Bold et al. (2017) survey 312 small farmers in Uganda about their beliefs about urea fertilizer in the closest shop by asking respondents “to assess the quality of fertilizer on a scale of 1 to 10, where 0 means there is no nitrogen, 5 means that half of the official nitrogen is there, and 10 is the best possible quality”. Bold et al. find that farmers expect urea in their local shop to contain 38% less nitrogen than the manufactured standard; this means that farmers on average expect urea to contain 28.4% nitrogen by weight rather than 46%.

- Hoel et al. (2021) and Maertens et al. (2021) elicit farmer beliefs about fertilizer quality in Tanzania by asking farmers to think of their local market and “imagine that ten farmers from your village would visit agro-dealer shops in [this market] during the long rains season and each purchase 1 kg of fertilizer.” Then they ask, “If 10 farmers in your village purchase 1 kilogram of fertilizer at [this market] during the long rains season, how many would get good quality bags? They ask farmers how certain they are about their response. Hoel et al. find that 70% of farmers believe that some fertilizer in their local market is bad; on average, they believe that 34% is bad quality. Only 28% of the farmers believe that all fertilizer in their local market is good. They also report considerable uncertainty about these beliefs. Maertens et al. find that farmers believe that about 30% of fertilizer in their local market is bad.

- Ashour et al. (2019a) in Uganda also ask how many out of ten farmers who went to a local market to purchase fertilizer would buy bad fertilizer. They elicit the full distribution of beliefs – asking the maximum number of farmers that would purchase bad fertilizer and the minimum number. They divide the elicited range into eleven bins and provided farmers with 15 beans to distribute across the bins. Ashour et al. find that farmers believe that 35 percent of the fertilizer in their local market is of bad quality; but elicited distributions exhibit considerable uncertainty in this stated belief.<sup>23</sup> They find that 47% of farmers who purchased herbicides in the previous season reported believing that herbicides are often counterfeit or adulterated and 30% of farmers who had used mineral fertilizer reported believing that these fertilizers are often counterfeited or adulterated.

- Asante et al. (2021) asked both input dealers and farmers in Ghana to assess the quality of fertilizer in their district by estimating how many bags out of every ten bought and sold were good quality versus substandard quality. Researchers asked the question separately for commercial fertilizer and for fertilizer available through Ghana’s subsidy program. Input dealers proved more pessimistic than farmers. Based on their own experience, input dealers estimated that 45% percent of the commercial fertilizer was of bad quality and 31% of the subsidized fertilizer. Farmers reported that 28% of the commercial fertilizer in their district was likely substandard and 19% of the subsidized. And 47% of agri-dealers reported that fertilizer quality issues are among the most frequent complaints they receive from their customers.

> 23 Ashour et al. (2019a) also asked qualitative questions regarding how much of the fertilizer was likely counterfeit/adulterated: all of it, most of it, some of it, none.

17