This special issue brings together a selection of papers that not merely present agronomic research findings, but critically review orientations, methodologies and research practices in agronomy. The focus is on agronomic research as it conducted as component of rural development efforts in the global South or, in short, development-oriented agronomy. Aiming to contribute to development challenges like food security, human welfare and wellbeing, and environmental sustainability, a focus on development-oriented agronomy implies a step beyond a narrow understanding of agronomy as the science of crop production and soil management. Doing development-oriented agronomy forefronts the juggling with productivity enhancing, environmental and social developmental goals entailed when doing agronomy. What is more, development-oriented agronomy generally takes place within a complex environment of (inter)national research and development policy organisations, development donor-funded projects, governmental, NGO and private sector agencies and global professional networks and (public–private) partnerships. Consequently, development-oriented agronomy is a field where debate and contestations over goals and direction, research methodologies and findings of agronomic research are first likely to emerge and become apparent.

Changes in donor priorities have meant that agronomists working in the tropics find themselves in a fundamentally new operational space, one that demands rapid improvements in farmers' livelihoods resulting from the large-scale adoption of new technologies and crop management practices. As a result, on-farm trials in contemporary Agricultural Research for Development (AR4D) are increasingly implemented both to collect data and to spur farmer adoption. We examine the different interpretations and organisational practices of AR4D organisations in this new operational space, and reflect on the usefulness of on-farm trials for agricultural technology scaling. Three case studies are presented to address these questions – two in sub-Saharan Africa and one in South Asia. Each study is considered in light of Science and Technology Studies theory and locates science as a politically situated practice, recognising the tension that scientists face between providing evidence and persuading selected audiences. The case studies show that this tension results in the introduction of several biases that limit the scalability of the technologies under investigation. These include biases at the level of the trial location, host-farmer selection, trial design, management and evaluation. We conclude by discussing how the contemporary political and institutional environment of AR4D produces project beneficiaries and research outcomes on selected farms, but not necessarily impacts at scale.

In their recent paper ‘On-farm trials for development impact? The organization of research and the scaling of agricultural technologies’, de Roo, Andersson and Krupnik report on three case studies, each undertaken by one of the authors, of projects conducting on-farm research. They reach conclusions on the limitations of the projects themselves and the effects of ‘donor dependency’, and propose a strategy to overcome these issues. However, the description of the philosophy, strategies and conduct of the projects reviewed in the southern African case study is incomplete and misleading, and shows that the case study author did not understand or overlooked important project components. Due to this the conclusions reached, insofar as this case study is concerned, are largely either invalid or already contemplated in the project activities. Here, we describe more fully the philosophy and strategies followed by the series of projects on which the case study was conducted, which were designed to facilitate, through the upscaling of project methodologies, the eventual outscaling and widespread adoption of more sustainable farming systems by smallholder farmers in eastern and southern Africa. We propose these methodologies as a valid comprehensive approach to the organization of agricultural research for development for the successful development, scaling-up and scaling-out of agricultural technologies.

In their response to our paper on the problems of using on-farm trials in efforts to scale-out new crop production technologies and practices among smallholder farmers, Wall et al. (2019) focus on our descriptions of on-farm trials in just one of the three case studies of Agricultural Research for Development (AR4D) projects that were presented. They argue we did not understand the projects’ philosophy and that the biases in farmer and site selection we discussed, do not exist in the southern Africa case study.

Intended to test broad hypotheses and arrive at unifying conclusions, meta-analysis is the process of extracting, assembling, and analyzing large quantities of data from multiple publications to increase statistical power and uncover explanatory patterns. This paper describes the ways in which meta-analysis has been applied to support claims and counter-claims regarding two topics widely debated in agricultural research, namely organic agriculture (OA) and conservation agriculture (CA). We describe the origins of debate for each topic and assess prominent meta-analyses considering data-selection criteria, research question framing, and the interpretation and extrapolation of meta-analytical results. Meta-analyses of OA and CA are also examined in the context of the political economy of development-oriented agricultural research. Does size matter? We suggest that it does, although somewhat ironically. While meta-analysis aims to pool all relevant studies and generate comprehensive databases from which broad insights can be drawn, our case studies suggest that the organization of many meta-analyses may affect the generalizability and usefulness of research results. The politicized nature of debates over OA and CA also appear to affect the divergent ways in which meta-analytical results may be interpreted and extrapolated in struggles over the legitimacy of both practices. Rather than resolving scientific contestation, these factors appear to contribute to the ongoing debate. Meta-analysis is nonetheless becoming increasingly popular with agricultural researchers attracted by the power for the statistical inference offered by large datasets. This paper consequently offers three suggestions for how scientists and readers of scientific literature can more carefully evaluate meta-analyses. First, the ways in which papers and data are collected should be critically assessed. Second, the justification of research questions, framing of farming systems, and the scales at which research results are extrapolated and discussed should be carefully evaluated. Third, when applied to strongly politicized topics situated in an arena of scientific debate, as is the case with OA and CA, more conservative interpretations of meta-analytical results that recognize the socially and politically embedded nature of agricultural research is are needed.

Household surveys are one of the most commonly used tools for generating insight into rural communities. Despite their prevalence, few studies comprehensively evaluate the quality of data derived from farm household surveys. We critically evaluated a series of standard reported values and indicators that are captured in multiple farm household surveys, and then quantified their credibility, consistency and, thus, their reliability. Surprisingly, even variables which might be considered ‘easy to estimate’ had instances of non-credible observations. In addition, measurements of maize yields and land owned were found to be less reliable than other stationary variables. This lack of reliability has implications for monitoring food security status, poverty status and the land productivity of households. Despite this rather bleak picture, our analysis also shows that if the same farm households are followed over time, the sample sizes needed to detect substantial changes are in the order of hundreds of surveys, and not in the thousands. Our research highlights the value of targeted and systematised household surveys and the importance of ongoing efforts to improve data quality. Improvements must be based on the foundations of robust survey design, transparency of experimental design and effective training. The quality and usability of such data can be further enhanced by improving coordination between agencies, incorporating mixed modes of data collection and continuing systematic validation programmes.

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.

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.

Development actors, including the African Union, the Alliance for a Green Revolution in Africa and bilateral donors, promote a technology-driven sustainable intensification of agriculture as a way to feed a growing world population and reduce rural poverty. A broader view of smallholder agriculture in the context of rural livelihoods suggests that technological solutions alone are unlikely to meet these goals. Analysis of the solution space for agricultural interventions in a high potential area of southern Mali shows that intensification can lift most farm households out of extreme poverty and guarantee their food self-sufficiency. However, the most effective options do not fit the usual definition of sustainable intensification, increasing production per unit land while protecting the natural environment. Cropland expansion combined with the good yields seen in on-station experiments can nearly eliminate extreme poverty, while the biggest impact may come from taking advantage of peak seasonal prices for crops like groundnut. Other profitable alternatives can include meat production with small ruminants or sales of milk from cows. However, off-farm employment opportunities like gold mining outperform currently attainable agricultural options in terms of profitability. Options for rural households should fit within the households’ socio-ecological niches and respond to their priorities in order to be successful. Given the relatively low impact of (sustainable) intensification technologies alone, a rethinking of the role of agricultural research in development is needed in order to align interventions with farmer priorities and meet development goals.

Yield gaps have become a useful tool for guiding development-related agronomy, especially in the global South. While critics have challenged some aspects of the yield gap methodology, and the relevance of food security advocacy based on yield gaps, very few studies question the actual relevance, application and scalability of yield gaps for smallholder farmers (and researchers) in the tropics. We assess these limitations using two contrasting case studies: maize-based farming systems in Western Kenya and rice-based farming systems in Central Luzon, the Philippines. From these two cases, we propose improvements in the use of yield gaps that would acknowledge both the riskiness of crop improvement options and the role that yield increases might play within local livelihoods. Participatory research conducted in Western Kenya calls into question the actual use and up-scaling of yield measurements from on-station agronomic trials to derive estimates of actual and water-limited yields in the region. Looking at maize yield gaps as cumulative probabilities demonstrates the challenges of assessing the real magnitude of yield gaps in farmers’ fields and of deciding whose yield gaps count for agricultural development in Kenya. In the case of rice-based farming systems, we use a historical dataset (1966–2012) to assess changes in rice yields, labour productivity, gross margin and rice self-sufficiency in Central Luzon, the Philippines. While large rice yield gaps persist here, there appear to be few incentives to close that gap once we consider the position of crop production within local livelihoods. In this context, economic returns to labour for farm work were marginal: labour productivity increased over time in both wet and dry seasons, but gross margins decreased in the wet season while no trend was observed for the dry season. Since most households were rice self-sufficient and further increases in crop production would offer minimal returns while relying increasingly on hired labour, we question who should close which yield gap. Our case studies show the importance of contextualising yield gaps within the broader livelihood context in which farmers operate. We propose that this should be done at farm and/or farming systems level while considering the risks associated with narrowing yield gaps and looking into multiple performance indicators.

This paper follows the progress made in India for research and farmer adoption of conservation agriculture (CA) since the publication of Erenstein (2012), who contested the idea that zero-till (ZT) establishment of wheat in rice–wheat systems could be further developed into full CA systems. Data presented in this paper show that research has successfully found solutions for both the wheat and rice phases of the rice–wheat systems of the Indo-Gangetic Plains (IGP) in the past 8 years. It shows that by finding solutions in both the rice and wheat phases, yields, water use efficiency and profits increased, while labour needs reduced. Indian scientists have also confirmed these benefits in participatory on-farm research in various locations, both east and west regions of the IGP. Farmers see for themselves through experimentation that they get higher yields with less cost and with more efficient use of inputs and water. A key factor has been the development of improved seed drills with the help of Indian private sector manufacturers of agricultural equipment. Indian scientists have also successfully conducted CA research on several other crops and in other regions besides the IGP. The paper shows that it is better to introduce parts of the CA management practices in a step-wise fashion first, rather than introducing the entire package at once since farmers first have to test and evaluate a new technology to understand how it benefits them personally before they will adopt it. The paper concludes that in the rice–wheat systems of South Asia, adoption of CA is indeed possible to achieve although it is still a work in progress. CA is a complex technology package and it takes time to overcome all of the contested issues mentioned in Erenstein (2012).