Bernard Vanlauwe R4D Director, Central Africa Hub Nairobi, Kenya
IITA’s founding fathers, among others, were concerned with the low and declining land productivity in the face of growing populations and the inadequacy of traditional farming methods to curb this trend. Therefore, early research efforts were on land clearing, soil erosion, and zero tillage, combined with chemical weed control and small or medium level mechanization (Fig. 1). From the mid-1980s, attention began to shift towards existing production systems and their capacity for change and sustainable intensification (SI).
Alley cropping and planted leguminous fallows were on the agenda for several years, but were eventually replaced by technologies which were closer to the farmers’ own experience, such as dual-purpose legumes. These became part of the tool box of Integrated Soil Fertility Management (ISFM) (Fig. 2), which today is the pillar for soil and soil fertility management research. Its principles are aligned with those of SI, which encompass (i) increased production per unit of land, (ii) maintenance of essential soilbased ecosystem services, and (iii) resilience to shocks, especially climate change.
Search for the holy grail in soil and soil fertility management
From the late seventies, substantial efforts were made to develop and fine-tune “low input”, technologies such as alley cropping and herbaceous legume-based systems (including rotations, relay cropping systems, and live mulch systems). This was partly driven by the initial failure of Green Revolution approaches and the lack of favorable conditions for the use of agro-inputs on food crops.
The approach used in developing and promoting alley cropping systems followed the traditional technology transfer model where a lot of efforts went to fine-tune the systems before they were exposed to farming communities and promoted through development-oriented efforts (Fig. 1), as illustrated by the AFNETA (Alley Farming Network for Africa) project. Initial evaluations of herbaceous legume-based technologies established that the main interest of farming communities of a Mucuna fallow was the suppression of Imperata cylindrica rather than improved soil fertility. There was a massive effort in the second half of the 1990s to disseminate the Mucuna technology to farmers in Benin, by various investors and development organizations.
However, from the late 1990s, it was becoming clear that alley cropping and herbaceous legume-based technologies were not attracting the necessary farmer interest, mainly due to the lack of immediate returns on investment in land and/or labor. The focus moved to integration of grain legumes that led to the breeding of soybean for dual-purpose properties and promiscuity (Fig. 1). This was a commendable example of effective cooperation between a breeder and a soil microbiologist at IITA. The interest of farmers was immediate since such legumes not only provided immediate income through grain production but also the effects of the rotation on the subsequent maize crop were visible. Following its success, efforts were expanded to include cowpea and more recently groundnut and beans, supplemented with limited and targeted amounts of fertilizer, as research by the BNMS (Balanced Nutrient Management Systems) project.
The ISFM approach (Fig. 2), which is the cornerstone of today’s soil and soil fertility management R&D, is building on these earlier successes and complements the need for fertilizer with the necessary implements, including varieties, organic inputs, and other amendments, towards maximizing the use efficiency of these inputs. ISFM also recognizes that there is not one fit-for-all solution in relation to soil and soil fertility management, and that decision support tools are required to assist smallholder farmers in finding the right solutions for specific crops, production objectives, and overall environmental and institutional conditions.
Evidence of impact of investments in soil and soil fertility research
The early work of IITA did not warrant impact assessment since the technologies developed were not applicable to existing farming systems. Only with the shift to alley cropping and herbaceous legume-based interventions were efforts started to disseminate fine-tuned (most often under on-station conditions) solutions to farming communities.
For the Mucuna technology—the only herbaceous legume of the many evaluated that was promoted at scale—profitability for farmers was high as long as NGOs purchased the seed, artificially turning the species into a commercial crop. When this stopped in 1996, the adoption declined by 25%.
The decline in adoption of Mucuna and the abandonment or neglect of many alley cropping fields, revealed by impact studies, led to the virtual abandonment of these technologies by research and development organizations. Up to the mid-1990s, the impact of IITA’s soil and soil fertility management R&D on farming communities was low to nil although it must be recognized that many scientific outputs had been generated. Thus, in practical terms, impact-oriented NRM R&D at IITA started during the late 1990s.
No full-fledged impact study has been carried out to date in the savannas of Nigeria where the dual-purpose legumes were promoted, in combination with BNMS technologies although indirect evidence shows a large scope for meaningful impact (or important interest in uptake at pilot scale). Recent work in the CIALCA region indicated that while few farmers in the area have reached ‘full ISFM”, some components were taken up by substantial proportions of the target population with the uptake of specific technology components occurring sequentially rather than simultaneously.
A recent impact study in the CIALCA region showed that adoption of agricutural researchfor- development technologies reduced the probability of being poor by 13% and that a large share of this poverty reduction is causally attributable to adoption of improved crop varieties (32%) followed by adoption of postharvest technologies (28%) and crop and natural resource management (26%). These studies indicate that ISFM practices have scope for large-scale uptake although only formal adoption studies will provide the necessary evidence. Such studies are planned for some major investments in NRM (e.g., the N2Africa project).
The next 10 years
The concerns of IITA’s founding fathers remain as valid as ever, or even more so, with growing populations, ever-declining availability of good agricultural land, and new challenges such as climate change. Solutions for addressing soil and soil fertility management constraints commonly consist of several individual components that can interact with each other (as clearly demonstrated by ISFM, Fig. 2). Furthermore, such solutions require investments in agro-inputs and knowledge and skills, and are thus, per definition, limited to areas where the institutional environment is conducive for their uptake by smallholder farmers. Even then, not all farming households will be able or willing to invest in crop intensification practices, either by need (lack of resources) or willingly (no interest in intensifying agriculture).
Lastly, the full uptake of ISFM is a stepwise process whereby components are gradually added, often following logic (e.g., in the CIACLA region, fertilizer use was demonstrated to be higher in the presence of purchased maize seed). This makes the actual timing of impact studies quite important and supports the need for studies that look at changes over time, e.g., through panel studies. While not attempting to shy away from formal impact studies, the above observations demonstrate the many limitations such studies face when dealing with NRM-related topics.
Lastly and certainly not least, one major lesson learnt from the past 50 years is that a clearly impact-oriented and consistent approach to NRM R&D is required to ensure that the best practices get disseminated at scale. Changing the NRM R&D agenda too often, as was done regularly during the past 50 years, could have been another reason for delayed impact of these investments.