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DIME Seminar: When does information make a difference? A field experiment with farm-specific soil information in Tanzania

March 12, 2019

MC 7-860

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  • Low use of mineral fertilizers by small scale farmers in sub-Saharan Africa contributes to low crop yields, high rates of food insecurity, and persistent poverty.

    This paper focuses on a possible explanation as yet unexplored in the literature for persistently low rates of fertilizer adoption: local variation in soil quality means that blanket fertilizer recommendations set by regional governments may be wrong for many farms. We use a randomized control trial providing farmers with plot-specific soil testing and fertilizer recommendations (with and without a concomitant easing of farmer liquidity constraints) to observe effects on investment and crop yields. We find evidence of important within-village variation in soil nutrient deficiencies; we also find that government-issued fertilizer recommendations are not relevant for the majority of farmers in our sample.

    Results demonstrate that a combination of liquidity and information is key to resolving plot-specific soil nutrient limitations; information alone does not change investment, and provision of vouchers without accurate information leads farmers to purchase the most common fertilizer in the market, rather than the best formulation for their needs. Results from a production function analysis show that application of mineral fertilizer to address plot-specific nutrient limitations leads to large maize yield increases. Our research suggests that substantive crop yield increases in the region will require a targeted approach that addresses sub-regional soil limitations in combination with economic constraints.

     

     

     

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    HOPE MICHELSON

    Assistant Professor

    Hope Michelson studies the dynamics of poverty and food security in low-income countries where market failures are a fact of life. One of her key subjects is the interaction of international development efforts with local and large-scale agribusiness. She investigates how small farmers respond to the expansion of international supply chains, the sourcing of agricultural products, and the buying and selling of agricultural inputs.

  • DIME is a World Bank-wide program to generate knowledge on the effectiveness of development policies. Working across 18 thematic areas, DIME collaborates with 300 agencies in 72 countries to improve the effectiveness of policies and programs and strengthen country capacity for real-time evidence-based policy-making. More »

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