Jordan Chamberlin

International Maize and Wheat Improvement Center | CIMMYT · Sustainable Agrifood Systems

Acid soils are widespread across sub-Saharan Africa. Agricultural lime can be used to alleviate production constraints associated with soil acidity, but lime is not widely available in the region, and it is unclear how profitable its use would be. To guide potential investments in lime market development, we estimated the profitability of acid soil...

Making a living from a small farm is difficult in sub-Saharan Africa. In this paper, we quantify how difficult, using a simple, robust, relation between per capita daily income from farming (FPDI), land per capita and whole-farm net profitability per hectare. This relation allows the calculation of the land area required to generate various levels...

This perspective paper draws heavily on the last chapter of the book 'Youth and the Rural Economy in Africa: Hard Work and Hazard' (Sumberg et al., 2021b), based on 10 years of field studies. It synthesises findings and sets out their implications for policy relating to youth, agriculture and rural development. Overall, our research lends support t...

Soil acidity is a major constraint to crop production in tropical regions. Although agricultural lime is one option to remediate acid soils, there is limited information on the potential returns on investments to liming by smallholders. Using survey data collected from 261 households in Rwanda, we estimated the crop-specific yield response to lime...

Ethiopia recently experienced a large-scale war that lasted for more than two years. Using unique High-Frequency Phone Survey (HFPS) data, which span several months before and after the outbreak of the war, this paper provides evidence on the immediate impacts of the conflict on households' food security. We also assess potential mechanisms and eva...

Monitoring smallholder agricultural productivity growth, one of the targets of the Sustainable Development Goals, rests on accurate measures of crop production and land area. Existing methods and protocols for measuring smallholder production and plot size are prone to various sources and forms of mismeasurement. Inaccuracies in production and land...

A regional geopolitical conflict and sudden massive supply disruptions have revealed vulnerabilities in our global fuel–fertilizer–food nexus. As nitrogen (N) fertilizer price spikes threaten food security, differentiated responses are required to maintain staple cereal yields across over- and underfertilized agricultural systems. Through integrate...

Early sowing of wheat has been proposed as an important crop management practice for reducing the threat of terminal heat stress – a threat which is likely to increase under climate change projections for the Indo-Gangetic Basin (IGB) of South Asia, home to more than 400 million people. However, to date there is little empirical evidence for the im...

Challenges of soil degradation and changing climate pose major threats to food security in many parts of the world, and new approaches are required to close yield and nutrition gaps through enhanced agronomic efficiency. Combined use of mineral fertilizers, organic inputs, improved germplasm and adaptation of these practices to local contexts throu...

We combine nationally representative data from Nigeria with spatiotemporal data from remote sensing and other sources to study how young migrants respond to observable characteristics of potential destinations, both in absolute terms and relative to origin locations. Migrants prefer destinations with better welfare, land availability and intensity...

Civil conflict began in Ethiopia in November 2020 and has reportedly caused major disruptions in access to health services, food, and related critical services, in addition to the direct impacts of the conflict on health and well-being. However, the population-level impacts of the conflict have not yet been systematically quantified. We analyze hig...

Vulnerabilities of the global fuel-fertilizer-food nexus have been revealed by a regional geopolitical conflict causing sudden and massive supply disruptions. Across over- and under-fertilized agricultural systems, nitrogen (N) fertilizer price spikes will have very different effects and require differentiated responses. For staple cereal productio...

We review the literature on the distribution of farm sizes in sub-Saharan Africa, trends over time, drivers of change in farm structure, and effects on agricultural transformation and present new evidence for seven countries. While it is widely viewed that African agriculture is dominated by small-scale farms, we show that medium-scale farms of 5 t...

Improving household resilience is becoming one of the key focus and target of social protection programs in Africa. However, there is surprisingly little direct evidence of the impacts of social protection programs on household resilience measures. We use five rounds of panel data to examine rural households’ resilience outcomes associated with par...

Smallholder agriculture in sub‐Saharan Africa is commonly characterised by high levels of technical inefficiency. However, much of this characterisation relies on self‐reported input and production data, which are prone to systematic measurement error. We show theoretically that non‐classical measurement error introduces multiple identification cha...

Crop yield estimation from satellite data requires field observations to fit and evaluate predictive models. However, it is not clear how much field data collection methods matter for predictive performance. To evaluate this, we used maize yield estimates obtained with seven field methods (two farmer estimates, two point transects, and three crop c...

We review the literature on the distribution of farm sizes in sub-Saharan Africa, trends over time, drivers of change in farm structure, and effects on agricultural transformation and present new evidence for seven countries. While it is widely viewed that African agriculture is dominated by small-scale farms, we show that medium-scale farms of 5 t...

While adoption rates for inorganic fertiliser are relatively high in Ethiopia, application rates are generally considered agronomically suboptimal. Using recent data on Ethiopian smallholder maize producers, we showed that maize response to nitrogen, and the profitability of fertiliser use depended on maize agronomy. The agronomic optimum ranged fr...

Smallholder farmers in Africa typically only have access to blanket fertilizer recommendations which are defined over very broad areas and may not be optimal for local production conditions. The response to such recommendations has generally been poor. Using a randomized control trial in Ethiopia, we explore whether targeted extension advice leads...

Crop yields across sub-Saharan Africa are much lower than what is attainable given the environmental conditions and available technologies. Closing this ‘ecological yield gap’ is considered an important food security and rural welfare goal. It is not clear, however, whether it is economically sensible for farmers to substantially increase crop yiel...

Maize yields can be improved through many individual technologies and management practices, but the full realization of potential benefits is generally understood to require integrated use of complementary practices. We employed two years of survey data and alternative econometric models to better understand the use of individual and bundled packag...

We use a unique dataset from Malawi that matches tenants and their landlord counterparts to document the role played by absentee tenants, i.e. tenants who reside outside the area where the rented land is located. We found that non-local tenants made up 22% of the tenants in our sample. A significant subset of them had higher off-farm income and sig...

Strategic planning for global agricultural R&D is hampered by a lack of comparable data on target populations. Surprisingly, even the global number of crop-specific farms are unavailable for any given year. We estimate the number of farms growing maize and wheat-the two most important cereals globally-at multiple geographic scales. For 2020, we est...

Scholarship on African land markets has proliferated in recent years. We contend that this scholarship consists of distinct literatures that examine non-overlapping parts of the system and diverge in their conclusions. Some studies view rising land markets as providing greater options for smallholder farmers and positive impacts on agricultural pro...

Maize production must increase three-fold in sub-Saharan Africa to meet the needs of future generations. Sustainably increasing maize production will require a portfolio of complementary technologies and policies. In this review we highlight four challenges to achieving this improvement. Improved nutritional density of maize in farmers’ fields and...

Agricultural statistics and applied analyses have benefitted from moving from farmer estimates of yield to crop cut based estimates, now regarded as a gold standard. However, in practice, crop cuts and other sample-based protocols vary widely in the details of their implementations and little empirical work has documented how alternative yield esti...

The expansion of agro-dealers into remote areas can be seen as conducive to more smallholders adopting new technologies and inputs, to include improved seed and fertilizer. However, lower travel costs may be offset by agro-dealer decisions on stocking and pricing, reflecting both travel time from wholesale markets as well as the level of competitio...

Rural development objectives are often framed relative to a targeted number of beneficiary farms and farm households. Yet the data available on the number and distribution of the world’s farms has been surprisingly fragmented and coherent estimates of the number of farms in a given region for a given year have not been available. We take a set of s...

Understanding yield responses to nutrient application is a key input for extension advice and strategic agricultural investments in developing countries. A commonly used model for yield responses to nutrient inputs in tropical smallholder farming systems is QUEFTS (QUantitative Evaluation of the Fertility of Tropical Soils). While QUEFTS has a stro...

Despite decades of investment in agricultural extension, technology adoption among farmers and agricultural productivity growth in Sub‐Saharan Africa remain slow. Among other shortcomings, extension systems often make recommendations that do not account for price risk or spatial heterogeneity in farmers' growing conditions. However, little is known...

This paper combines pre-pandemic face-to-face survey data with follow up phone surveys collected in April-May 2020 to examine the implication of the COVID-19 pandemic on household food security and labor market participation outcomes in Nigeria. To examine these relationships and implications, we exploit spatial variation in exposure to COVID-19 re...

We use nationally representative survey data from Zambia to evaluate whether rural youth out-migration is associated with a lack of rural economic vibrancy, as often asserted in policy discussion. After controlling for distance from markets, we do find some evidence that areas with more productive and market-oriented agriculture are associated with...

The establishment of secure and easily transferable land rights are a key component of rural development and poverty reduction strategies in many developing countries. In this paper, we use data on the Ethiopian land certification program to examine the impact of land certification on consumption expenditures of poor rural households in Ethiopia. W...

Intra-plot heterogeneity in yield is often observed in smallholder farming systems, although its implications for yield measurement remain under-investigated. Using a unique dataset on smallholder maize production in Ethiopia, we quantify the magnitude of inter-and intra-plot heterogeneity, describe the relationship between intra-plot heterogeneity...

Soil property and class maps for the continent of Africa were so far only available at very generalised scales, with many countries not mapped at all. Thanks to an increasing quantity and availability of soil samples collected at field point locations by various government and/or NGO funded projects, it is now possible to produce detailed pan-Afric...

We use recent plot‐level panel data from Tanzanian smallholder farmers to investigate maize yield responses to inorganic fertilizer under variable soil carbon conditions. Unlike many prior studies which consider total carbon measurements, we focus on active soil carbon, which is a component strongly related to key soil functions, such as nutrient c...

Credit markets are key instruments by which liquidity-constrained smallholder farmers may finance productive investments. However, the documented low demand and uptake of agricultural credit by smallholder farmers in sub-Saharan Africa pose challenges for energizing rural transformation in the region. In this paper, we investigate the impact of rai...

Soil property and class maps for the continent of Africa were so far only available at very generalised scales, with many countries not mappedat all. Thanks to an increasing quantity and availability of soil samples collected at field point locations by various government and/or NGOfunded projects, it is now possible to produce detailed pan-African...

Although still at incipient stages in most areas, agricultural land markets in sub-Saharan Africa (SSA) are growing rapidly. While the literature on the region’s land markets is expanding, there has been little attention thus far paid to the drivers of land rental prices. We know quite little about whether and how land markets and land contracts re...

We present an easily calibrated spatial modeling framework for estimating location-specific fertilizer responses, using smallholder maize farming in Tanzania as a case study. By incorporating spatially varying input and output prices, we predict the expected profitability for a location-specific smallholder farmer. A stochastic rainfall component o...

While much has been said in recent years about the importance of engaging rural youth in sub-Saharan Africa's development, the factual data about how African youth currently engage in rural economies remain sparse. We use recent nationally representative household survey data from six countries to describe the patterns of such engagement. We find t...

Local food prices are key indicators of food security and market conditions. Yet price data are often not available, particularly for rural areas of Sub-Saharan Africa. We compiled data from 168 markets to study spatial and temporal price variation. We found that prices slightly increase when the preceding growing season was dry. Across the contine...

While a considerable body of literature has developed in recent years around the drivers and consequences of rural out‐migration in sub‐Saharan Africa, relatively little work has been done to understand the impacts of migration into rural areas. We use nationally representative household survey data from Zambia to explore the relationship between r...

Given the marked heterogeneous conditions in smallholder agriculture in Sub‐Saharan Africa, there is a growing policy interest in site‐specific extension advice and the use of digital extension tools to provide site‐specific information. Empirical ex‐ante studies on the design of digital extension tools and their use are rare. Using data from a cho...

Low crop yields in Sub-Saharan Africa are associated with low fertilizer use. To better understand patterns of, and opportunities for, fertilizer use, location specific fertilizer price data may be relevant. We compiled local market price data for urea fertilizer, a source of inorganic nitrogen, in 1729 locations in eighteen countries in two region...

The original version of this article unfortunately contained the following errors.

Many African countries have recently experienced rapid growth in the numbers of medium- and large-scale farms. These developments have generated considerable speculation about the impacts of farmland concentration and inequality on smallholder households and communities. This study exploits inter-district variation in farm landholding patterns in T...

Ethiopia has achieved the second highest maize yield in sub-Saharan Africa. Yet, farmers’ maize yields are still much lower than on-farm and on-station trial yields, and only ca. 20% of the estimated water-limited potential yield. This article provides a comprehensive national level analysis of the drivers of maize yields in Ethiopia, by decomposin...

We estimate the efficiency and equity returns to farmland rental markets in Malawi using a matched tenant‐landlord survey of smallholder farm households in four districts. Our sample allows us to more fully observe the landlord side of the rental market which is almost always missing in previous studies. Our results suggest that land rental markets...

This paper is motivated by the consistent portrayal, within current policy discourse, of agriculture and the broader rural economy in Africa as domains of opportunity for rural youth. It presents a new conceptualization of landscapes of rural youth opportunity, where these landscapes reflect an individual’s reading of the complex interplay between...

Innovations to improve staple crop germplasm can reduce poverty and otherwise improve farmer livelihoods through complex and multiple pathways. This paper reviews the evidence for one prominent pathway—through increased incomes (in cash and kind) for poor farmers who adopt the technology. An important determinant of poverty reduction is the ability...

Traditional agricultural research and extension relies on replicated field experiments, on-farm trials, and demonstration plots to evaluate and adapt agronomic technologies that aim to increase productivity, reduce risk, and protect the environment for a given biophysical and socioeconomic context. To date, these efforts lack a generic and robust s...

We use three waves of nationally representative panel data from Tanzania to estimate the extent to which land rental markets provide a pathway for youth to enter into agriculture. We also investigate how transaction costs may impede youth access to renting-in land. Results suggest that rental markets are important mechanisms through which young far...

IPNI, ISRIC, CIMMYT, One Acre Fund, IITA, Wageningen Research & University