Danish-Rodwick argues that once countries get a foothold in manufacturing, their productivity levels converge pretty quickly. But he says it takes much longer to do the same with agriculture. The reason you can get manufacturing convergence of productivity easily is that those are standardized technologies - usually part of international value chains. When it comes to agriculture in a completely different world, what counts is your soil, your pests, your climate conditions and crop varieties locally. And that's why technological diffusion in agriculture is much more complex.