Finally, constructing a sensible proxy for the recall length of fertilizer input has some of the same challenges as for labor. However, the application of fertilizer input covers shorter periods than the more continuous task of working on the plot. In Malawi IHS4 and IHPS 2016/17, we use the recall length to planting (equation (2)) when analyzing input use in the full sample (that is, both plots on which fertilizer was used and plots on which it was not used). When assessing fertilizer quantity reporting among plots receiving fertilizer, we can instead use the recall length to the first application of fertilizer on the plot. Fertilizer application is reported in weeks after planting the plot but transformed to months for the purpose of the recall variable. Since fertilizer application happens after planting, the recall length for fertilizer is shorter than for planting: In Tanzania NPS 2012/13, we once again use recall length to planting (equation (3)), lacking information on fertilizer application timing.

All recall variables are coded in increments of one month as this is the unit in which harvest, planting, and other dates are recorded in the data. The various recall variables vary in length between and within surveys. Recall length to end of harvest ranges from 2 to 18 months in Tanzania NPS 2012/13 (mean: 9.2), 0 to 13 months in Malawi IHS4 (mean: 8.9),<sup>6</sup> and 3 to 12 months in Malawi IHPS 2016/17 (mean: 5.7; Table 3; Figure 1).

Recall length to planting varies between 7 and 25 months in Tanzania NPS 2012/13 (mean: 14.7) and between 4 and 18 months in Malawi IHS4 2016/17 (mean: 13.4), though there are very few observations with a recall length shorter than 9 (Figure 1). In Malawi IHPS 2016/17, the range of recall length varies between 4 and 9 (mean: 5.7; Table 3). Most of the outcomes of interest which we analyze using recall length to beginning of season were collected during the first visit. The two-visit structure thus cuts the average recall length to beginning of planting to 5.7 months, relative to 13.4 (Malawi IHS4 2016/17 cross section) and 14.7 months (Tanzania NPS 2012/13). Recall length to first fertilizer application is minimally shorter than recall length to planting, suggesting most farmers start fertilizing quite soon after they finish planting (Figure 1; Table 3).

Since this analysis exploits variation in the timing of Tanzania NPS 2012/13 and Malawi IHS4 fieldwork, rather than explicitly randomizing by recall length to agricultural activities of interest, the data are not evenly spread across time and space (Figure 1). This is the case because, while the interviews are spread across 12 months, not all interviewed households are agricultural households and agricultural activities vary at the household or cluster level. Households also differ on observable characteristics over time, many of which are likely correlated with the outcomes of interest. To address this issue, we introduce a set of control variables. These fall into the following categories: regional and enumerator dummies, respondent characteristics (e.g. gender, age, education, whether respondent is plot manager), household characteristics

> 6 There are three cases of a recall length to harvest end of zero months, which implies that in these cases farmers have finished their harvest within the month of being interviewed. This scenario can realistically occur in Malawi IHS4 because farmers are asked to identify the last rainy season completed, and the agricultural questionnaire is administered in reference to that season. The agricultural season spans a period of November to April and the three cases at hand are from households interviewed in April of 2016, so that it is very plausible that these farmers finished harvesting just before the interviews took place.

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