Dr Shamie Zingore, Director of Research and Development at the African Plant Nutrition Institute, delves into the relationship between soil health, crop productivity and human nutrition.
Africa is home to an estimated 33 million smallholder farmers who contribute about 70 per cent of the continent’s food supply. But these farmers face various constraints, such as low productivity and limited access to new agricultural technologies. The soils in sub-Saharan Africa (SSA) in particular are some of the poorest in the world due to naturally low fertility and insufficient soil conservation measures. It is estimated that the continent loses over US $4 billion worth of soil nutrients each year, severely eroding its ability to feed itself. Crops require an adequate and balanced supply of nutrients to produce good yields, yet currently, more than 60 per cent of SSA’s agricultural land faces challenges around crop production.
Current crop nutrient management practices – managing the chemical elements and compounds essential for plant growth and production – on smallholder farms are inadequate. Increasing the yields of food crops will depend, to a large extent, on innovative crop and soil management practices that effectively address low soil fertility and build the resilience of food systems in the region.
Sustainable and effective management of nutrients is taking centre stage at this year’s AGRF Summit, and is an opportunity for stakeholders to discuss interventions and priority actions for delivering technologies for agricultural development. This is more important than ever at a time of global volatility due to the food and fertilizer supply chain disruptions triggered by the COVID-19 pandemic and the Russia-Ukraine conflict.
A new approach to nutrient management
To effectively address food security challenges in SSA, soil and nutrient management technologies must balance increasing crop productivity while building soil fertility. In the long-term, they should foster resilience and increase the nutritional value of the food produced.
The 4R Solution, for example, is a project launched by the Co-operative Development Foundation of Canada and Fertilizer Canada. Working in partnership with other local organisations, 4R Solution initiated the 4R Nutrient Stewardship, which helps smallholder farmers in SSA improve agricultural practices, in particular sustainable nutrient management.
Adopted by the African Plant Nutrition Institute, 4R Nutrient Stewardship takes into account the economic, social, and environmental dimensions of nutrient management, such as farm profits, and food and water security, all of which can affect crop production. It provides a framework for smallholder farmers to achieve cropping system goals, including increased production, farm profitability, enhanced environmental protection and improved sustainability.
To achieve these goals, the 4R Nutrient Stewardship concept includes four critical considerations for farmers:
- RIGHT SOURCE – Ensure a balanced supply of essential plant nutrients, considering both naturally available sources and the characteristics of specific products, in plant-available forms.
- RIGHT RATE – Assess and decide the correct amount of nutrients to apply based on soil nutrient supply and plant demand.
- RIGHT TIME – Assess and make decisions on the timing of nutrient application based on the dynamics of crop uptake, soil supply, nutrient loss risks, and field operation logistics.
- RIGHT PLACE – Address root-soil dynamics and nutrient movement, and manage spatial variability within the field to meet site-specific crop needs and limit potential losses from the field.
The framework was initially adopted in Kenya in 2019 and has since been scaled up. Today, it supports more than 50,000 smallholder farmers in Ethiopia, Ghana and Senegal through field-based training and educational programmes on extension systems. This helps local farmers to adopt crops and technologies appropriate to their challenges and needs. A pilot study in Western Kenya found that the yield of major food crops – including maize, sorghum, millet, beans and soybean – were 100-300 per cent higher on farms that used the 4R Framework practices.
Farmer-friendly support tools
A challenge prevalent in many SSA countries is that of ‘hidden hunger’ — the lack of specific micronutrients in the food produced and consumed by farmers. However, an adequate supply of micronutrients in fertilisers can reduce malnutrition because it increases the micronutrient content of the food produced and consumed by smallholder rural households. The 4R framework is instrumental in providing guidelines on this.
Another tool is Nutrient Expert, which is a simple, computer or mobile phone-based support platform that helps farmers make informed decisions on using the right amount of fertilisers and organic resources. By integrating information on climate, soil fertility conditions, and the target yield, Nutrient Expert provides farmers with advice on how to best balance nitrogen, phosphorus, potassium, in addition to secondary- and micronutrients in soil. This prevents over- or under-supplying nutrients, which can lead to environmental problems or yield losses. In Western Kenya, for example, Nutrient Expert introduced maize growers to fertilizers with potassium, which were not traditionally used. As a result, yields increased by 20 per cent.
Bringing innovation to farmers
Strengthening collaborative research between public and private sector agricultural development and extension programmes can guide large-scale and long-term investments in technologies. Furthermore, they can also support the development and dissemination of 4R framework practices to farmers and other stakeholders. On-farm demonstrations of best practices adapted to site-specific soil, climate, and crops serve as learning sites for farmers and extension service providers.
Improving crop nutrient management for smallholder farmers in SSA can reduce malnutrition and address food security. Through innovative initiatives such as Nutrient Expert and 4R Nutrient Stewardship, farmers can make more informed decisions around nutrient levels in their crops. The AGRF Summit – of which this year’s theme is Grow. Nourish. Reward – Bold Actions for Resilient Food Systems – is more important than ever to drive solutions for the food and agriculture agenda in the continent.
Table 1. Yield improvement for major food crops with 4R practices on smallholder farms in Western Kenya.
| Crop | Average farm yield | 4R site yield |
| Maize | 2.2 | 6.0 |
| Sorghum | 0.6 | 2.5 |
| Millet | 0.4 | 1.5 |
| Beans | 0.8 | 2.0 |
| Soybeans | 0.7 | 2.0 |