Associating yields with farming inputs
Four main inputs are identified in the small-scale farming system in the study area. These are inorganic fertilizers, animal droppings, compost, and improved seeds. The use of these inputs is neither uniform among all farmers nor constant from one agricultural season to the next. While all farmers participating in the study admit to having used all of these inputs at one time or another, not all farmers used the different inputs within the study period.
Use of inorganic fertilizers
The use of chemical fertilizers is associated with high mean yield increases (Figure 2). However, it must be noted that only 58% of the sampled farming population used any chemical fertilizers. Also, only about 66% of those using fertilizers were able to meet up to 50% of their fertilizer needs and about 39% satisfied more than 80% of their fertilizer needs. While some farmers may readily admit using inorganic fertilizers, the amount used is therefore rarely sufficient to achieve optimal results. Farmers also observe that the use of inorganic fertilizers is not necessarily constant over time. The ability to purchase and use fertilizers depends on the condition of the household prior to and during the farming season. Other needs may use up limited resources during the farming period and limit or prevent the household’s ability to afford fertilizers.
Use of animal droppings
Approximately 48% of sampled farmers used animal droppings, albeit insufficient in most cases (Figure 2). The use of animal droppings is shown to have the most substantial association with high yields (Figure 2). This ranking is based on comparison with the use of chemical fertilizers, improved seeds, and plant vegetal waste products. Animal wastes bring a cocktail of benefits to the poorly structured, low-nutrient soils of this region. Studies have documented such benefits [16, 17]. Besides providing more nutrients per unit volume relative to other organic fertilizer sources, animal droppings improve the soil structure through enhancing aeration and preventing compaction. The use of animal droppings therefore helps improve the soil’s moisture-retention capacity and provides room as well as favorable conditions for the growth of beneficial soil microbes [18]. Such improvements in structure, microbial composition and chemistry reduce erosion and also help to prevent nutrients from leaching. Animal wastes can be important in balancing extremes in high soil pH of the Western Highlands of Cameroon.
Use of improved seeds
Farmers who use improved seeds experience substantially better yields relative to those that do not use them (Figure 2). Farmers depend considerably on the quality of their seeds for viable crops and a good harvest. The traditional method of saving some of the previous harvest as seed for next year’s planting has gone on for several generations in Cameroon’s Highlands Region. Through such seed savings, smallholder farmers have been able to conserve many of the genetic material that has been used for several generations. Some of these genetic materials have survived different environmental challenges that the region has faced during this time. Research into seeds with higher production potential, pest resistance, drought tolerance and other beneficial traits for the region is bringing about improvements in some of the original seed stocks.
Use of vegetal waste (compost)
While the use of animal droppings may be seen as insufficient in such communities with limited access to chemical fertilizers, the use of plant residues in terms of compost is even lower. Farmers have the potential of generating appreciable amounts of vegetal waste products that can serve as inputs to farming activities through a variety of means. Vegetal matter with potential use as farm inputs can be derived from accumulated household kitchen debris and from farms after weeding and harvesting of crops. By converting these products into compost and using it on farms, farmers may reduce – and in some cases even provide all of – their fertilization needs [19]. Notwithstanding efforts by local authorities and local farming organizations at promoting the production and use of compost as a cheap and reliable source of farm fertilizer, only about 19% of sampled farmers use this technology at varying degrees of intensity (Figure 2).
Associating yields with dominant farming practices
In small-scale farming systems, the methods of plant residue management and the practice of intercropping are important in determining the availability of nutrients for plant growth. Residue management here refers to the incorporation of the plant material into the soil mix either in a decomposing or burnt form with the aim of fertilizing the soil. This is an important process in cases where small-scale farmers have limited economic potential to acquire synthetic fertilizers. Intercropping, on the other hand, is the practice of growing two or more crops in proximity [20]. Intercropping is practiced for a number of reasons: as an insurance against crop failure, to reduce the proliferation of plant pests, to enable non-nitrogen-fixing plants to benefit from leguminous mixes, and to sustain a harvest variety for home consumption [21, 22]. These two farm management techniques dominate much of the smallholder farming landscapes in Cameroon.
Forms of residue management and effects on yields
Burying of plant material below crop-bearing ridges
In this case, cleared vegetation is allowed to partially decompose at the surface of the farm. The decomposed vegetation is then gathered and laid in lines that eventually serve as ridges for seasonal crops. Soil from between these lines of decomposing vegetation is used to cover them, thereby forming the ridges. The vegetation continues to decay within these ridges for another 1 to 2 months before crops are planted on them. The lines of furrows from where the soil has been taken to form ridges for one season become ridges in the next planting season when crop residues are placed in them and soil from previous ridges is used to cover the residue. Farmers use basic tools (hoes) to form these ridges, making it a very laborious task and limiting the scale of use to small farms usually not larger than 1.5 hectares. The use of such techniques on larger farms requires cooperative labor from family, friends, or farming common initiative groups.
Localized surface burning of plant material
This is a localized process of burning plant residue on the farm with the goal of temporarily increasing fertility on a small patch and exploiting it for particular crops. Surface burning is more predominant where plant residue is plentiful and the process of burying all of it before burning is time and labor demanding. This is the case among small-scale farmers in the equatorial regions and its fringes, where above-ground biomass is usually plentiful. Burning is also the preferred choice for clearing the farm when farmers have limited time to prepare the farms for planting before impending rains.
Burying and burning of plant material (locally called ankara)
Ankara is the process of burning dry plant residue under a thin layer of soil. Ankara is a localized process practiced mainly among small-scale farmers and may involve either one ridge or a few ridges of a farm. Even small-scale farmers with land sizes <1 hectare rarely practice ankara on the whole farm, because this technique is such a localized, process mainly due to the limited availability of plant residue. Farmers see it as a process of concentrating plant nutrients on limited spots to optimize their use in high nutrient-demanding crops.
When averaged over fertilizers and cropping patterns, the burning of plant residue on the surface results in 20.5% greater yields than burying, while burning underground resulted in 80% greater yields than burying of plant residue (Table 1). The burning of plant residue underground resulted in significantly higher yields when compared with other methods of residue management at all fertilizer levels (Table 1). The exception to this is when 200–120–120 nitrogen:phosphorus:potassium fertilizer is applied in cases where residue was burnt on the surface. In this case, the increase in yields of 8% is not significant. The most significant difference among residue management techniques, however, is when residue is burnt underground with no fertilizer applied. The result is a sixfold increase in yields, which is 0.867 tons/hectare for burying residue, compared with 6.283 tons/hectare for burning residue underground (Table 1). Notwithstanding the relative profitability of practicing the burning of plant material underground as a residue management technique, it cannot be adopted on a whole-farm basis for many farmers. This is because farmers cannot obtain enough plant material to produce sufficient ash yield to make a difference for the entire farm, and hence specific spots are chosen to make use of the limited ash produced from burying the limited amount of plant residue.
Use of intercropping
Intercropping is a common feature of smallholder agriculture in Cameroon. Among the farmers studied, about 94% practice intercropping. While the crop combinations with which intercropping are practiced differ from one agro-ecological zone to the next, many characteristics of this practice are the same nationwide. Intercropping is carried out mainly on small farm sizes, generally those <2 hectares. Most intercrop mixes contain one leguminous crop. Crops within an intercrop are selected based on their importance for household consumption –the more market-oriented the farming, the less the variety of crops in the intercrop. While there are cases where food crops are intercropped with cash crops, the practice is predominantly carried out by food crop farmers.
The small size of farmland is one of the main motivations for the practice of intercropping. For a sample of 31 smallholder farmers, the mean size of the area cultivated is 0.9 hectares with a standard deviation of 0.39. Since most of the households depend heavily on farm production for most of their food, they tend to cultivate as much variety of food as the small farm portions can support. Intercropping is therefore an important aspect of livelihood diversification with the potential of diversifying the food basket of small-scale agricultural producers. Diversification of food and income sources is critical for economically deprived rural livelihoods in this region [23].
Yields and the control of diseases
Blight is an important plant disease for food crop producers in Cameroon. A soil-borne plant infection that is common in the Adamawa, west, northwest, and southwest regions of the country, blight can also be transmitted through infected seeds. Early blight occurs between November and February (the dry season) while late blight occurs between March and October (the dry season). Blight has been reported as the most important disease accounting for the most significant losses in common food crops of this region, such as garden huckleberries, potatoes, eggplant, and tomatoes [24–26]. Yield losses caused by late blight foliage infection can reach 71% in potato, 100% in tomato and 45% in garden huckleberry [27]. Potato tubers in storage can also be susceptible to blight when they are harvested from infected soils [24, 26]. Tests on 10 common potato varieties at Upper Farms, Bambili show a mean yield loss from the burden of disease of 23.3% with a median of 22.2% and standard deviation of 14% (Table 2). Access to knowledge and resources to contain blight infection can therefore greatly determine the gap between optimal yields and disease limited yields.
Yields and the sociocultural dimension of households
Gender perspectives of yields
The mean yield from male-managed farms is 1.8 tons/hectare of maize relative to just below 1 ton/hectare from female-managed farms (Figure 3a). The mean yield of 1 ton/hectare for female-managed farms has to be appreciated within the context of the overall data spread: about 60% of female farmers have yields that are at or below the 25th percentile (Figure 3a). These lower yields on female-managed farms are a reflection of the differences in factors of agricultural production (inputs and management) between genders. More than 85% of males used inorganic fertilizers in crop production, relative to about 54% of females (Figure 4). Also, males on average provided up to 60% of the optimum fertilizer needs for their farms while females provided approximately 30%. Such differences are also found in the use of other inputs and techniques that do have positive effects on crop yields, such as the use of compost, improved seeds, and animal droppings (Figure 3b).
Problems faced by women in Cameroon’s agriculture are very much akin to those faced by women in the rest of sub-Saharan Africa. Women share the burden of farm work in most households, yet they hold fewer agricultural assets such as farm tools and equipment of diverse farm-related activities than their male counterparts [28, 29]. The traditional gender division of labor can also serve to explain the differences in crop yields between males and females. In Cameroon there is a gender division of labor that ascribes the roles of childcare and household care to women [30, 31]. These roles are time consuming, thereby reducing the availability of women for activities that may improve their performance in agriculture such as the preparation of compost or collection or animal droppings. Another aspect of the gender division of labor in the agricultural sector is in the types of crops cultivated by male and female farmers [30]. In the North West region, men predominantly cultivate traditional cash crops such as coffee, bananas and a variety of fruits, while women cultivate staple food crops principally for household consumption. While men readily derive income from the sale of their produce, a portion of which they can reinvest on their farms, women can only sell if surpluses persist after household consumption.
Yields and level of education
An association exists between having some level of education and yields. While the difference between having a post-secondary school level education and an elementary-level education is minimal, the difference between A-level and no education is considerable (Figure 5). Also considerable is the difference between no education and elementary education (Figure 5). In the group of farmers studied, approximately 23% had received advanced formal education (post-secondary), 25% had elementary education and 52% had received no education. The data show some relationship between having some level of education and the use of inputs such as animal droppings, improved seeds and fertilizers. This may be because education enables farmers to access information on the potential benefits and drawbacks of available technologies. Farmers with some level of education tend to be more willing to test and adopt yield improvement technologies [32]. These farmers may therefore be in a position to distinguish more readily between what would provide better returns for their investments in labor or capital for different options at their disposal.
In Figure 5 the differences in yields between farmers that have undergone formal education and those who have not is less substantial than it is for other variables (such as the use of fertilizers, improved seeds, animal droppings). This inequality may be explained by other more subtle differences, such as the accumulated farming experience among older uneducated farmers. Older farmers can draw on their long years of farming experience in the region in managing a number of production constraints such as crop pests, nutrient conservation, incidences of dry spells and seed selection.
Education that can have a meaningful impact on agricultural productivity may not necessarily be formal. Opportunities for learning and skills development, such as FFSs, can make a difference. Farmers that have undergone some informal training in farming (through FFSs) will generally obtain significantly higher yields than those that have not (Table 3). Cases where farmers using traditional nonoptimized farming methods can yield more than those with trained skills, such as is the case in Lobo, are uncommon (Table 3). FFSs have proven to lead to significant positive outcomes with regards to food production per hectare, the adoption rate of new technologies and agricultural income [33].
Yields in relation to farm ownership and level of farm management
Yield differences are mirrored in the system of farm ownership and management (Table 4). Generally, low yields are associated with female-managed farms. Farms owned by female common initiative groups and male-managed farms produce intermediate to high levels of yields. Young farmers with specialized (not necessarily formal) training in food crop cultivation produce the highest yields (Table 4). The system of farm management can be divided into four levels: level 1, with limited inputs including poorly sourced planting material and dominantly traditional farming methods; level 2, with locally sourced soil improvement inputs (compost, manure) and planting materials with basic traditional farming methods; level 3, with moderate soil improvement inputs (fertilizers, compost, and manure) including planting material from specialized sources, improved farming methods, and limited or no control of diseases; and level 4, with optimal soil improvement inputs (fertilizers, compost, and manure) and planting materials from specialized sources, improved farming methods, and control of diseases.
The low yield from female-managed farms is also associated with low levels of management, while male-run farms receive high levels of management and are consequently associated with high yield outputs (Table 4). Worthy of note is the fact that, at the same levels of management, farms of female common initiative groups are associated with higher yields than individual female-managed farms. In this case, these differences can be explained by two main reasons. Firstly, collaboration towards a common cause by female common initiative groups entails mobilizing greater inputs of labor to tackle farming chores in a timely and efficient manner. This collaboration also means that the deficiencies of individuals within the group can be supplemented by the strengths of other members during the farming process. Increasingly, national agricultural development institutions have tended to appreciate the role of common initiative groups and cooperatives in fostering food production at grassroots level.
Choice of crops to cultivate and implications on yields
The process of decision-making in households on types of food crops to plant is very complex. Mapping out the complete system interaction of variables associated with decision-making on the choice of crops that farmers decide to grow at each time may be very challenging. However, it is possible to identify the main factors that are considered before these decisions are made (Figure 6). An understanding of these factors is important in revealing the motivation for cultivation of different crops. Given the heavy dependence of small-scale farmers on natural factors for agricultural production, one may expect to find that where agro-ecological suitability for the cultivation of a particular crop drives its production, the gap between maximum attainable yields and farmers’ yields is likely to be smaller. On the other hand, where cultural demands predominate over agro-ecological suitability in farmers’ decisions about which crops to cultivate, the gap between maximum attainable yields and farmers’ yields is likely to be larger. Figure 6 shows a strong influence of cultural demands on the choice of crops that are cultivated. The cultivation of crops because they constitute the staple food ranks highest in farmers’ consideration when they make decisions on which crops to cultivate (Figure 6). The basis for estimating the yield gap based on agro-ecology and culture as major drivers of the choice of crops cultivated is dependent on the assumption that there is little or no yield-enhancing input in agriculture. This assumption is true for a majority of smallholder farmers in Cameroon, as it is for most regions of West Africa and Central Africa [34].
Other important factors determine farmers’ choice of crops and are neither directly cultural nor agro-ecological. These factors tend to be more economic and social in nature. They include the availability of seeds, the size of agricultural land, payment for hired labor, the availability of family labor, destruction by livestock, crop theft and the cultivation of crops primarily for sale (Figure 6). Important to note is that, at the very grassroots of rural smallholder production, the farming of food that is staple for household consumption remains the main driver of choice for crops to cultivate (Figure 6). Being a household staple food is the most important consideration, ranked highest at seventh on a 7-point scale relative to agro-ecological considerations such as closeness to water source and problems of rainfall, ranked second and third on a 7-point scale (Figure 6). Other agro-ecological considerations such as problems of pests and soil suitability do not feature in farmers’ lists of considerations.