Research
Publications
1) Risk-return trade-offs in diversified cropping systems under conservation agriculture: Evidence from a 14-year long-term field experiment in north-western India. European Journal of Agronomy (162).
Conservation agriculture practices are promoted to increase productivity, profitability, and sustainability across diverse cropping systems. Many studies have used these goals in decision support frameworks to identify the most effective treatment among those examined. While this approach is valuable, it lacks actionable guidance for farmers regarding maximizing return, while minimizing risk. It does not provide specific recommendations on how to allocate land across various cropping systems and tillage practices to achieve such objectives. This would require another long-term experiment exploring various combinations of treatments. To address this challenge, we propose the application of modern portfolio theory, specifically leveraging mean-variance and conditional value at risk optimization models. Using these models has enabled us to identify the optimal cropping system combinations with different tillage practices that maximized yield and net returns with minimal associated risk. The proposed approach allows for recommendations involving combinations of treatments that may not have been previously tested in a geography. In a 14-year long-term conservation agriculture study involving twelve combination of tillage and cropping systems, we showed how different combination of treatments differ in risk-return profile using mean-variance and conditional value-at-risk models that trace out a frontier of options—combinations of treatments that give highest returns at minimal risk. For example, we find that across risk neutral (most profitable) and most risk averse (lowest risk) farmers, the optimal treatments on the frontier encompass of maize-mustard-mungbean (MMuMb) under zero tillage and maize-wheat-mungbean (MWMb) under bed planting (which offer high returns and associated risk), maize-maize-Sesbania (MMS) under zero tillage (providing a balance of moderate returns and risk), and MMS under conventional tillage (yielding lower returns and risk). Additionally, risk-averse farmers stand to gain by diversifying their land allocation. For instance, they could allocate 54 % of their land to MMuMb under zero tillage and 46 % to MWMb under bed planting to target net returns of INR 1,32,000, with downside risk of INR 56,000, otherwise they can allocate 44 % and 56 % of their land to MMS under zero tillage and MWMb under bed planting, respectively, with a targeted net return of INR 1,22,000 and downside risk of INR 43,540. This highlights the nuanced trade-off between risk and return in maize based diversified cropping systems under different tillage practices. Leveraging mean-variance and conditional value at risk optimization models in the analysis of long-term experiments can yield novel treatment combinations that hold promise and can be recommended to farmers for implementation.
2) Closing the Gaps in Experimental and Observational Crop Response Estimates: A Bayesian Approach. Q Open.
A stylized fact of African agriculture is that crop responses to inorganic fertilizer application derived from experimental studies are often substantially greater than those from observational studies (e.g., surveys and administrative data). Recent debates on relative costs and benefits of expensive farm input subsidy programs in Africa, have raised the importance of reconciling these estimates. Beyond mean response differences, this paper argues for including parameter uncertainty and heterogeneity arising from variations in soil types, environmental conditions, and management practices. We use a Bayesian approach that combines information from experimental and observational data to model uncertainty and heterogeneity in crop yield responses. Using nationally representative experimental, survey, and administrative datasets from Malawi, we find that: (1) crop responses are low in observational data, (2) there are large spatial heterogeneities, and (3) based on sensitivity analysis, ignoring parameter uncertainty and spatial heterogeneity in crop responses can lead to questionable policy prescriptions.
3) Risk-based evaluations of competing agronomic climate adaptation strategies: The case of rice planting strategies in the indo-Gangetic Plains. Agricultural Systems 218 (2024): 104014.
Adjusting crop planting dates and variety durations is emerging as a crucial climate change adaptation strategy for many cereal systems. Such strategies include harmonizing crop planting with the onset of the rainy season or planting at specific recommended calendar dates. Evaluations of these strategies mostly consider yield and yield variability, but focus less on financial risks associated with different planting strategies and importance of risk aversion behaviour of the farmers in their decision to adopt the strategies. Here, we present a novel framework that uses a computational spatial ex-ante approach for risk-based evaluations of agronomic adaptation options. This framework allows development agronomic adaptation recommendations that consider climate risks for risk-averse famrers.
4) Good fences make good neighbors? Exploring potential transformative impacts of local governance towards livestock fence-in rights in Malawi. Outlook on Agriculture 2024.
Malawi's export earnings are dominated by tobacco, accounting for over 60% of export earnings. The demand for an alternative export commodity, pigeon pea, has been rising over the past decade, especially from India. In addition to their export potential, pigeon pea is an effective cover crop to protect soil heath and productivity in the dry season. They are mostly grown in southern region on very small farms, however, there are opportunities for expansion into central region given the existence of larger farms and agroecological suitability for the crop. Currently, social norms in the central region constrain this expansion. Livestock, and goats in particular, are left to roam free in the dry season by over two-thirds of farmers, relative to only one-third in the south. This leads to significant damage to pigeon pea crops and discourages farmers from growing them and taking advantage of the increased export demand. Much land is left bare and the few farmers that do grow crops during the dry season are forced to put up fences. This study assesses ex-ante implications, especially on agroecological transformation and economic growth, of shifting local governance arrangements among farmers around keeping livestock towards controlled systems. These externalities have been understudied in the development programming, yet their impacts are substantial, especially in lower-income countries. The policy solution under study is for the local government and non-state actors to support local governance arrangements through indirect payments to agroecosystem services. These can include information campaigns on benefits of controlled livestock systems, training and subsidizing modern goat house construction and feed preservation, and contract farming and product certification for adhering to acceptable community norms. Medium-term policy interventions include varietal development of adaptable short duration pigeon pea, initiating a review of the appropriate laws, and instituting more studies to understand these community norms.
5) Economics of Crop Residue Management. Annual Review of Resource Economics 2023.
More than five billion metric tons of agricultural residues are produced annually worldwide. Despite having multiple uses and significant potential to augment crop and livestock production, a large share of crop residues is burned, especially in Asian countries. This unsustainable practice causes tremendous air pollution and health hazards while restricting soil nutrient recycling. In this review, we examine the economic rationale for unsustainable residue management. The sustainability of residue utilization is determined by several economic factors, such as local demand for and quantity of residue production, development and dissemination of technologies to absorb excess residue, and market and policy instruments to internalize the social costs of residue burning. The intervention strategy to ensure sustainable residue management depends on public awareness of the private and societal costs of open residue burning.
6) Is wealth found in the soil or in the brain? Investing in farm people in Malawi. Review of Development Economics.
Should a typical developing country invest more in agriculture or education? At what stage of development is it optimal to invest more in each of these sectors? These are important questions that governments of developing countries grapple with when designing investment plans. In this paper, I propose a soil–human capital conceptual framework of development and use it to explain estimates of agricultural returns to schooling in Malawi. I use panel survey data for Malawi and rely on the exogenous education policy changes and spatial variation in access to schooling to identify effects of schooling on agricultural incomes. In addition, I correct for selection into income activities within a panel data and instrumental variables estimation framework. I find annual agricultural returns to schooling in Malawi of 3%–4% after correcting for selection and unobserved heterogeneity and 7% in the uncorrected specifications. I also find consistently higher returns to schooling in the nonagricultural sector for those not living in the village of birth and higher returns in the agricultural sector for those living in the village of birth. Given the size of the farm sector, wealth in Malawi is still in the soil, but that future growth in wealth depends on human capital investments.
7) Inter-district food flows in Malawi. Food Security, 2022. Ungated version.
Data on inter-district food flows are typically not collected and are thus unavailable for most sub-Saharan African (SSA) countries and for many parts of world. Given the volatile and frequent regionally specific deficits in food production in Malawi, evidence on food flows under different scenarios is needed for food policy decisions. This paper develops a spatially explicit mathematical programming model for the Malawian food sector to calibrate inter-district food flows and to assess how transport cost variations affect these flows. The food sector modeling approach we develop and implement allows for a natural estimation of inter-district trade flows in data sparse environments. In addition, we restrict crop mixes to those within the range of observed historical crop land use unlike modeling approaches that are prone to overspecialization. The calibration results for our baseline model indicate that about 7% of Malawian maize production flows between districts as compared to 66% for rice, 74% for beans, and 46% for groundnuts. A simulation experiment of varying unit transport costs shows that reductions in per unit transport costs increase the share of production that is traded inter-regionally, although the traded shares vary among the crops included in our model. The effectiveness of spatially targeted food production and marketing policies in Malawi therefore depends on these baseline food flows and the associated inter-district trade costs. Future research agenda on generating agricultural statistics in Malawi should focus on introducing intra-national commodity flow surveys.
8) Games of strategy in culture and economics research. Journal of Economic Methodology, 2020. Ungated version.
Games are meant to be fun, yet economists have successfully developed games that are less fun and less understood by participants especially in developing countries. This paper surveys failures in risk attitudes elicitation in sub-Saharan Africa (SSA) and questions the use of complex research tools such as multiple price list (MPL) approaches and behavioral games that rural participants have never played before. The failures can be avoided by using innovative research tools that ingest local activities like indigenous board games that the rural people have played for generations because these games are entertaining and closely related to the economic decisions they make. I provide a description of a variant of the indigenous strategic games of Africa- Mancala- and suggest a research agenda that applies the game in economics research—for risk attitudes elicitation, improving math skills of children and behavioral game theory.
9) Mancala board games and origins of entrepreneurship in Africa. PLOS ONE 2020, 15(10).
This study examines the correlational relationship between the historical playing of indigenous strategic board games (also called mancala) and the socio-economic complexity of African ethnic groups as well as the incidence of entrepreneurial pursuits. Anthropology literature suggests that these games may be associated with socio-economic complexity of the ethnic groups—the so-called games in culture hypothesis. I revisit this hypothesis with better data and motivated by anecdotal evidence, introduce a contemporary hypothesis, origins of entrepreneurship hypothesis—that descendants of societies that played complex mancala games are more likely to be engaged in non-farm self-employment today. I compile the first comprehensive database of mancala games in Africa matched to ancestral characteristics data, and for 18 African countries, to the Afrobarometer survey data. Using historical and contemporary data, I do not find evidence for either hypothesis. Despite the null results, I explore how related hypotheses and studies can build on the comprehensive mancala database.
10) Graphical analysis of agricultural spillover potential. Economics of Innovation and New Technology,2017, 17(6): 533-553.
This paper introduces two important extensions to the uncentered correlation metric, the commonly used metric proposed by Jaffe [1986. “Technological Opportunity and Spillovers of R & D: Evidence From Firms’ Patents, Profits, and Market Value.” The American Economic Review 76 (5): 984–1001] for analyzing research spillovers across firms or countries. First, it is shown that the Jaffe metric can be displayed graphically using the biplot, a graphical display of a two-dimensional approximation to any multidimensional matrix. Second, it is illustrated that since the data used to produce the Jaffe metric are constrained within the simplex (i.e. shares add up to one), then a theoretically superior metric satisfying the basic axioms of technological proximity measures in this sample space is the Aitchison distance measure, a metric based on log-ratios of shares. The findings of the paper using agricultural research and development spillover potential for Southern African countries show that the Jaffe metric overestimates the technological proximity across countries as compared to the proposed Aitchison measure.
11) Poverty-Lack of Access to Adequate Safe Water Nexus: Evidence from Rural Malawi. (with Charles Jumbe and Kenneth Wiyo). African Development Review ,2013, 25(4): 537-550.
This paper investigates the relationship between poverty and lack ofaccess to adequate safe water in rural Malawi.Data used in the analysis was collected from a survey covering 1,651 randomly selected households. We use Canonical Correlation Analysis (CCA) as a distinct technique for understanding the poverty–rural water access nexus. CCA results indicate that poverty in the context oflow income and expenditure is positively correlated with lack of access to safe and adequate water. Integrated Rural Water Resources Management (IRWM) interventions are therefore needed to address both challenges ofpoverty and poor access to adequate safe water in rural Malawi.
12) Comparative analysis of biofuels policy development in Sub-Saharan Africa: The place of private and public sectors. (with Charles Jumbe). Renewable Energy ,2013, 50: 614-620.
Considering that biofuels are considered as a catalyst for stimulating rural economic development, a number of countries in Sub-Saharan Africa (SSA) have developed policies to guide the development of the sector. This paper reviews the extent to which the existing biofuels policies and strategies of SSA countries have embraced public-private partnerships (PPPs) and whether the policies enhance or hinder such partnerships. In general, most SSA countries have no regulatory frameworks that have led to some private firms taking advantage of this inactivity to acquire large amounts of land for the growing of energy crops for biofuels at the expense of food crops, mostly involving smallholder farmers. The paper proposes developing effective PPP arrangements in order to leverage the synergies from the efficiencies of both public and private sectors. Such PPPs are crucial for mobilizing financial resources to drive scientific research and innovations for developing advanced processing technologies for second generation biofuels using lignocellulosic biomass as alternatives to traditional feedstock in order to foster the commercialization of biofuels in SSA. In conclusion, as we now live in a global village, countries must undertake detailed and systematic, country-specific assessments to ascertain the viability and feasibility of biofuels, and define the “rules of the game” in order to protect rural dwellers from loosing land to investors for growing energy crops and ensure equitable distribution of benefits of biofuels investments without posing a threat to environment or intruding on the rights of citizens or communities. Where biofuels are viable, PPPs should be part of the biofuels policy and investment strategy in order to build trust, collective responsibility and joint risk management to achieve shared outcomes for farmers, the investor and the environment.
Conference proceedings
Recent evidence suggests that there is a crop productivity growth slowdown in major crop production countries. Future changes in climate and land degradation further pose significant challenges for poor countries to increase crop productivity needed to feed the growing population. Intensifying crop production through genetics, inorganic and organic inputs, and irrigation therefore becomes a double-edged sword—needed, but potentially harmful to the environment. The increased availability of big data and Causal Artificial Intelligence (causal AI) methods, however, provide a unique opportunity for real time science to drive “smart” sustainable intensification through, for example, tailored agro-advisories that are differentiated by options and contexts, that are profitable, climate risk proof, budget conscious, and inclusive. In this paper, we analyze the trends in the spatial footprint of crop production practices across the globe to demonstrate the productivity slowdowns. We then propose an integrated framework for analyzing agricultural big data to allow for both increased productivity and sustainability. We conclude by proposing changes in the data ecosystem needed to drive the transitions including adaptive experiments and surveys, coupling of machine learning, crop growth models, and bio-economic agricultural sector models within an umbrella of Knowledge Guided Machine Learning (KGML), capacity development in agricultural data sciences, and inducing institutional innovations for big data and Causal AI to flourish including open data and code sharing in a FAIR-ER (Findable, Accessible, Interoperable, Reusable, Ethical, Reproducible) manner.
Working papers
- Whither broad or spatially specific fertilizer recommendations? (with Terry Hurley). Revise and Resubmit.
Are spatially specific agricultural input use recommendations more profitable to smallholder farmers than broad recommendations? Yes! This paper proposes a theoretical and empirical modeling procedure for determining the economically optimal spatial scale at which agricultural researchers can make soil fertility input use recommendations. Using geo-referenced on-farm fertilizer verification trial data from Malawi, we find evidence that spatially specific soil fertility input use recommendations for maize will always result in higher profits on average and even first order stochastically dominate broad recommendations in some site-years. This result holds generally for all stochastic profit functions that are non-decreasing and concave in both the optimal input use levels and the stochastic crop response parameters. We suggest several agricultural research policies including, (i) input supplier (fertilizer and seeds) provision of recommendations, (ii) more research directed towards heterogeneous environments and (iii) accounting of costs of agricultural research at different scales when making input recommendations.
2. Characteristics space analysis of agricultural technology adoption Dissertation Chapter 3.
There are always at least two sides to every story and an economic story of the adoption of agricultural technologies throughout sub-Saharan Africa (SSA) is no exception. One familiar story highlights the “acceptance problem,” namely that fundamental constraints in remoteness, weak markets, inappropriate policies, low education, cultural factors and many other related constraints are key drivers to the low rates of technology adoption that prevail in many parts of SSA. The other story focuses on the “availability problem,” which maintains that many newly available technologies fail to provide any relative advantage in terms of their performance related attributes compared with the other (often status quo) alternatives. This essay proposes a pure characteristics space analysis for both the acceptance and availability problems. We illustrate this model using an application of the adoption of maize varieties in Malawi, a rapidly changing differentiated input market. We find that farmers are willing to pay more for complex traits like drought tolerance and flint texture than yield differentials per se. Our results (and the analytical approach we develop) have direct implications for maize breeding programs in Malawi.
3. Behavioral game models for real-world games. Working paper.
Behavioral game theory has mostly relied on lab experiments using “simple games” developed by economists like beauty contest and centipede games. This is problematic because such games are complex for participants due to unfamiliarity and unrelated to real-world decision making. In this paper, I suggest a rethinking of the ideology and show that it is possible to use real-world games in behavioral game experiments. Using mancala heuristics—sowing games commonly played in Africa, I show that standard behavioral game theory models (level k and cognitive hierarchy) are inadequate to explain the more realistic multi-dimensional reasoning processes required in mancala.
Work in progress
- Meta Review of the “Conventional” Crop Varietal Use Evidence for Africa (with Phil Pardey). Presented at the SPIA-Gates Foundation Meetin g, Washington
- A Cautionary Political Economy Tale of Large Farm Registration in Malawi
3. Assessing the Inverse-Farm Size Productivity in Malawi. (with Fang Xia, Klaus Deininger, Daniel Ali and Henry Kankwamba). Presentation slides at the 2018 Annual World Bank Conference on Land and Poverty available here.
- Towards a theory of spatial organization of agriculture and land rights
- Incidence and productivity effects of abusus land rights: Evidence from Malawi
- Climate geoengineering impacts on global economic production (with Jay Coggins, Ben Kravitz, Ian Luby, Ibrahim Keita and Sinafikeh Germesa).
7. What do we know about (procured) input use in African agriculture (with Phil Pardey, Alison Joglekar,Connie Chan-Kang, Frikkie Liebenberg, Ian Luby, Senait Senay, Carlo Azzarri and Terry Hurley).
8.Sufficient Statistics, Exact Hat Algebra, and Differential Approaches in Economics.