense weeding did not affect the spider community. The researchers attributed this to the difference in climatic conditions (tropical vs. temperate) of this study in southern Africa.

“Often the government’s and farmer’s immediate reaction to a crop pest issue is to apply a pesticide, but we can make use of biological control agents, which may be cheaper and less damaging for the environment,” says Christian Thierfelder, a co-author of the study. Thierfelder is a cropping systems agronomist and conservation agriculture specialist with the International Maize and Wheat Improvement Center (CIMMYT) with long-term experience in sustainable intensification.

“Spiders, ants and beetles all do a really good job with little or no cost to the farmer,” he adds. “For us, it’s quite fascinating to see simple agronomic practices to affect and control crop pests. This also provides new avenues of dealing with the fall armyworm, an invasive species which has devastated crops across the majority of sub-Saharan Africa countries.”

A robust number of studies from Europe, Australia and North America have shown the link between conservation agriculture and biodiversity, but Thierfelder says that research on biodiversity in agronomic systems is relatively new in southern Africa. While the study in Zimbabwe helps fill this gap, more research is needed to show the connection between the abundance of spiders, beetles and ants with the suppression of insect pest activity.

For more information, read Spider community shift in response to farming practices in a sub-humid agroecosystem in southern Africa.

This research was jointly funded by Chinhoyi University of Technology (CUT) and the German Academic Exchange Program (DAAD). The CGIAR Research Program on Maize (MAIZE) supported this study through Christian Thierfelder’s contributions.

Majola Mabuza, Program Officer, The Southern African Confederation of Agricultural Unions. (Photo: UNFCCC)

SACAU’s Majola Mabuza at COP24: How soil can help meet climate targets

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Majola Mabuza, Program Officer, The Southern African Confederation of Agricultural Unions. (Video: UNFCCC)

KATOWICE, Poland (CIMMYT) — Agricultural scientists attending U.N. COP24 climate talks in Katowice, Poland are discussing a wide range of potential solutions to slow global warming and meet targets laid out in the Paris Agreement on climate change.

The agreement, which has been under intense discussion by negotiators, requires keeping global temperatures in check — to no more than 1.5 degrees Celsius above pre-industrial levels.

Delegates participating in a side event session on agriculture, which produces about a third of global greenhouse gas emissions, discussed the role of soil, presenting scientific evidence of the value of recarbonization. Much of the carbon that was formerly stored in soil, which acts as a carbon sink, has been released into the atmosphere, contributing to global temperature increases.

Majola Mabuza, program officer responsible for policy at the non-profit Southern African Confederation of Agricultural Unions (SACAU), participated in the panel on Monday evening and discussed various risks farmers face and hurdles that need to be overcome.

Mabuza, an agricultural economist, whose research interests span institutional economics of farmers’ organizations, food security and the economics of non-conventional agricultural enterprises, shared some views with CIMMYT about recarbonization.

Q: What is the scale of the role soil plays in climate change?

A: The global carbon pool in soils — at a depth of 2 meters — is three times that of carbon found in the atmosphere. As such, both increases in soil organic carbon and protection against losses from this pool are important strategies for environmental protection. Management practices that raise soil organic carbon have co-benefits such as increased productivity and resilience and can in turn improve food security and sustainable rural development.

Land use changes such as intensification of agriculture or converting grasslands into plow lands often turn them into carbon sources, releasing huge amount of carbon into the atmosphere. The time scales of the source and sink function of soils are fundamentally different: whereas building up belowground carbon stocks takes hundreds or thousands of years, depleting these stocks can be measured in decades or even days, [for example in the case of] forest or grassland fires.

Q: Will soil be the silver bullet to meet food security and climate change goals?

A: Not necessarily a silver bullet. To address climate change and improve food security, a lot is required from various actors. For instance, at this conference, we have learned of food that is produced, but almost a third of it is lost or goes to waste along the chain. Lost or wasted food also contributes to emissions in various forms. So, fixing the issue of soils alone will not win the battle, a lot more issues need to be fixed.

At the production stage, soils have an important role to play in reducing carbon emissions. Soil acts as a sink for carbon, the greenhouse gases that contribute to global warming. Agricultural management approaches such as conservation agriculture and agroforestry simultaneously improve soil carbon, soil fertility and water conservation. More food will be produced on the same land to meet the needs of the growing population.

Q: What will you speak about at the COP24 side event Soils Advantage: Transforming Agriculture by Recarbonizing the Earth’s Soil?

A: Farmers are essentially the managers of land and soils and are by far responsible for whatever happens to the soil. Are farmers, including smallholders, aware of the connection between soil activities and climate change? Do they know the carbon content in their farms? What incentives are there for farmers to build soil organic carbon within their farm plans? What lessons have we learnt with the promotion of such programs as organic farming, conservation agriculture and/or climate-smart agriculture that we can tag along in the drive to transform agriculture by recarbonizing the soil? While some advocate for rewarding better practices or performance on soil carbon in financial markets by attracting higher land values, lower interest rates on loans, or lower insurance premiums, how practical will this be in developing countries where most smallholders do not own the land they produce from?

Q: What is the purpose of recarbonizing?

A: The purpose is essentially to take carbon back to the soil. A lot of human activities, including deforestation, repeated soil tillage — industrial agriculture — and burning of fossil fuels have disrupted the carbon cycle, taking it out of balance. Too much of the carbon that was once in the soil has been released to the atmosphere, hence a lot of it is now in the atmosphere and some in the ocean, but not enough where it once was and where it is more beneficial for sustainable food production and food security — in soil.

Q: How is recarbonization achieved?

A: The most feasible route is to cover the soil with plants and trees, promote organic farming, conservation agriculture, agroforestry, and climate-smart agriculture practices. Plant photosynthesis has the remarkable ability to capture atmospheric CO2, release the oxygen back into the atmosphere, and convert the carbon into sugars, which are used by plants for growth. A considerable proportion of the captured CO2 is released through the plant’s roots to feed soil microorganisms, which in turn assist the plant in acquiring nutrients. Soil microorganisms use this energy to make soil carbon and humus. If left undisturbed, soil humus can lock carbon into place for an average lifetime of hundreds to thousands of years.

Q: Are there efforts underway to do this?

A: Current programs include organic farming, conservation agriculture and climate-smart agriculture.

Q: In terms of wheat and maize, will this have an impact? 

A: A great impact. Maize and wheat are the main staples for the poor in Africa and Asia respectively. If we build our soil recarbonizing program around such staple crops.

Q: What is the impact of crop rotations on soil?

A: Crop rotation is an important practice of any sustainable agricultural system. Crop rotation has the following major benefits: It improves soil fertility — as legumes such as groundnuts and beans fix nitrogen in the soil for the benefit of cereals such as maize. Farmers use less chemical fertilizer because legumes in the soil fix the nitrogen naturally. It helps to reduce weeds, diseases and pests by breaking their lifecycles as crops are rotated. It reduces the risk of crop failure in case of drought or disease and improves crop yield.

Soils Advantage: Transforming Agriculture by Recarbonizing the Earth’s Soil was held on Dec. 11, 2018 at 6:30-9:00 p.m. in the Bieszczady side event room in section G at the COP24 venue.

If we take care of our soils, our soils will take care of us. (Photo: Shashish Maharjan/CIMMYT)

Gratitude for soil

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If we take care of our soils, our soils will take care of us. (Photo: Shashish Maharjan/CIMMYT)
If we take care of our soils, our soils will take care of us. (Photo: Shashish Maharjan/CIMMYT)

On December 5, we celebrate World Soil Day. This year the theme is “Be the solution to soil pollution.” Most of you may not have been aware that such a day even existed or perhaps even question the reason why the world even dedicates an entire day to celebrate soil. The authors of this article are soil scientists; we have devoted our professional careers to studying soil. Perhaps we are biased, but we use this opportunity to enlighten readers with a greater appreciation for the importance of this thin layer of our planet we call soil.

Humankind has a conflicting relationship with soil. In English, “dirt” and “dirty” are synonyms for unclean, calling a man or a woman “dirty” is a terrible insult. A baby’s dirty diapers are said to be “soiled.” But if we dig deeper into human consciousness, we find a different story.

For Hindus, the Panchtatva defines the universal laws of life. Everything, including life, is composed of five basic elements: Akash, space or sky; Vayu, air; Jal, water; Agni, fire; and Prithvi, earth or soil. In the Judeo-Christian tradition, the first two human beings on the planet were Adam and Eve. In Hebrew, the original language of the Bible’s Old Testament, the name Adam means “earth” or “soil” and Eve means “life.” These images and symbols portray that human life originally derived from soil.

It gets even deeper: The English terms “human” and “humanity” are rooted in the Greek word “humus,” the fertile black topsoil.

When we use the words “soil” and “dirt” as derogatory terms, we literally define ourselves as soil. Soil is important and here are a few reasons why.

Soil is absolutely critical for the survival of our species and of all living life on the planet. Over 90 percent of all food produced in the world comes from soil and a greater percentage of the world’s freshwater passes through soil.

Arguably, climate change is the greatest threat to our species. Despite mitigation efforts by the global community, soil is frequently forgotten. However, soil holds roughly two and a half times the amount of carbon held in the atmosphere and in all of the plants and animals combined.

Soil is also the greatest reservoir of biodiversity on the planet. In one pinch of soil, there are over 1 billion individual organisms and 1 million unique species, most of which we know almost nothing about. In one handful of soil, there are more living organisms than the total number of human beings that have ever walked on the planet. As all of our antibiotics have been derived from soil microorganisms, the secrets to fighting all kinds of diseases are just under your feet.

In Nepal, soil is deeply interrelated with culture. From birth to death, Nepalese use soil in many rituals: naming ceremonies, birthday celebrations, soiling on Ashar 15, local healing and medicine, etc.

The government of Nepal has set ambitious targets for increasing the levels of organic matter in soil. This is essential to ensure that the soils that have sustained Nepali civilization for centuries will continue to sustain future generations. We need to encourage farmers and land managers in Nepal to maintain terracing on steeply sloped lands to protect against soil erosion. It is also important to appropriately use agrochemicals, such as pesticides and inorganic fertilizers, to improve soil health and crop productivity.

Soil has been polluted by heavy metals, effluents from chemical industries, indiscriminate use of agrochemicals, urbanization without proper planning, networking of roads without considering the carrying capacity of the soil and other factors. So let’s not overlook the importance of soil. We need to value the cleansing properties of soil, particularly riverine soils, and prevent these areas from continuing as the dumping grounds and sewers of Kathmandu and other cities.

On this day, the day when we celebrate soil, take a moment to look under your feet and marvel at the beauty and complexity of soil.

If we take care of our soils, our soils will take care of us.