Crop Cover Database Seeds Local Environment Coverage

The U.S. Department of Agriculture’s Cropland Data Layer database distinguishes more than 100 crop categories with data back to 2008, which can be overlaid with other variables. Photo: Susanne Nilsson via Flickr Creative Commons (CC BY-SA 2.0).

Reporter’s Toolbox: Crop Cover Database Seeds Local Environment Coverage

By Joseph A. Davis

A lot of environmental stories begin with agricultural cropland. They may be about water (drainage, irrigation), climate (rain, drought, heat, cold), chemicals (fertilizers, pesticides) or more.

But if you want to generalize, you need data. So it’s a good thing the U.S. Department of Agriculture’s National Agricultural Statistics Service each year puts out its National Cropland Data Layer.

Or at least it did, or has been, pending the Trump USDA cuts and relocation. Already, many employees of the statistics service have been working out of regional offices, but these are slated to be cut in number from 12 to five.

You can access the cropland data layer by taking a quick look from here.

 

Where the data comes from

The data comes from satellites: namely Sentinel-2, Landsat 8 and Landsat 9. It’s all explained in the very thorough documentation that accompanies the database. The resolution of the CDL maps is 10 meters.

 

The resolution of the maps is

10 meters. Quality-wise, that’s

about as good as data can get.

 

Quality-wise, that’s about as good as data can get. But it’s not perfect — as NASS itself meticulously points out in the documentation. It estimates its reliability in the range of 80%.

How, for example, do you represent an acre planted in winter wheat followed by soybeans? NASS itself goes through an elaborate and extensive groundtruthing process. So you know.

The CDL database distinguishes more than 100 crop categories. In the present form, the annual data goes back to 2008.

It’s presented online through an interactive map-formatted viewer called CroplandCROS, so you can zoom in to areas of interest and select layers or even time sequences (as animations).

There are also the Cropland Data Layer Viewer and some others. Alternatively, you can download the entire dataset. (Note: The full data download feature appeared not to be working at the time of this writing. The wreckage of the USDA may already have started.)

 

How to use the data smartly

Just one word (to adapt a phrase from “The Graduate”): layers.

 

What about crop cover?

Layers allow you to explore how

crop cover relates to other variables.

 

In other words: what about crop cover? Layers allow you to explore how crop cover relates to other variables.

Ask this: What pesticides are used on a particular crop? Or this: How is this year’s drought affecting corn? Or how runoff from the Mississippi River basin croplands affects the nutrient runoff that produces Gulf of Mexico dead zones. Farmers and traders, nonetheless, may use it to predict the price of wheat.

And so forth. The possible uses may be limited only by your imagination.

As with all environmental databases used in journalism: Build your reporting on non-cyber information sources. Talk to farmers and commodity brokers. And like this USDA satellite data service, groundtruth everything you can.

[Editor’s Note: See additional Reporter’s Toolboxes for insight on another U.S. land cover database and on the U.S. Census of Agriculture, as well as Features on a global land cover dataset and how one reporter used it to ID tensions between food production and biodiversity. Plus, for more on covering agriculture as an environmental story, see our Topic on the Beat: Agriculture page, with additional agriculture stories from SEJournal and agriculture headlines from EJToday.]

Joseph A. Davis is a freelance writer/editor in Washington, D.C. who has been writing about the environment since 1976. He writes SEJournal Online's TipSheet, Reporter's Toolbox and Issue Backgrounder, and curates SEJ's weekday news headlines service EJToday and @EJTodayNews. Davis also directs SEJ's Freedom of Information Project and writes the WatchDog opinion column.

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* From the weekly news magazine SEJournal Online, Vol. 10, No. 35. Content from each new issue of SEJournal Online is available to the public via the SEJournal Online main page. Subscribe to the e-newsletter here. And see past issues of the SEJournal archived here.