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Tag: agroecology

In sub-Saharan Africa, mineral fertilization and agroecology are not incompatible

Written by Julian Bañuelos-Uribe on . Posted in Press releases.

Are agroecological approaches, based for example on the use of legumes and manure, enough by themselves to ensure a long-term increase in annual crop yields in sub-Saharan Africa (SSA), without using more mineral fertilizer?

The answer is no, according to a team of agronomists who have published an in-depth analysis of 150 scientific articles on annual crops (maize, sorghum, millet, rice, cassava, etc.) and tropical legumes, both annual grain legumes (cowpea, groundnut) and legume trees (acacia, sesbania) in tropical environments.

These publications collate 50 years of knowledge on nutrient balances in sub-Saharan Africa, biological nitrogen fixation by tropical legumes, manure use in smallholder farming systems and the environmental impact of mineral fertilizer.

“When we look at comparable climate conditions and physical soil constraints, yields of maize – the main source of calories for people – in sub-Saharan Africa are three to four times lower than elsewhere in the world. This is largely due to the fact that mineral fertilizer use (nitrogen, potassium) is on average four times lower there”, says Gatien Falconnier, a researcher at CIRAD based in Zimbabwe and lead author of the article. “On average, 13 kg of nitrogen are used per hectare and per year in sub-Saharan Africa, for all crops, bearing in mind that the poorest farmers have no access to nitrogen fertilizers and therefore do not use them. It is mainly agri-business and vegetable farmers that have access to fertilizers”, adds François Affholder, an agronomist at CIRAD based in Mozambique and co-author of the article.

Maize and cowpea intercropping in the Maravire field. (Photo: CIMMYT)

“Our objective is not to produce like Europe or North America, but to produce more and more regularly according to the seasons and the years, and thus to increase the economic sustainability of our farming systems. To do so, we must ensure a minimum level of nutrients for crops, which require essential mineral elements for efficient photosynthesis, and therefore growth. Soils are typically lacking in mineral elements in sub-Saharan Africa, and the largely insufficient organic inputs lead to nutrient deficiencies in crops. This is the main limiting factor for crop yields, excluding drought situations”, says Pauline Chivenge of the African Plant Nutrition Institute (APNI). “The work by Christian Pieri showed as early as 1989 that it is possible to restore high levels of fertility to African soils through a balanced approach to organic and mineral nutrient inputs”, says François Affholder.

The article highlights five reasons why more mineral fertilizer is needed in sub-Saharan Africa:

  1. Farming systems are characterized by very low mineral fertilizer use, widespread mixed crop-livestock systems, and significant crop diversity, including legumes. Inputs of mineral elements to crops by farmers are insufficient, resulting in a widespread decline in soil fertility due to soil nutrient mining.
  2. The nitrogen requirements of crops cannot be met solely through biological nitrogen fixation by legumes and manure recycling. Legumes can only fix atmospheric nitrogen if symbiosis with soil bacteria functions correctly, which requires absorption of different mineral elements by the plant. Ken Giller of Wageningen University highlights that the ability of legumes to capture nitrogen from the air through their symbiosis with rhizobium bacteria is a fantastic opportunity for smallholder farmers, “but the amounts on nitrogen fixed are very small unless other nutrients such as phosphorus are supplied through fertilizers”.
  3. Phosphorus and potassium are often the main limiting factors of the functioning of plants and living organisms, including symbiotic bacteria: if there is not enough phosphorus and potassium in soils, then there is no nitrogen fixation. These nutrient elements, phosphorus, potassium and micro-elements, need to be provided by fertilizers, since they cannot be provided by legumes, which draw these elements directly from the soil. In the case of manure, this is simply a transfer from grazing areas to cultivated areas, which gradually reduces fertility in grazing areas.
  4. If used appropriately, mineral fertilizers have little impact on the environment. The greenhouse gas emissions linked to nitrogen fertilizer use can be controlled through a balanced and efficient application. In addition, mineral fertilizers can be produced more efficiently in order to reduce the impact of their production on greenhouse gas emissions, keeping in mind that this impact is low, at around 1% of total anthropogenic emissions.
  5. Further reducing mineral fertilizer use in SSA would hamper productivity gains and would contribute directly to increasing food insecurity and indirectly to agricultural expansion and deforestation. Producing for a population that will double by 2050 is likely to require the use of more agricultural land. An extensive strategy thus harms biodiversity and contributes to increasing greenhouse gas emissions, contrary to an agroecological intensification strategy combined with efficient and moderate mineral fertilizer use.

“If we take account of biophysical production factors, such as climate and soil, and shortages of land and agricultural workers, it will be impossible to reach a satisfactory production level by fertilizing soils only with manure and using legumes”, says Leonard Rusinamhodzi, an agricultural researcher at the Ghana International Institute of Tropical Agriculture.

However, “agroecological principles linked directly to improving soil fertility, such as recycling of mineral and organic elements, crop efficiency and diversity, with for example agroforestry practices and cereal-legume intercropping, remain essential to improve soil health. Soil fertility is based on its organic matter content, provided by plant growth that determines the biomass that is returned to the soil in the form of roots and plant residues. Efficient mineral fertilizer use starts a virtuous circle. These nutrients are crucial for the sustainability of agricultural productivity”, says Gatien Falconnier.

The researchers therefore argue for a nuanced position that recognizes the need to increase mineral fertilizer use in sub-Saharan Africa, in a moderate manner based on efficient practices, in conjunction with the use of agroecological practices and appropriate policy support. This balanced approach is aimed at ensuring long-term food security while preserving ecosystems and preventing soil degradation.

Référence
Falconnier, G. N., Cardinael, R., Corbeels, M., Baudron, F., Chivenge, P., Couëdel, A., Ripoche, A., Affholder, F., Naudin, K., Benaillon, E., Rusinamhodzi, L., Leroux, L., Vanlauwe, B., & Giller, K. E. (2023).

The input reduction principle of agroecology is wrong when it comes to mineral fertilizer use in sub-Saharan Africa. Outlook on Agriculture, 0(0). https://doi.org/10.1177/00307270231199795

*CIRAD, CIMMYT, International Institute of Tropical Agriculture (IITA), Wageningen University and the African Plant Nutrition Institute (APNI)

Contact: presse@cirad.fr

Scientists: 

Gatien Falconnier
gatien.falconnier@cirad.fr

Pauline Chivenge
P.CHIVENGE@apni.net

Leonard Rusinamhodzi
L.Rusinamhodzi@cgiar.org

LIPS-Zim empowers smallholder farmers

Written by mcallejas on . Posted in In the media.

The Livestock Production Systems in Zimbabwe (LIPS-Zim) project implemented by CIMMYT and various research institutions in partnership with the government expects to increase incomes and ensure food security for more than 50,000 rural Zimbabweans.

Read the full story.

 

Farmers in Zimbabwe embrace agroecology

Written by Tawanda Hove on . Posted in News.

Smallholder farmers display a range of small and large grains at the agroecology seed fair in Mbire, Zimbabwe. (Photo: Tawanda Hove/CIMMYT)

Smallholder farmers in resource-poor communities of Zimbabwe and much of the Global South have been experiencing low crop productivity due to many factors, including inappropriate seeds and seed varieties, labor shortages, loss of agro-biodiversity, insufficient inputs, degrading soils, and recurrent droughts. These threats are now amplified by climate change.

This has resulted in broken food systems rendering food and nutrition insecurity commonplace. The One CGIAR initiative, Transformational Agroecology Across Food, Land, and Water Systems, led by the International Maize and Wheat Improvement Center (CIMMYT) in Zimbabwe, is designed to bring agroecological advances to smallholder famers in an effort to strengthen local food systems.

Smallholder farmers in the Mbire and Murehwa Districts of Zimbabwe were introduced to innovative agroecology interventions, premised on harnessing nature’s goods and services while minimizing adverse environmental impacts and improving farmer-consumer connectivity, knowledge co-creation, and inclusive relationships among food system actors.

Smallholder farmers register for the agroecology seed fair in Mbire, Zimbabwe. (Photo: Tawanda Hove)

Farmer to farmer collaboration at seed fairs

In response to challenges related to lack of appropriate seeds and eroding agrobiodiversity and, as a way to transition prevailing food systems to more sustainable ones, farmers were invited to take part in seed fairs. The seed fair’s objective was to enable smallholder farmers to access improved and locally adapted seeds of food crops originating from the private sector and fellow farmers. In addition, the seed fairs provided a platform for learning about agroecological practices. Farmers were also given a chance to see different machinery that could aid in land, food, and feed preparation, and address their labor shortage challenges.

At the opening of the seed fair in Mbire, Dorcas Matangi, CIMMYT research associate, acknowledged that smallholder farmers operate in challenging and complex ecological, social, and economic systems and there is a need for interventions that address the natural resource base without ignoring the social and economic dynamics within communities.

“The communal culture of sharing and trading between community members can be capitalized on for a collective benefit, said Matangi. “One such case is through events such as seed fairs where we encourage farmers to showcase and sell seeds they know perform very well.”

She further explained to the participating farmers how increasing their crop diversity and using practices such as conservation agriculture techniques benefit the environment and improves food security and nutrition.

“I am grateful for these efforts,” said Grace Musandaira, supervisor of the Agriculture Advisory and Rural Development Service. “Our region is arid, and as such, it is very difficult for our farmers to achieve significant yields to assure them there is enough food for the year. In addition, the knowledge provision relating to preserving and improving agrobiodiversity through agroecological practices is set to improve rural livelihoods.”

Senzeni Nyagonye, a farmer in Mbire, said “This initiative is teaching and exposing us to so many new concepts such as conservation agriculture with mechanization. If we can apply conservation agriculture with the seeds we bought at this seed fair, we are optimistic about a great harvest.”

A total of 1,058 farmers attended two seed fairs in Mbire and Murehwa. Farmers had the opportunity to access a variety of crop seeds ranging from maize, to sorghum, millets, groundnuts, bambara groundnuts, and sunflowers. More than 200 farmers exhibited local seeds that were available for sale or exchange. Private seed companies also showcased and sold certified drought-tolerant maize, sorghum, bean and cowpea varieties.

“The seed fairs in Mbire and Murehwa were very successful”, said Matangi. “And we feel these efforts will serve as a useful case study to guide a national scale-up.”

Using ENM principles to preserve soil health

Written by Sarah McLaughlin on . Posted in Publications.

In a new Frontiers publication, scientists from the International Maize and Wheat Improvement Center (CIMMYT) outline how to achieve an ecologically based approach to sustainable management of soil fertility, particularly for smallholders.

What is ecological nutrient management (ENM)?

Across the globe, smallholder farming communities only have limited resources to improve their financial and food security, and soil degradation is common. Ecological nutrient management (ENM), an agroecological approach to managing the biogeochemical cycles that regulate soil ecosystem services and soil fertility, can prevent degradation and preserve soil health.

Five principles guide ENM strategies:

  • Building soil organic matter and other nutrient reserves.
  • Minimizing the size of nitrogen (N) and phosphorus (P) pools that are most vulnerable to loss.
  • Maximize agroecosystem capacity to use soluble, inorganic N and P.
  • Use functional biodiversity to maximize presence of growing plants, biologically fix nitrogen and access sparingly soluble phosphorus.
  • Construct agroecosystem and field scale mass balances to track net nutrient flows over multiple growing seasons.
At the ICRISAT headquarters in Patencheru, India, M.L. Jat and Sieg Snapp stand in front on pigeonpea (Cajanus cajan) varieties, a semi-perennial legume that fixes nitrogen and solubilizes phosphorus for greater nutrient efficiency while building soil health. (Photo: Alison Laing/CSIRO)

Using functionally designed polycultures, diversified rotations, reduced fallow periods, increased reliance on legumes, integrated crop-livestock production, and use of a variety of soil amendments exemplify how ENM works in practice. A key principle is to underpin agroecosystem resilience through the promotion of soil organic matter accrual and restoration of soil function.

Strategic increases of spatial and temporal plant species diversity are used, that meet farmer requirements. This often involves perennial or semi-perennial bushes and vines that provide food, fuel and fodder while restoring soil fertility. ENM long-term management systems can increase yields, yield stability, profitability, and food security, thus addressing a range of smallholder needs.

Read the study: Advancing the science and practice of ecological nutrient management for smallholder farmers

Cover photo: A maize-bean intercrop that exemplifies the ENM approach, taken at CIMMYT’s Chiapas Hub, a long-term field experiment. (Photo: Sieg Snapp/CIMMYT)

Sieglinde Snapp Sieglinde Snapp

Sieglinde Snapp

Written by Rodrigo Ordóñez on . Posted in Uncategorized.

Sieg Snapp is the director of the Sustainable Agrifood Systems program at CIMMYT, which brings together global agricultural economics, systems analysis on agrifood innovations and agricultural systems for development in Africa, Asia and Latin America.

As a Professor of Soils and Cropping Systems Ecology at Michigan State University and Associate Director of the Center for Global Change and Earth Observations, she led research on sustainable farming, particularly for cereal-based, rainfed systems in Africa and North America.

Snapp first partnered with CIMMYT in 1993, when she developed the “mother and baby” trial design. This go-to tool for participatory research has developed farmer-approved technologies in 30 countries.

Snapp has partnered with local and international scientists to tackle sustainable development goals, improve livelihoods and farm sustainably. Her two hundred publications and text books address co-learning, ecological intensification and open data to generate relevant science.