Investment is generally defined as activities that result in the accumulation of capital (Box 1) that yields a stream of returns over time. Thus, planting trees is typically considered an investment because it takes more than a year to generate a return, but applying fertilizer to a maize crop is not considered an investment because it generates a return during the current crop cycle. However, many investments by farmers are not made primarily or exclusively through financial outlays but through time spent, for example in clearing or improving land or in constructing farm buildings or irrigation channels.