Lidar on the Farm: 3D Elevation Data for Precision Agriculture

By Larry J. Sugarbaker and William J. Carswell, Jr. USGS Fact Sheet 2016–3088, December 2016.

Why terrain matters to farming

A founding motto of the Natural Resources Conservation Service (NRCS, once the Soil Conservation Service) is: "If we take care of the land, it will take care of us." Taking care of it starts with knowing its shape.

Lidar (light detection and ranging) produces digital elevation models (DEMs), from which computers work out a field's slope, aspect (which way it faces) and curvature. Those three values drive the NRCS Lidar-Enhanced Soil Survey (LESS) model, which draws soil boundaries more precisely and more objectively. DEMs, LESS outputs and similar data help the NRCS and other agencies conserve soil, wetlands and other resources.

The NRCS uses lidar to help farmers design farm ponds and contour farming. This lidar-derived elevation model shows field contours and several ponds. Image: NRCS.

Precision agriculture

Farms that know their soil type, wetness, drainage and the slope, aspect and curvature within each field can treat each part differently. J.R. Simplot, one of the country's largest private agribusiness companies, uses lidar for exactly that: placing seed, fertilizer, lime, pesticides and water where they are needed. The results are higher yields, better use of resources and less chemical use.

Treating a whole field the same way — the traditional approach for wheat, corn, soybeans and cotton — wastes fertilizer, pesticides and herbicides, and the excess can run off as pollution.

What it is worth

• Farm revenue: with lidar terrain data for all high-quality cropland, bigger yields and smaller crop losses are estimated to add $2 billion a year to farmers' revenue.
• NRCS services: lidar DEMs for all farmland would make the NRCS's farm assistance worth an estimated $79 million more each year.

Conservative annual national benefits of 3DEP data for farming and related uses:

Farmers and agencies use 3D elevation data for:

• prescription application of seed, fertilizer, water, pesticides and herbicides;
• farm pond and contour design;
• Tribal, State and local farmland programs;
• farmland suitability and drainage analysis, and conservation planning;
• mapping floodplains, cultural resources, wetlands, grasslands, forests and wildlife habitat.

The benefits include bigger crops, fewer losses to flooding or poor site design, better compliance in applying regulated chemicals, cheaper design of farm ponds and other infrastructure, and conservation of critical habitats.

The 3D Elevation Program

The 3D Elevation Program (3DEP) is a national USGS program that collects high-resolution elevation data and produces point clouds, bare-earth DEMs and other products. It grew out of a national assessment of lidar, IfSAR (interferometric synthetic aperture radar) and other elevation needs, and is now operational. The goal set in 2016 was complete quality level 2 (QL2) lidar for the conterminous United States, Hawaii and the U.S. territories, and IfSAR for Alaska, by the end of 2023.

Why a national program saves money and risk:

• Scale: acquiring larger areas cuts costs by about 25 percent.
• Planning: predictable federal investment lets Federal, State, Tribal, territorial and local partners plan ahead, and "buy up" to higher-quality data.
• Consistency: uniform national coverage works across project, jurisdictional and watershed boundaries and meets many needs at once.
• Simplicity: partners get contracts, published specifications and quality assurance, and can get on with their own work.
• Payoff: 3DEP can conservatively deliver $690 million a year in new benefits, with a potential of $13 billion a year across the economy.

The data

• Lidar quality: QL2 or better has a nominal pulse spacing of at most 0.7 meters and a vertical error of 10 centimeters (root mean square error, RMSEz). Data must be no more than eight years old. See the Lidar Base Specification.
• Alaska: statewide quality level 5 IfSAR, with a vertical error of 185 centimeters, plus digital surface models, intensity images and 5-meter DEMs.
• Products: classified point clouds and bare-earth DEMs with flattened water surfaces. Seamless national DEMs come at 1/3, 1 and 2 arc-seconds; the 1-meter DEM is seamless within each project.
• Access: everything is part of The National Map, free and without restrictions, including point-query services. Download from the National Map viewer.

Getting the most from 3DEP

Data a project needs may already exist in 3DEP, and ready-made products spare users the work of processing raw lidar. Where new data are needed, 3DEP offers pooled funding, vetted contractors, USGS contract management and quality inspection, the option to buy up, and sometimes cost-share funding.

Taking part: partners can fund USGS-managed acquisitions, receive cooperative funds to run their own (mainly through the Broad Agency Announcement), use USGS contracts, or contribute existing data that meet 3DEP specifications. See the 3DEP website or ask about contributing. Questions: 3DEP@usgs.gov.

Sources

Based on The 3D Elevation Program—Precision Agriculture and Other Farm Practices, by Larry J. Sugarbaker and William J. Carswell, Jr., USGS Fact Sheet 2016–3088, U.S. Geological Survey; a work of the United States government in the public domain. The NRCS elevation image and the benefits table are taken from the fact sheet's PDF; its tractor, yield and elevation images, courtesy of J.R. Simplot Company, are not reproduced. Benefit figures derive from Dewberry (2012). Any use of trade, firm or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.