Profitability of fertilizer: Experimental evidence from female rice farmers in Mali

Intensified use of agricultural inputs, particularly fertilizer, is a possible route to improved agricultural productivity. Field trials of these technologies show substantial increases in yields, but typically are done on highly monitored experimental plots rather than by farmers themselves. Returns to a certain technology might be quite different on real-world farms than on experimental farms, particularly when farmers must re-optimize multiple inputs in response to a new technology. Suri (2011) argues that not all farmers benefit from fertilizer use, despite there being high average returns. Behavioral biases may also prevent farmers from realizing their intentions to use fertilizer (Duflo, Kremer and Robinson, 2011). We use a simple field experiment to provide free fertilizer to women rice farmers in southern Mali to measure how farmers choose to use the fertilizer, what changes they make to their agricultural practices, and the profitability of this set of changes. Rice is an important crop in the study area. It is almost exclusively farmed on women-controlled plots. The technology is low-input intensive and is “broadcast” farmed on non-irrigated flood planes: seeds are literally scattered loosely into a plot, rather than small plants transplanted from nurseries to rows in the plot. The rice production is mostly used for own consumption. Fertilizer is recommended by local agricultural extension agents and believed to substantially increase yields (Government of Mali, 2009). Nevertheless, only