Figure 3. (a) Alley cropping experiments in the Peruvian Amazon with upland rice flanked by perennial ice-cream bean (Inga edulis). Note the straight lines and uniform spacing of rice in the middle and, the the uniform distribution of Inga trimmings in (b). Controlled experiments like these were (and still are) the rule on agricultural research stations in the tropics, yet they fail to replicate the haphazard conditions in farmer’s fields.