On the economic value of the agronomic effects of crop diversification for farmers.

This article investigates the effects of previous crops (pre crop effects) and crop acreage diversity on crop yields and chemical input uses, using a simultaneous equation modeling approach with farm-specific random parameters. Based on detailed farm-level data from 769 commercial farms in the Marne département of France (2008–2014), enriched with crop sequence, soil, and weather information, the study finds statistically significant positive effects of pre crops and crop acreage diversity on yield levels, but limited or no significant effects on chemical input uses, particularly fertilizers and pesticides. Farmers tend to select agronomically favorable crop sequences but generally do not adjust chemical input use according to pre crop benefits, possibly underestimating these effects or facing management constraints. Although crop acreage diversity is associated with modest yield increases and reductions in herbicide use, the economic benefits are limited, which may explain the persistence of specialized cropping systems despite policy incentives promoting diversification.