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Mounting evidence shows overall insect abundances are in decline globally. Habitat loss, climate change, and pesticides have all been implicated, but their relative effects have never been evaluated in a comprehensive large-scale study. We harmonized 17 years of land use, climate, multiple classes of pesticides, and butterfly survey data across 81 counties in five states in the US Midwest. We find community-wide declines in total butterfly abundance and species richness to be most strongly associated with insecticides in general, and for butterfly species richness the use of neonicotinoid-treated seeds in particular. This included the abundance of the migratory monarch (Danaus plexippus), whose decline is the focus of intensive debate and public concern. Insect declines cannot be understood without comprehensive data on all putative drivers, and the 2015 cessation of neonicotinoid data releases in the US will impede future research. 

Abstract Innovations in precision agriculture now enable the identification of crop field patches whose retirement offers high environmental benefits and the low opportunity cost of crop yield loss. Precision conservation can lower costs to farmers and payment costs for government agencies. Precision conservation incentive policy should unite elements of land retirement (set-aside) and working lands policies that pay for environmental services. Key decisions surround how to bundle land fragments in a contract, keep contract design simple, evaluate environmental benefits, monitor compliance, and measure the additionality of those benefits. 

Prairie strips planted into crop fields offer multiple environmental benefits. This study estimates the willingness of U.S. farmers to convert 5% of their largest corn-soybean field to prairie strips in exchange for payment. Using stated preference results to estimate land supply, we find that 20% of farmers are willing to adopt prairie strips at payments equivalent to average Conservation Reserve Program (CRP) rental rates, corresponding to potential conversion of 90,000 acres on 1.8m acres of cropland. Farmers are likelier to adopt in smaller fields and when they perceive that prairie strips will benefit environmental quality or agricultural productivity. 

Conservation tillage in American soybean production has become increasingly common, improving soil health while reducing soil erosion and fuel consumption. This trend has been reinforced by the widespread adoption of glyphosate-based weed control systems. Many weed species have since evolved to resist glyphosate, reducing its effectiveness. We provide evidence that the spread of glyphosate-resistant weeds is responsible for significant reductions in the use of conservation tillage in soybean production. We estimate reduced-form and structural probit models of tillage choice, using a large panel of field-level soybean management decisions from across the United States spanning 1998-2016. We find that the first emergence of glyphosate-resistant weed species has little initial effect on tillage practices, though by the time that eight glyphosate-resistant weed species are identified, conservation tillage and no-till use fall by 3.9 percentage points and 7.6 percentage points, respectively. We further find that when ten glyphosate-resistant species are present, the predicted adoption rate of non-glyphosate herbicides rises 50 percentage points, and that the availability of non-glyphosate herbicides facilitates continued use of conservation tillage as glyphosate-resistant weeds proliferate. Using a simple benefits transfer model, we conservatively estimate that between 2008 and 2016 farmers' tillage responses to the spread of glyphosate-resistant weeds have caused water quality and climate damages via fuel emissions valued at nearly $245 million. This value does not account for climate damages due to carbon released during soil disruptions and is likely to grow as glyphosate resistance becomes more widespread and more farmers turn to tillage for supplemental weed control. 

Precision farming enables agricultural management decisions to be tailored spatially and temporally. Site-specific sensing, sampling, and managing allow farmers to treat a field as a heterogeneous entity. Through targeted use of inputs, precision farming reduces waste, thereby cutting both private variable costs and the environmental costs such as those of agrichemical residuals. At present, large farms in developed countries are the main adopters of precision farming. But its potential environmental benefits can justify greater public and private sector incentives to encourage adoption, including in small-scale farming systems in developing countries. Technological developments and big data advances continue to make precision farming tools more connected, accurate, efficient, and widely applicable. Improvements in the technical infrastructure and the legal framework can expand access to precision farming and thereby its overall societal benefits.