Satellite detection of cover crops and their effects on crop yield in the Midwestern United States

Abstract

Supplementary material for this article is available online Corrigendum AbstractThe original raw dataset used to generate this work contained a number of duplicate entries-roughly 7% of the total farm fields. The substantive majority of these were from one large farm that had conducted their operations in a way that caused duplication as a side effect in our data generation process. Unfortunately, as the error was in the raw dataset, its correction required a re-run of the entire data pipeline, resulting in numerous small downstream changes. With respect to the most important numbers, the accuracy of the classifier went down slightly from 91.5% to 91.2% measured in absolute terms but increased from 0.68 to 0.74 measured by kappa. The trend in cover cropped acres grew slightly stronger, and the yield effects in maize and soybean moved from 0.65% to 0.71% and 0.35% to 0.29% respectively. None of the overall conclusions of the work have materially changed. Below, we provide all changes to the applicable sections of the original manuscript in bold underscore (or strikethrough) where applicable, in addition to modified versions of the corresponding figures and supplementary materials. OPEN ACCESS RECEIVED AbstractThe practice of planting winter cover crops has seen renewed interest as a solution to environmental issues with the modern maize-and soybean-dominated row crop production system of the US Midwest. We examine whether cover cropping patterns can be assessed at scale using publicly available satellite data, creating a classifier with 91.5% accuracy (.68 kappa). We then use this classifier to examine spatial and temporal trends in cover crop occurrence on maize and soybean fields in the Midwest since 2008, finding that despite increased talk about and funding for cover crops as well as a 94% increase in cover crop acres planted from 2008-2016, increases in winter vegetation have been more modest. Finally, we combine cover cropping with satellite-predicted yields, finding that cover crops are associated with low relative maize and soybean production and poor soil quality, consistent with farmers adopting the practice on fields most in need of purported cover crop benefits. When controlling for invariant soil quality using a panel regression model, we find modest benefits of cover cropping, with average yield increases of 0.65% for maize and 0.35% for soybean. Given these slight impacts on yields, greater incentives or reduced costs of implementation are needed to increase adoption of this practice for the majority of maize and soybean acres in the US.

Mapping twenty years of corn and soybean across the US Midwest using the Landsat archive

“…Since 2008, the confluence of Landsat and other satellite imagery, training data from the Farm Service Agency, and scalable machine learning algorithms has enabled the United States Department of Agriculture (USDA) to create the Cropland Data Layer (CDL), which maps 108 crop types at 30 m spatial resolution across the 48 conterminous US states 2 . While it was created primarily to aid the USDA's annual crop area estimates, CDL has enabled a multitude of downstream research and operational work in the past decade 3 , chief among them forecasting food production 4 , monitoring crop yields [5][6][7][8][9] , identifying agronomic practices [10][11][12][13][14][15][16][17] , and assessing ecological impacts [18][19][20][21][22][23] .…”

The hidden land use cost of upscaling cover crops

“…Cover crops are commonly included in strategies aimed at increasing the sustainability of agricultural production systems. Their environmental and societal benefits include improved soil retention [1], weed control [2], soil physical properties [3], carbon sequestration [4], biocontrol services [5], water quality [6], and nutrient cycling [7,8]. Universities, nonprofits, and industry are all now working to achieve wider adoption of cover crops through a mixture of research, advocacy, education, and outreach [9].…”

Satellites reveal a small positive yield effect from conservation tillage across the US Corn Belt

“…Previously published yield maps for maize and soybean were produced using the Scalable Crop Yield Mapper (SCYM) [33], a satellite-based approach with a demonstrated ability to detect impacts from management practices [47,48]. This approach has two main steps.…”