In recent years, many studies have demonstrated the heterogeneity of the smallholder production environment. Yet agronomic research for development (R4D) that aims to identify and test options for increasing productivity has not consistently adapted its approaches to such heterogeneous conditions. This paper describes the challenges facing research, highlighting the importance of variation in evaluating the performance of soil management recommendations, integrating aspects of production risk management within the formulation of recommendations, and proposing alternative approaches to implement agronomic R4D. Approaches are illustrated using two multi-locational on-farm paired trials, each having one no-input control treatment and a treatment with fertilizer application for maize in Western Kenya and for beans in Eastern Rwanda. The diversity of treatment responses should be embraced rather than avoided to gain a better understanding of current context and its relation with past management.

Nitrogen (N) losses greater than 40% in furrow-irrigated cropping systems are a common problem that substantially limits yields. Sustainable production methods are therefore required to reduce these losses and increase the yield under semi-arid conditions. A field trial was carried out to study the soil N dynamics and soil physicochemical properties in soils amended with organic manure (i.e. with poultry manure (PM), farmyard manure (FYM) and pressmud compost (PrM)). Soil N dynamics and properties were evaluated under different ridge to furrow ratios (1:1 and 2:1) as well as maize yield and profitability. When ridge to furrow ratio increased (2:1) in soils amended with PM, the inorganic and organic N status was increased and N losses were reduced. This strategy lowered soil pH, and maximized organic matter status and maize yield. The highest yield, net income and benefit–cost ratio were attained with 2:1 ridge to furrow ratio and PM amendment, being an alternative management for increasing maize productivity and profitability while improving nutrient use efficiency.

More than 10 Sub1 rice varieties carrying the submergence-tolerance gene have been released for flood-prone environments in tropical Asia. Improved management practices have been shown to enhance yields of these varieties. The objective of this study was to dissect the growth response of IR64-Sub1 to integrated crop management in a flash flood at the late vegetative stage. Field experiments were conducted at the International Rice Research Institute, Philippines in the dry and wet seasons of 2013. Complete submergence was imposed for 14 days starting at 37 days after transplanting. Integrated management practice (IMP) consisting of: (i) application of fertilizer (compared with no fertilizer use in conventional practice), (ii) use of lower seeding rate (400 vs. 800 kg ha−1) in the nursery bed, (iii) use of slightly older seedling for transplanting (30 vs. 18 day-old), and (iv) higher planting density (33.3 vs. 25.0 hills m−2) gave yields higher by 8–87% compared with the conventional practice (1.3–2.4 t ha−1) in both seasons. This was attributable to higher shoot biomass after water recession, more tillers m−2, greater leaf area expansion and shoot biomass accumulation during the recovery period, and higher filled-grain percentage at maturity. The improved management had no positive effect on panicle formation, spikelets panicle−1, and harvest index since stress was imposed at the transition period between vegetative and reproductive phases. Our results suggest the appropriate nursery management, for submergence-resilient seedlings to further alleviate damage caused by flash floods and increase the yield of Sub1 varieties in flood-prone rainfed lowlands.

The low yield of pearl millet largely due to the low adoption of improved varieties substantiates the application of client-oriented plant breeding for pearl millet. Hence to enhance adoption, new varieties must correspond to farmers’ preferences and respond to the constraints prevailing in the production environments, participatory rural appraisals were conducted in two agro-ecological zones (Sahel and North-Sudan) to determine farmers’ preferences in the choice of varieties and to identify constraints to pearl millet production. The study revealed that the major production constraints are hierarchically drought, Striga, head miner, bird and downy mildew. Compact panicle, large grain size and non-bristle panicle were the most preferred traits in pearl millet across agro-ecological zones. Very long panicle and early maturity crop cycle were more preferred in the Sahel zone whereas, in the North-Sudan zone medium panicle length and medium maturity cycle were more preferred by farmers. Traits largely rejected by farmers were small grain size, narrow, loose and bristled panicle. Very few investigations were done to understand the raison of the low adoption of improved technologies in pearl millet. This study identified the major criteria of new pearl millet variety adoption by farmers. It is expected that breeding program must integrate these criteria in new pearl millet variety profiling to enhance adoption.

Given the importance of irrigation for rice production, this study compared the technical efficiency of irrigated and rain-fed rice (Oryza sativa) farms in the Upper Niger River Basin and Rural Development Authority (UNRBDA), Nigeria. Primary data were collected from 300 irrigators and 325 rain-fed rice producers. Applying the stochastic frontier Cobb–Douglas production function, net income analysis and Likert scale rating techniques, the study found that irrigated scheme increased marginal factor productivity and profitability. The study revealed the existence of large technical inefficiency in rain-fed farms when compared with irrigated farms. This suggests that there is room for output gains through technical efficiency improvement in the rain-fed system. The mean value of the marginal physical product of inputs (VMPPX) in the irrigated farms (₦2.32) was more than that of rain-fed farm (₦1.67). Thus, if the average producers in the rain-fed are to achieve the technical efficiency level of the average producer in the irrigated farms, they can realize 38% output gains. Similarly, the mean net farm income (NFI) of ₦62,280.00 per ha in the irrigated farm was more than double of that of rain-fed farms ₦22,391.00. The partial regression coefficients for the individual production factors (β1) and (β3) for labour input (X1) and other variable inputs (X3), respectively, were positive and significant at 1% level, suggesting that the partial elasticity of crop output with respect to labour and other costs was higher in the irrigated farms than in the rain-fed farms. The Likert scale rating techniques showed that the poor knowledge of irrigation techniques, insufficient water for irrigation during the dry season, high cost of labour and lack of access to credit were the critical constraints preventing the rain-fed rice producer from joining the irrigation scheme. In view of this, rice irrigators should be encouraged to train more rain-fed farmers on some rudiments of irrigation techniques. They should also be linked to the sources of finance. Water Users Association (WUA) should be established in communities within the scheme areas for effective communication between farmers and the officials of the UNRBDA. Decision on the allocation of resources to Fadama sites including water should be given to WUA to strengthen the membership of the organization, while the government officials serve as supervisory and advisory body.

Root-knot nematodes represent a serious threat to world coffee production, especially Meloidogyne incognita and M. paranaensis. Most cultivars of Coffea arabica are highly susceptible to these parasites and cultivation in infested areas has only been possible with the use of resistant C. canephora rootstocks. In this research, three elite clones of C. canephora, selected in areas infested by M. incognita and M. paranaensis, were evaluated in controlled conditions to assess levels of resistance against two populations of M. paranaensis, four populations of M. incognita and a mixed population of both species. The three clones were resistant to both species, but CcK1 and CcR2 were considered most promising because their vegetative growth was not impaired by nematodes.

Perennial grain crops have been proposed as a transformative approach to agriculture. Replacing annual staple crops with perennialized growth types of the same crops could provide environmental services, improve labour efficiency and weather resilience, reduce seed costs and produce livestock fodder or fuelwood production. Yet, the technologies and science for agricultural development in Africa have focused almost exclusively on annuals. In this paper, we review the literature to explore what has been potentially overlooked, including missed opportunities as well as the disadvantages associated with perennial grains. The case studies of pigeon pea and sorghum are considered, as an analogue for perennial grain crops in Africa. We find that a substantial number of farmers persist in ‘perennializing’ pigeon pea systems through ratoon management, and that sorghum ratoons are widely practiced in some regions. In contrast, many crop scientists are not interested in perennial traits or ratoon management, citing the potential of perennials to harbour disease, and modest yield potential. Indeed, an overriding prioritization of high grain yield response to fertilizer, and not including accessory products such as fodder or soil fertility, has led to multipurpose, perennial life forms being overlooked. Agronomists are encouraged to consider a wide range of indicators of performance for a sustainable approach to agriculture, one that includes management for diversity in crop growth habits.

Agriculture research often focuses on a technical problem. However, the most effective researchers usually intuit that this entry point is not sufficient to make themselves useful to farmers and nudge systems. Yet non-technical work frequently goes undocumented leaving many of the drivers of success unstudied. This paper attempts to understand the factors that contributed to the wide utilization of native crop varieties and species that were being promoted by the Ecuadorian National Agriculture Research Institution. The results show that what really made a difference in farmers' lives and the overall food system was increasing farmers' knowledge and capacity to produce quality seeds, promoting the consumption of these crops to national consumers, and linking farmers to outside groups. As a result, over a period of five years three case studies on three different farmer groups showed adoption rates of new varieties of between 20–50% and that they were able to produce approximately 7.5% of the annual demand for quinoa and lupin seed in Ecuador, from a starting point of virtually nothing. The research shows that the added value of a research institution might not be known at the beginning of the intervention, but rather will emerge over time through dialogue and negotiation based on systematic understanding of the context. Therefore, an appropriate stance for external organizations is to begin with an awareness of the existing assets of a specific farmer group and provide options that can be leveraged by local communities.

Establishment of young cacao trees in West Africa can be severely impeded by the onset of the dry season. To address this issue, a field experiment was conducted in Ghana to examine whether different mulch treatments and irrigation applied during the dry season combined with overhead shade could improve survival, early growth and yield of cacao. The mulch treatments used were polyethylene film and coffee husks placed around the young plants. Irrigation was used as a positive control, and no mulching or irrigation was a negative control. Three shade regimes were provided through different arrangements of Gliricidia sepium and plantains. Four different cacao clones were used in the study in a replicated split-plot design. Early growth of cacao was stimulated under the irrigation and plastic mulch treatments. Higher rates of photosynthesis during the dry season appeared to underlie these increases. Significantly higher early yields were also observed under the irrigation and coffee mulch treatments compared with the control. Plant survival varied significantly between treatments; irrigation was associated with the highest plant survival (94%), followed by the plastic mulch treatment (91%), coffee husk (82%) and the control (70%). There was also an increase in survival when more intense shading was used. Under zero mulch conditions, differences in survival were observed between clones. The clones P 30 [POS] and SCA 6 were more sensitive to drought (in terms of survival) than PA 150 and T 79/501. It is concluded that relatively simple mulching techniques or controlled irrigation in conjunction with appropriate shade management can significantly improve early establishment and cropping of cacao.

Agroforestry systems (AFS) can serve to decrease ecosystem carbon (C) losses caused by deforestation and inadequate soil management. Because of their shade tolerance, cacao plants are suitable to be grown in AFS, since they can be combined with other kinds of trees and shrubs. The potential for C sequestration in cacao farming systems depends on various factors, such as management practices, stand structure and plantation age. We compared conventionally and organically managed cacao monoculture systems (MCS) and AFS in Sara Ana (Bolivia) with respect to C stocks in plant biomass and to amounts of litterfall and pruning residues. The total aboveground C stocks of the AFS (26 Mg C ha−1) considerably exceeded those of the MCS (~7 Mg C ha−1), although the biomass of cacao trees was greater in the MCS compared to the AFS. Due to higher tree density, annual litterfall in the AFS (2.2 Mg C ha−1 year−1) substantially exceeded that in the MCS (1.2 Mg C ha−1 year−1). The amounts of C in pruning residues (2.6 Mg C ha−1 year−1 in MCS to 4.3 Mg C ha−1 year−1 in AFS) was more than twice those in the litterfall. Annual nitrogen (N) inputs to the soil through pruning residues of cacao and N-fixing trees were up to 10 times higher than the N inputs through external fertiliser application. We conclude that appropriate management of cacao AFS, involving the pruning of leguminous trees, will lead to increases in biomass, litter quantity and quality as well as soil C and N stocks. Thus, we recommend stimulating the expansion of well-managed AFS to improve soil fertility and enhance C sequestration in soils.

Pea is a self-pollinated, diploid (2n = 14), annual crop produced worldwide for human consumption and animal feed. The exploitation of maximum genetic potential from available pea resources implies the knowledge of genetic parameters of yield components. Hence, the present study was conducted in a cross between two pea varieties, namely DDR14 and Explorer, its F2 progeny and F3 families to find out transgressive segregants and to determine the magnitude of narrow sense heritability and heterosis. The high narrow sense heritability values obtained indicated that rapid gain could be achieved through selection for the different traits; however, the presence of genotype x environment interaction could limit the correspondence of these estimated values with the observed ones. The selection of lines through their phenotypic values is influenced by environmental and error effects. Best linear unbiased prediction (BLUP) was used for the prediction of genotypic values using morphological data from different years, allowing the correction for environmental effects. These estimates were used for genetic analysis of the traits. Heterosis was observed for number of pods (27.1%) and number of seeds (23.3%), characters that have a direct effect on yield. The cross also showed high frequency of transgressive segregation for these characters in F3 generation (15.5% and 13.6%, respectively). There were 12.73% families transgressive for two or more characters, with genotypic values of 49.82–64.41 for number of pods and 153.75–189.59 for seed number. The crossing between Explorer and DDR14 provided a base for the selection of superior progeny.

Competition from weeds is one of the major biophysical constraints to rice (Oryza spp.) production in sub-Saharan Africa. Smallholder rice farmers require efficient, affordable and labour-saving weed management technologies. Mechanical weeders have shown to fit this profile. Several mechanical weeder types exist but little is known about locally specific differences in performance and farmer preference between these types. Three to six different weeder types were evaluated at 10 different sites across seven countries – i.e., Benin, Burkina Faso, Côte d'Ivoire, Ghana, Nigeria, Rwanda and Togo. A total of 310 farmers (173 male, 137 female) tested the weeders, scored them for their preference, and compared them with their own weed management practices. In a follow-up study, 186 farmers from Benin and Nigeria received the ring hoe, which was the most preferred in these two countries, to use it during the entire crop growing season. Farmers were surveyed on their experiences. The probability of the ring hoe having the highest score among the tested weeders was 71%. The probability of farmers’ preference of the ring hoe over their usual practices – i.e., herbicide, traditional hoe and hand weeding – was 52, 95 and 91%, respectively. The preference of this weeder was not related to gender, years of experience with rice cultivation, rice field size, weed infestation level, water status or soil texture. In the follow-up study, 80% of farmers who used the ring hoe indicated that weeding time was reduced by at least 31%. Of the farmers testing the ring hoe in the follow-up study, 35% used it also for other crops such as vegetables, maize, sorghum, cassava and millet. These results suggest that the ring hoe offers a gender-neutral solution for reducing labour for weeding in rice as well as other crops and that it is compatible with a wide range of environments. The implications of our findings and challenges for out-scaling of mechanical weeders are discussed.

The agricultural research and development institutions in most developing countries are poorly equipped to support the needs of millions of smallholder farmers that depend upon them. The research approaches taken by these systems explicitly or implicitly seek simple, one-size-fits-all solutions for problems and opportunities that are extremely diverse. Radical change is needed to facilitate the agroecological intensification of smallholder farming. We propose that large-scale participatory approaches, combined with innovations in information and communications technology (ICT), could enable the effective matching of diverse options to the wide spectrum of socio-ecological context that characterize smallholder agriculture. We consider the requirements, precedents and issues that might be involved in the development of farmer research networks (FRNs). Substantial institutional innovation will be needed to support FRNs, with shifts in roles and relationships amongst researchers, extension providers and farmers. Where farmers’ organizations have social capital and strong facilitation skills, such alignments may be most feasible. Novel information management capabilities will be required to introduce options and principles, enable characterization of contexts, manage data related to option-by-context interactions and enable farmers to visualize their findings in useful and intelligible ways. FRNs could lead to vastly greater capacity for technical innovation, which could in turn enable greater productivity and resilience, and enhance the quality of rural life.

Sustainable intensification (SI) of agriculture is the predominant objective for agricultural research and extension worldwide. Researchers and policymakers consider SI to be essential to avoid global hunger, improve human nutrition and reduce rural poverty while avoiding all manner of environmental disasters. To achieve these global public goods requires a large number of rural households – ‘small farmers’ – in less developed countries to improve their agriculture. Household size and farm size from 11,789 households in 15 countries from sub-Saharan Africa were used to calculate an intensification benefit index (IBI) that reflects how much a household will benefit if intensification occurs. IBI is defined as the increase in personal daily income (cents/person/day) as returns to land (dollars/hectare/year) increase. Actual net farm income from 160 rural households in each of three countries was compared with their IBI values to explore the gap between potential intensification and current smallholder farm performance. Fifty percent of all households had IBI values less than 0.075 cents/dollar, 70% less than 0.125 cents/dollar and 90% less than 0.225 cents/dollar. Returns of $1000/ha/year would result in fewer than 15% of households crossing a $2/person/day poverty line; $2500/ha/year would be required to lift 50% of the sample above the line; and even with $4000/ha/year, more than 30% of households would remain below the line. Since mean net returns from three sub-sampled sites were only $78, $83 and $424/ha/year the gap between potential- and actual performance is large but, theoretically, amenable to closure through adoption of improved technologies. However, surveys have shown that the available technologies would struggle to bridge the gap completely for rural households with small farms. For many small farms, the gains from adopting improved technologies are unlikely by themselves to lift them out of poverty and so might not be as attractive as scientists would wish.

Smallholder livestock systems in Central America are typically based on pastures with traditional grasses and associated management practices, such as pasture burning and extensive grazing. With the rise of the global population and a corresponding increase in demand for meat and milk production, research efforts have focused on the development of improved grasses and the incorporation of legume species that can increase productivity and sustainability of Central American livestock systems. However, farmer adoption remains very limited, in part due to the lack of site-specific evaluation and recommendations by local institutions. Using a multi-site participatory approach, this study examined the potential of five improved grasses and five species of forage legumes as alternatives to the broadly disseminated grass Hyparrhenia rufa (cv. Jaragua) in pasture-based cattle systems in western Honduras and northern El Salvador. Improved grasses (four Brachiaria sp. and Megathyrsus maximus) produced significantly more biomass than H. rufa; also four of the five legume varieties evaluated (Canavalia ensiformis, Canavalia brasiliensis, Vigna unguiculata, and Vigna radiata) demonstrated high adaptability to diverse environmental conditions across sites. Farmer participatory evaluation offers a valuable means to assess performance of forages and will likely contribute to their improved utilization. Future research is needed on more refined management recommendations, pasture system design, costs and environmental benefits associated with the adoption of these forages in local livestock production systems.

The expansion of sugarcane crop to regions with lower water supply in Brazil has increased the importance of correct estimation of crop water requirements. Currently, the irrigation management is generally done using the crop coefficient (Kc) based on the FAO 56 bulletin. Kc is used to determine the potential water demand of the crop for a given period of time and is considered constant for each crop stage. However, some recent studies have shown that Kc can be significantly variable under different evapotranspiration (ETo) rates. This paper aimed to analyse sugarcane water consumption at different scales: plant (sap flow measurements by energy balance method); canopy (Bowen ratio energy balance method); and plant–atmosphere coupling (infrared gas analyser) to reduce the uncertainties on the irrigation practices. Measurements were taken at two experimental sites, where a modern Brazilian cultivar CTC 12 was grown under drip irrigation and an old main Brazilian cultivar (RB867515) was grown under sprinkler irrigation by a central pivot. The mean crop evapotranspiration (ETc) values by the Bowen ratio energy balance method were 2.92 and 3.68 mm d−1 for RB867515 and CTC 12, respectively, resulting in a mean Kc of 0.99 at the full vegetative growth stage. Kc values were dependent on ETo and varied between 0.2 and 1.7 for both cultivars. This occurred in a crop coupled to the atmosphere (Ω = 0.37) and was the same found in other coupled crops such as coffee and citrus. In conclusion, the sugarcane Kc for southeast Brazil presented temporal variability due to coupling conditions according to reference evapotranspiration, and this should be considered in irrigation management.

An experiment was carried out to assess the benefits of native arbuscular mycorrhizal fungi (AMF) for banana plants cv. ‘Nendran’. The AMF species applied were Funneliformis mosseae and Glomus microcarpum, which were identified in a previous survey as the most common root associates of Musa spp. in traditional monoculture banana fields. Spores of both the AMF species isolated from the natural banana fields were mono-cultured and used in the experiment, individually and in combination, at two inoculum spore levels (2500 or 5000 spores). We evaluated the root colonising potential of AMFs and their effects on plant height, chlorophyll content and leaf N, P and K concentrations at regular intervals up to 90 days after inoculation. All the inoculated plants showed more than 80% root colonisation. Increase in chlorophyll content in the leaves was found significant in all treatments, with the exception of the combination of 5000 spores of F. mosseae and 5000 spores of G. microcarpum each. Increases in leaf N, P and K were found in all the inoculated plants as compared to control (sterile soil without any AMF). While a significant reduction in soil available nitrogen and soil pH was observed in all treatments with inoculation, the soil available phosphorus and soil total organic carbon were increased by inoculation. Overall data revealed positive effects of AMF species in banana, especially during its early growth. As AMF species were isolated from fields differing in relation to banana variety and soil type and have positive effects in banana nutrition, an integrated soil fertility management using AMF appears promising.

This research sought to link Andean soil knowledge and farmer categorization of soil fertility to soil science characterization of soils, and use these to understand the impacts of phosphorus (P) fertilization of legumes using rock phosphate and soluble P fertilizer in 17 smallholder-managed sites with varying soil properties. We found that farmer high/low categorization of soils corresponded to soil P fertility and distance from farmer dwellings. Measures of soil P fertility also were inversely related to mycorrhizal colonization of vetch roots and directly related to the potential for P release by legume residues (C:P ratio). However, particular soil properties (texture and calcium phosphate pools) were better in explaining the response of legume biological nitrogen fixation to P addition, with maximal impacts in low-clay soils and soils with low calcium phosphates, as assessed with a dilute HCl extraction. In these conducive contexts, legume BNF increased 67 and 150% for RP and TSP, respectively (p < 0.05), with similar increases in biomass P stocks that showed promise for soil regeneration. In low-P fields, added P increased potential P release from legume residues via lower C:P ratios (p < 0.05). Percent cover of soil increased from 35% in the control to 45 and 55% with RP and TSP (p < 0.05), which shows potential for reduced erosion risk under P fertilization of legumes. We discuss results with respect to the integration of local farmer knowledge systems with exogenous scientific knowledge.

Green manures (GM) as an alternative to inorganic fertilizer offer considerable potential as a source of plant nutrients and organic matter (OM). Hence, field experiments were carried out during 2015 and 2016 cropping seasons to compare impacts of GM and NPK (15:15:15) fertilizer on soil properties, growth, fruit yield, mineral, lycopene and vitamin C contents of tomato (Lycopersicon esculentum Mill). GMs were composed by green tender stems and leaves of pawpaw (Carica papaya L.), neem (Azadirachta indica A. Juss.), moringa (Moringa oleifera Lam.) or gliricidia (Gliricidia sepium (Jacq.) Kunth ex Walp.) and applied at 5 Mg ha−1, whereas NPK was applied at 300 kg ha−1 and there was a no fertilizer plot (control). Application of GMs reduced soil bulk density and increased soil OM, N, P, K, Ca, Mg, growth, number of fruits and fruit yield of tomato compared with the control. NPK fertilizer had no effect on soil bulk density and soil OM, but it increased soil fertility and tomato yield as compared with the control. When comparing treatments, the highest tomato yield and best cost:benefit ratio were obtained with gliricidia as GM. The GMs and NPK fertilizer increased mineral, lycopene and vitamin C contents in tomato fruits and the highest K, Ca, Fe, Zn, Cu, lycopene and vitamin C contents in tomato fruits were found with moringa as GM. Our results revealed that GM has potential to improve soil properties, tomato yield and quality, being an alternative for cropping management.

Consider a field experiment laid out in a randomized complete block design in which you study three types of fertilizers for two winter wheat cultivars. One year, one location – the experiment is not repeated. You design it and then spend a lot of time and money to conduct it. You cultivate the soil and take care of the plants; you worry about them; you never know what can happen, so you cannot wait for the crop to be harvested. And that day finally comes. The crop is harvested, and everything is fine. And here you are, all went great, you have the data in hands, and now a simple thing to do – analyse them. Well, yes, the experiment was conducted in one year, and you are aware you cannot be sure the outcome would be the same next year or elsewhere, but whatever – suffice it to consider the conclusions as preliminary and get on with the interpretation. Why should you not? It was a properly designed experiment that took samples from the underlying infinite populations of the two winter wheat cultivars in the three water regimes studied. Statistics is here to help you out, is not it? Well, it is not. Statistics will not help you out whether the experiment was poorly designed. Agricultural science literature seldom explains what populations are studied and what types of samples are taken in designed experiments. To fill this gap, we discuss various aspects of the sampling process in designed experiments. In doing so, we look at the survey sampling methodology, a statistical framework for studying finite populations – we do this because survey sampling has developed into the advanced theory of sampling processes, and this background can help us understand the intrinsic aspects of sampling in designed experiments.