work for different household members, _a f_ ( _K − K_ ). Taken together, these results show that gender norms around suitability of working with oxen lead to a concentration of household plot activities under men in the household, with women shifting to non-agricultural work.

One concern with the above heterogeneity analysis is the potential endogeneity of women’s involvement in oxen tasks. While we define this using endline data from control group households, the phase-in design means that many of these households also received the oxen and may have changed behaviors in response to treatment. With this in mind, we demonstrate the robustness of the heterogeneity results to using districtlevel differences in women’s decision-making power, shown in Figure 3, as an alternative construction of gender norms. Appendix Table B6 presents equivalent heterogeneity results using pre-program DHS data to characterize districts in the sample as either more or less conservative based on women’s decision-making power. Since, as discussed in Section 3.2, the two measures of district norms are highly correlated (0.75), this alternative way of analyzing heterogeneity correspondingly yields a similar pattern of results.

# **5 Conclusion and discussion**

In this paper, we provide experimental evidence on the short-term impacts of mechanization on household production and intra-household labor allocation among cotton farmers in Cˆote d’Ivoire. We find positive impacts on cotton production–a male-dominated cash crop–and intensification of agriculture, along with an increase in the value of complementary agricultural inputs used. Though our results are short-term and we do not detect a significant increase in household income in our survey time-frame, second season outcomes indicate that households expand their overall agricultural cultivation and not merely cotton. Moreover, our data indicates that animal traction can lead to yield–not just production–improvements, as farmers were able to increase their cotton production after land cultivation decisions were made.

Our results shed additional light on four stylized facts related to agricultural mechanization identified in observational studies. First, earlier observational studies analyzed by Pingali et al. (1987) suggested minimal yield gains for animal traction farms relative to hand-hoe farms. The increased cotton and rice production we detect in the first season, together with the fact that the oxen were distributed after land cultivation decisions were made, suggest that the oxen increased yields through either task quality or efficiency improvements during crop maintenance, harvest, and/or crop transport. Second, Pingali et al. (1987) documented a relationship between animal traction use and a larger area under cultivation. Our estimates indicate that this relationship is causal, with households who gain access to traction oxen bringing new land under cultivation. Third, earlier findings have suggested that additional area brought under cultivation as a result of mechanization was concentrated among market crops including cotton, rice, and groundnuts (Pingali et al., 1987). We find impacts concentrated among both cotton and rice but caution against the market crop characterization: few farmers in this setting report selling rice, suggesting that the impacts may stem from specific traction 16