Knowledge for Development

Soil science, indigenous knowledge and sustainable intensification: Implications for smallholder farming systems

Author: Oluwatoyin Dare Kolawole, Okvavango Research Institute, University of Botswana, Private Bag 285 Maun, Botswana

Date: 26/09/2013


By Walter M Simonson

In his article, Oluwatoyin Kolawole highlights key issues on the peculiarities of Africa’s soils and how they affect agricultural production. He argues that because of the very high diversity and spatial heterogeneity in soil type and quality across sub-Saharan Africa, a one-size-fits-all solution is inappropriate to address Africa’s divergent soil problems. Kolawole uses a number of research initiatives on integrated soil fertility management to show that Western science and local/indigenous knowledge are not mutually exclusive in driving sustainable management practices and improving yields on small farms. 


Soil science, indigenous knowledge and sustainable intensification: Implications for smallholder farming systems


Oluwatoyin Dare Kolawole, Okvavango Research Institute, University of Botswana, Private Bag 285 Maun, Botswana



Schiller (1980) observed that ‘…the earth has only 7.86 billion acres of land potentially suitable for agriculture, and we are already farming half that total’. Industrial growth and infrastructural development have likely reduced suitable land for agricultural production. The stiff contest for land for food production is becoming even more critical, as the world population, approximately 7 billion, is expected to grow to over 9 billion by 2050. Schiller (1980) suggested that the world ‘can boost agricultural production only by bringing the rest of the land into cultivation or by increasing the output per acre’. 

The desire of Norman Borlaug and his colleagues in 1966 to feed the world by pushing high-input-based agriculture originates in Malthus’ (1798 [1803]) theory of population, further buttressed by Schiller’s advice. Nonetheless, some have argued vehemently that high-tech-commercial agriculture or ‘big farms’ alone, may further jeopardize food security goals, rather than resolving the multifaceted problems associated with global food security (Robertson et al., 2000; Magnus and Caplan, 2002). While commercial agriculture plays a significant role in enhancing food availability and industrial growth, most gains may be obliterated by the negative side-effects on environment and human health if business remains as usual. 

Small farmers play a major role and have a cumulative effect on agricultural activities in the South, and are largely responsible for the food produced and consumed in developing economies. For instance, small farmers constitute 90% of food producers in Nigeria (Van Buren, 2001). Resource-poor farmers do not have the financial resources to acquire expansive land holdings. Frequently they rely on relatively small acreages to grow their crops and raise animals where applicable. How can a holistic and sustainable agriculture based on the ‘small farm’ model be developed?  

This article highlights key issues in the peculiarities of Africa’s soils and how they affect agricultural production. It suggests that Western science and local/indigenous knowledge are not mutually exclusive in driving sustainable agriculture in sub-Saharan Africa.  

Peculiar nature of Africa’s soils

The diversity in agro-ecological conditions in sub-Saharan Africa (SSA) is obvious. An aerial view of the landscape from the dry Sahel in North Africa down to the Kalahari Desert in Southern Africa shows a ‘rainbow effect’ in vegetation cover, mirrored by variations in soil types across the continent (Kolawole, 2013). Africa’s soils range from desert; poorly developed sand; Mediterranean; luvisols; luvisols and acrisols; nitrosols and acrisols; and ferrasols to lateritic soils (Scoones and Toulmin, 1999). Most tend to erode quickly, have low organic and nutrient levels, poor water-holding capacity and moisture stress (AGRA, 2009; CIAT/TSBF/ICRAF, 2002).  Low organic matter content is associated with low cation-exchange-capacity (CEC) and many of Africa’s tropical soils cannot release essential micro-nutrients for plant uptake, even following mineral fertilisation (Scoones and Toulmin, 1999). One major panacea for ensuring nutrient release is adequate organic fertilisation, which enhances soil structures (van der Pol, 1992).  

Soil properties not only vary across regions in Africa but across plots within a given farm (Vanlauwe and Giller, 2006). Field experience in northern Botswana highlights this (Box 1). A one-size-fits-all solution is inappropriate to address Africa’s divergent soil problems.  

Box 1:

In our study on integrated soil fertility management (ISFM) implementation in three rural communities (Makalamabedi, Nokaneng and Mohembo) in northwestern Botswana, 228 small farmers were selected in order to design a platform to enable the smallholders to engage with soil scientists in devising appropriate solutions to soil infertility problems. Laboratory analyses of nutrient status and CEC of 33 samples indicated that regardless of the small sizes of farmers’ plots, soil types varied within and between them. Most soils, especially in Makalamabedi and Mohembo, were very poor in nutrients such that most essential minerals and CEC were suboptimal for plant growth. Phosphorus is also a serious limiting factor in all sites. This emphasizes the appalling situation of soil health particularly in arid zone of the continent and the need to address the problem holistically. 

Credit: Ms Oarabile Mogobe (Research Scientist)

Current research in the major farming communities of the Okavango Delta, Botswana, comprises social surveys, soil analyses and stakeholder validation workshops. The social surveys focused on environmental, political economy and cultural issues, and farmers-scientists' perceptions on the implementation of soil fertility management projects. Results of laboratory analyses of soil samples were used to guide scientists on developing appropriate packages of recommendations on soil fertility management for small farmers. This contrasts with the arbitrariness of chemical fertiliser applications without prior soil tests. To ensure synergy and create a ‘transforming exchanges’ scenario, workshops were held for stakeholders (farmers, scientists and extension personnel) to validate the findings of previous social surveys and share views on how best to work together to implement sustainable soil fertility initiatives.  

Science, traditional practice and sustainable agricultural intensification

There are three viewpoints on enhancing soil fertility management in SSA: (1) that mineral fertilisers do not damage the soil and as such must be used persistently, although through certain guided procedures and in context-specific scenarios (Vanlauwe and Giller, 2006); (2) that the right combination of organic manure and mineral fertilisers is most important (e.g. AGRA, 2009); (3) that organic agriculture, with low use of external inputs (LEI), alone can achieve sustainable agriculture (e.g. OCA, 2013). The need for those engaged in formal (Western) science to recognise and incorporate farmers’ knowledge in agricultural development is fast becoming accepted – how much farmers’ knowledge is used and the impact of the synergy still remain unclear.  

A major impediment to rural development in Africa is the misconception of agricultural scientists and development agencies that small farmers are traditional and conservative ‘soil miners’ who wilfully take nutrients from the soil but are unable to replace them (Cleaver and Schreiber, 1994; World Bank-FAO, 1996; Buresh et al., 1997; Sanchez et al., 1997; Bationo et al., 1998; Eswaran et al., 2001; etc.). Naturally, such views prejudge the smallholders and muddle engagement with the farming clientele system, leading to patronising conclusions as to why and how farmers should take instructions from scientists and implement those recipes, accordingly.  

Regardless of its technological paraphernalia, one of the major problems associated with commercial agriculture is its mono-cultural practice, which resource-poor farmers avoid in their efforts to maximise the use of limited land at their disposal. Collectively, many smallholder farmers in SSA still have access to sizeable portions of arable land, although farm sizes are reducing in keeping with global trends. For instance, Nigeria has an estimated 71 million hectares of arable land, with half currently under cultivation mostly by smallholder farmers (IFAD, 2012).  

Smallholders continue to use traditional practices based on age-old farming systems models. In West Africa, for example, they practice both inter- and mixed-cropping, where a variety of crops are planted in rows and interlaced, respectively, on the same plot in a given farming season (Akinsanmi, 1990). Apart from providing diverse farm outputs at harvest, the methods maximise the use of land area, ensure weed control and prevent soil erosion as most soil surfaces are covered with crop plants (Akinsanmi, 1990; MacRobert, et al., 2007). The system also prevents soil water evaporation, while crop residues and shed leaves are a source of soil manure. Additionally, farmers also plant a variety of creeping and erect leguminous crops such as indigenous species of beans and pigeon pea (Cajanus cajan) interlaced with cereals and tubers. This enables nitrogen fixation, hence enhancing soil fertility. In south-western Nigeria, farmers intercrop cassava or yam with maize. Cassava takes little nutrient from the soil and replenishes it by shedding its leaves, which in turn serve as organic manure. Elsewhere, field experience shows that south-western Nigerian small farmers allow the natural growth of Siam weed (Euparotorum odoratum) on their fallowed plots to enhance soil fertility and structure in preparation for future cropping. Indian farmers intercrop pearl millet (a sole crop) with various legumes. This increases farmers’ income and enhances the availability of protein sources.  The  ILRI – ZimCLIFS project (Box 2),  shows how Zimbabwean smallholder ‘mixed’ crop-and-livestock farmers in four districts and two very different regions are being assisted to increase agricultural productivity and enhance food security through sustainable intensification (MacMillan, 2013).  

Box 2:

A 3-year joint project, Integrating crops and livestock for improved food security and livelihoods in Zimbabwe, (a.k.a. ZimCLIFS) was launched in 2012 by three CGIAR centres — the International Livestock Research Institute (ILRI), Africa; the International Maize and Wheat Improvement Center (CIMMYT), Mexico; and the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), India. The project seeks to ‘develop ways to increase agricultural production, improve household food security, alleviate poverty, and thereby reduce food-aid dependency in rural Zimbabwe through better integration of crop and livestock production and market participation.’ ‘The project has established field trials on 102 farm sites...’ In January 2013, a data collection training workshop was run by ILRI and CIMMYT staff. Conservation agriculture trials grew maize alongside livestock-palatable and -unpalatable legume species, for feeding livestock or biomass for soil cover, respectively. 


Scientific advances for improving soil fertility are crucial in increasing agricultural productivity. In many instances, soils are becoming exhausted and greater impact can be achieved, if scientists, without bias, partner with smallholder farmers who are custodians of context-specific knowledge to develop alternative methods that are environmentally-friendly. Such collaboration is needed to respond effectively to the challenge of feeding billions with dwindling land resources and degraded soils. Data on the extent to which farmers’ knowledge is incorporated in developing strategies for achieving sustainable intensification, and the impact of joint learning and experimentation which integrates both scientific and indigenous knowledge for improving soil fertility and agricultural productivity, are needed. 


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