Fertilizer and soil health for enhanced productivity and sustainability in sub-Saharan Africa

Understanding soil health and its key indicators

Healthy soil is the prerequisite to growing nutritious and plentiful crops, which humans require for growth and health. Moreover, healthy soil sustains a diverse community of soil organisms that play important roles in nutrient cycling and maintaining or building soil structure. As such, soil health is essential for human and environmental health and thus deserves our attention on a global and local level.

Assessing soil health requires the evaluation of various physical, chemical, and biological indicators. Physical indicators encompass texture and porosity, while chemical indicators look at nutrient levels and pH, and biological indicators at the diversity of soil organisms. Together, these factors provide insights into soil fertility and functionality and guide management practices to optimize soil health and agricultural productivity.

Addressing critical challenges to improve soil health

• Fertilizer use and crop productivity have increased but progress is too slow

Despite recognising the importance of fertilizers to achieve food security, progress in their adoption has been slow in many regions, especially sub-Saharan Africa. Efforts to boost agricultural productivity through increased fertilizer use have not kept pace with the region’s population growth. Fertilizer application rates are still far from the recommended levels, hindering efforts to enhance crop yields while alleviating poverty.

• From focussing on increasing crop yields to recognising soil health as a prerequisite for sustainability

To increase crop yields in sub-Saharan Africa, many used to focus on inputs like fertilizers while overlooking the foundational role of soil health. However, recognizing the intrinsic link between soil fertility and sustainable agriculture led to paradigm shifts towards Integrated Soil Fertility Management. This holistic management approach integrates organic and mineral inputs to restore soil fertility, enhance crop productivity, and ensure long-term sustainability.

• Fertilizer and soil health – friends or foes?

Fertilizer application is essential to replenish soil nutrients and thus enhance crop yields. However, using fertilizers without considering soil health can harm the environment and lower long-term productivity. Balancing fertilizer application and soil health requires strategic management practices that prioritize nutrient efficiency, organic matter restoration, and ecosystem resilience.

• Limitations to increasing soil organic carbon

Increasing the organic content of soil is pivotal for soil health and nutritious crops. Yet, practical limitations exist, especially in agricultural contexts. Restoring soil organic carbon faces constraints such as land use history, climate variability, and the inherent capacity of soils to sequester carbon. Despite efforts to enhance soil organic carbon through agricultural practices, achieving levels comparable to natural ecosystems remains challenging.

• Economic realities

Even though knowingly critical for increasing crop yields, adopting fertilizers in sub-Saharan Africa is hindered by complex economic factors. Socioeconomic disparities and uncertainties in agricultural production influence farmers’ decisions regarding fertilizer use.

Solutions and needed actions to improve soil health on a global and regional level

• Consensus on what constitutes soil health, based on specific functions and environments

A key performance indicator framework is required to define soil health and the key functions of a healthy soil for the intended land use. Such indicators need to be measurable and interpretable.

• Monitoring schemes to assess progress and support soil health management

National or regional monitoring schemes should support public investments in soil health by monitoring change over time and space. Such soil information should be widely available, also improving digital soil information resources.

• Raising awareness on how farmers and society benefit from improved soil health

Soil health, as a public good, benefits society as a whole as it provides numerous ecosystem services. Hence, investing in soil health means investing in public health. Smallholder farmers benefit from the health of the soil as crop yields increase and production systems become more efficient.

• Include investments in fertilizer and soil health in climate adaptation or mitigation

Climate change affects the relationship between fertilizer and soil health. Hence, investing in soil health improvements also contributes to increased farming system resilience.

• Implement policies that enable farmers to invest in soil health

Land tenure is key, but farmers continue to require fertilizer subsidies since alternative nutrient sources are lacking. Redesigning fertilizer subsidies is crucial to manage soil health.

Who can help improve soil health

• The global fertilizer industry needs to integrate soil health management in fertilizer recommendations and ensure that the right fertilizer formulations are available for the right crops and soils to maximize crop biomass production.
• Service providers need to integrate knowledge of soil health management practices into agronomic advisory services and share the information efficiently with farmers.
• Scientists need to identify and characterize key indicators for soil health and establish protocols and tools for rapid and efficient monitoring of soil health status.
• Policymakers need to encourage farmers to invest in soil health improvement, which is a longer-term objective requiring public support.
• Investors need to integrate soil health management as a key condition for financial support and implement health-promoting financial mechanisms.
• Civil society organizations need to raise awareness across society on the importance of soil health, the role of nutrient inputs, as well as its maintenance and improvement.
• The retail sector needs to include soil health-positive production practices in its processes for certifying responsible production.
• Consumers are encouraged to buy soil health-positive food and actively engage in discussions related to soil health.