inputs according to variation in prices and productivity impacts or if various constraints better explain the considerable heterogeneity we observe among and within regions intra-nationally.

# **_4. There is surprisingly low correlation between the use of commonly “paired” modern inputs at the household- and, especially, at plot-level._**

Since many of the modern inputs we study have positive interaction effects agronomically, are sold together at input retail shops, and/or are provided in bundles through government subsidy programs, one might reasonably expect farmers to use modern inputs together in packages. The LSMS-ISA data allow us, for the first time, to uncover to what extent a large sample of farmers exploits known complementarities. In general, we find that even when households pair modern agricultural inputs together on farm, at the plot level, there is very little correlation in modern inputs use. For example, only 4 percent of Ethiopian agricultural households use inorganic fertilizer use, improved seed, and irrigation on-farm, and far less than 1 percent use all three on the same plot. Because biophysical complementarities only arise when inputs designed to be used together are combined on the same plot, this implies that households are spreading inputs across plots rather than concentrating them on single plots. This behavior has gone largely unstudied to date and raises important questions about prospective untapped productivity gains from coordinated modern inputs use. <mark>This finding has implications for extension programs and policies aimed at promoting efficient input use.</mark>

**_5. Maize-dominated plots exhibit higher rates of input use intensity, even relative to plots planted with cash crops._**

In general, modern input use rates are higher on plots where maize is the dominant crop than on plots dedicated primarily to other species. Moreover, plots that include a major cash crop – less than one quarter of the total observed – are generally no more likely to receive modern agricultural inputs of any sort. In particular, average fertilizer application rates are higher on plots where maize is grown than on ones where it is not, and the presence of maize accounts for nearly two-thirds of the explained intra-farm variation among plots in fertilizer application rates. And 25-40 percent of maize cultivating households purchased new maize seed in the last main agricultural season. In the few places where we observe full improved seed variety statistics, nearly one-quarter of maize cultivating households in Ethiopia and over half in Malawi used an improved variety in the main growing season. These findings suggest more widespread participation of African agricultural households in modern input distribution systems than has been widely recognized. The weight of the evidence suggests that maize may be “on the move” in Africa.

**_6. There exists a consistent inverse relationship between farm or plot size and input use intensity._**

<mark>A longstanding agricultural development literature on the inverse relationship between farm size and crop yields suggests that input use falls off with farm size. We corroborate that latter pattern and find that it is robust even to controlling for farm-level effects and for possible self-reporting bias that can be corrected using GPS measurement of plots. Indeed, the inverse relationship is, perhaps surprisingly, stronger at the plot level than at household level in virtually all cases. The</mark> 51