US-IALE 2018

AUTHORS: Ashley E Larsen, UC Santa Barbara; Frederik Noack, University of British Columbia

ABSTRACT: Over the past 50 years, agricultural systems have become more simplified with fewer, high-yielding crops grown in shorter rotations on larger fields with less non-crop habitat interspersed. The trend towards simplified agricultural systems has undoubtedly led to increases in yields. Yet, there are concerns that more simplified agricultural landscapes result in increased use of pesticides and associated environmental degradation due to reduced natural enemy populations and more homogeneous crop resources. Here we elucidate how different aspects of landscape simplification at different spatial scales drive insecticide use. Using a fixed-effects panel data approach and unique data on crop production and insecticide use from over 100,000 field-level observations from Kern County, CA encompassing 2005-2013, we parse apart if and how crop diversity, field size and cropland extent affect insecticide use in practice. We show that the existence and magnitude of the effect of landscape simplification is strongly dependent on crop type and the proximity of surrounding agriculture to the focal field. These results indicate that neither the traditionally conceived ‘simplified’ nor ‘complex’ agricultural landscape is most beneficial to reducing insecticide inputs; reality is far more nuanced.