Field Crop Sensors Determine In-Season Fertilization

Growers on the northern Plains continue to adopt precision agriculture technology and management practices.

In-field crop sensors are one of the new technologies farmers are using to help manage nitrogen fertilizer applications, particularly in corn and wheat. In-field sensors are used to apply variable rates of fertilizer across fields to maximize yields.

“This technology has the potential to increase yields by increasing nitrogen efficiency and, at the same time, protecting the environment,” says John Nowatzki, North Dakota State University Extension Service agricultural machine systems specialist. “For example, variable-rate fertilization gives farmers the option of decreasing nitrogen applications in areas with shallow aquifers, which reduces the potential for water contamination from nitrogen leaching.”

Crop sensors are mounted directly on the fertilizer application equipment and then coupled with variable-rate controllers. This allows farmers to vary fertilizer application rates to growing crops. Applying fertilizer to growing crops allows farmers to make split applications.

“In many cases, producers apply two-thirds of the recommended nitrogen fertilizer at or prior to planting and then apply the remainder as needed during the growing season,” Nowatzki says. “Farmers also can use in-field sensors to accurately estimate crop yield and get information they can use to make management decisions, such as whether or not to apply fungicides or insecticides. Crop sensors simplify the remote sensing process by transferring data directly to the computer on the tractor or fertilizer applicator in real time.”

Crop sensors function by measuring the amount of light waves that are absorbed and reflected by the plant leaves. The sensors estimate plant health and vigor by focusing light on plants and then comparing the amount of specific light waves that are absorbed by the leaves with other light waves that are reflected off the leaves.

The resulting comparisons are referred to as vegetative indices. The normalized difference vegetative index (NDVI) is the index most commonly used in remote sensing of agricultural crops. The NDVI compares the amount of red light absorbed by plants with the amount of near infrared light reflected off plants. Healthy green leaves absorb more red light than leaves that are lighter green.

Commercial in-field crop sensors use different methods to determine how much nitrogen fertilizer to apply in each area of a field. Some systems require farmers to apply ample fertilizer on a test strip in a field, which often is called a nitrogen-rich strip. The operator then drives over that area so the computer controller in the tractor can compare each area of the field with the nitrogen-rich strip.

Other systems recommend operating the sensors over representative areas of each field and making the rate decision based on average sensor readings.

Commercially available in-field sensors include Ag Leader’s OptRx, Topcon’s CropSpec, Trimble’s GreenSeeker and Holland Scientific’s Crop Circle. Each company has unique sensors, mounting techniques and methods of determining plant nutrient requirements. Current crop sensors focus on crop nitrogen needs.

Some companies recommend using one sensor for each 10-foot section of application width and mounting the sensors on the applicator booms, while others use only two sensors mounted on top of the tractor cab. The cost of each system ranges from $10,000 to $20,000.

“The results of in-field sensor research generally indicate that crop producers will use less nitrogen fertilizer to reach their goals,” Nowatzki says. “Farmers also can use this technology to advance management practices designed to maximize yields. In-field sensing technology complements in-season fertilization practices by allowing farmers to more accurately apply only the needed amount of fertilizer at each field location.”

Three NDSU Research Extension Centers are including in-field crop sensor presentations in their field day tours this summer. Nowatzki presented information on in-field sensor technology at the Hettinger REC field tour on July 10. Walt Albus, NDSU research agronomist at the Oakes Irrigation Research Site, will present similar information at the NDSU Agronomy Seed Farm field tour on July 16 and at the Williston REC field tour on July 24.

Leave a Reply

Precision Ag Stories
Precision AgGoogle Glass: New Tool For Ag
October 8, 2014
New wearable smart technologies such as Google Glass show potential to greatly impact how we accomplish the business of feeding the world. Read More
Precision AgPrecision Agriculture: Finding The Payback
September 6, 2014
Profitability in precision ag is not about any one technology, but the result of employing technology in a total system approach that is agronomically sound. Read More
Precision AgUAS: The S Stands For Smart, Service And Sensors
May 1, 2014
The only thing occuring more rapidly than the technologies’ evolution is the clamoring to implement UAS into agriculture as soon as possible. Read More
Precision AgAg Retail: 3 Tech Trends To Watch In 2014
April 1, 2014
It's been a busy first quarter of technology developments in 2014. Here are some of the highlights, and things to watch in the months ahead. Read More
Top 100 Articles
CropLife 100Pinnacle Agriculture Acquires Minnesota Retailer
April 14, 2015
Pinnacle Agriculture Holdings, LLC, ranked No. 6 on the CropLife 100,  has successfully acquired Liebl Ag, LLC in Ada, MN.  Read More
CropLife 100CHS, Aurora Cooperative Complete Fertilizer Storage, Grain Shuttle Loading Facility
April 13, 2015
CHS Inc., the nation’s leading cooperative and ranked No. 5 on the CropLife 100, and Aurora Cooperative (ranked No. 21) Read More
CropLife 100GROWMARK Acquires Missouri Refined Fuels Terminal
April 2, 2015
Bloomington, IL-based GROWMARK and Magellan Pipeline Co. have entered into an agreement in which GROWMARK will acquire the refined fuels Read More
CropLife 100Wilbur-Ellis Acquires South Dakota Retailer
April 2, 2015
Wilbur-Ellis Co.’s Agribusiness Division, a recognized leader in precision agriculture technology and the distribution and marketing of plant protection, seed Read More
CropLife 100The McGregor Co. Closes Smith-Kem Acquisition
April 2, 2015
The McGregor Co. — ranked No. 16 on the CropLife 100 list of largest U.S. ag retailers — has completed Read More
CropLife 100BRANDT Commemorates National Ag Day
March 20, 2015
The Illinois agriculture community gathered at BRANDT global headquarters on March 18 to celebrate National Ag Day behind this year's theme Sustaining Future Generations. Read More
Latest News
Industry NewsCHS Insurance Names New Director Of Sales
April 17, 2015
Bryan Lewis has been named director of sales for CHS Insurance, the nation’s largest agribusiness insurance broker and full-service insurance Read More
Mature Waterhemp in Corn
HerbicidesGenetic Literacy Project: There’s No Such Thing A…
April 17, 2015
Read the latest “analysis” on GMOs from Consumer Reports and you’ll “learn” that glyphosate, the chemical developed by Monsanto (its Read More
HerbicidesNew Resistance To 2,4-D Discovered In Australia
April 17, 2015
In a world-first case of herbicide resistance, researchers have confirmed that sowthistle weed in the south east of South Australia Read More
ManagementNews From RTP Company Visits and Growers Buying Older S…
April 16, 2015
Paul Schrimpf and Eric Sfiligoj discuss recent trips to the Research Triangle Park area and market seed sales trends. Read More
soybean field
StewardshipNew ASABE Standard Establishes Framework For Sustainabl…
April 16, 2015
The American Society of Agricultural and Biological Engineers (ASABE) has initiated a project to develop a new standard to establish Read More
MicronutrientsSouthern States: An Inside Look At Our Tissue Sampling …
April 15, 2015
Remember learning about the food pyramid in school? The nutritional diagram recommends the proper amount of nutrients you need on Read More
Industry NewsArysta Adds New U.S. Fungicides Marketing Manager
April 15, 2015
Arysta LifeScience North America recently hired Deneen Sebastian as its Marketing Manager for U.S. Row Crops, Fungicides. Most recently, Sebastian Read More
FungicidesVerdesian Launches Phosphite-Based Cereal Fungicide
April 14, 2015
A new, phosphite-based fungicide designed for improved suppression of deoxynivalenol (DON) in wheat and barley infected by Fusarium head blight Read More
Mature Waterhemp in Corn
HerbicidesSURVEY: Close To 90% Of Growers Battle Weed Resistance
April 14, 2015
Herbicide resistance management continues to be a priority for corn and soybean growers, and they’re working together more effectively to Read More
CropLife 100Pinnacle Agriculture Acquires Minnesota Retailer
April 14, 2015
Pinnacle Agriculture Holdings, LLC, ranked No. 6 on the CropLife 100,  has successfully acquired Liebl Ag, LLC in Ada, MN.  Read More
StewardshipFMC Corp. Joins Sustainable Agriculture Alliance
April 14, 2015
FMC Corp. has joined Field to Market: The Alliance for Sustainable Agriculture, a multi-stakeholder initiative working to define, measure and Read More
Industry NewsArysta Adds Two To Goëmar Sales Team
April 14, 2015
Arysta LifeScience North America recently announced two new additions to the Goëmar sales team: Steve Kelly, Technical Service Manager – Read More
Valley Variable Rate Irrigation
Precision AgVariable Rate Irrigation Gains Followers
April 14, 2015
Irrigation systems have had the ability to apply different amounts of water throughout a field for decades, using timers that Read More
CropLife 100CHS, Aurora Cooperative Complete Fertilizer Storage, Gr…
April 13, 2015
CHS Inc., the nation’s leading cooperative and ranked No. 5 on the CropLife 100, and Aurora Cooperative (ranked No. 21) Read More
Soybean field
Industry NewsThree Ag Co-ops Poised For Possible Merger
April 13, 2015
Following months of study and preparations, the Board of Directors for United Farmers Coop (UFC), Farmers Elevator Cooperative (FEC) and Read More
Eric SfiligojAgriculture Braces For More Belt-Tightening
April 13, 2015
Spring is in full bloom across the U.S. and ag retailers and their grower-customers are busily getting into high gear. Read More
ManagementPollinator Health and Washington, DC
April 9, 2015
CropLife America’s Kellie Bray speaks with CropLife Editor Eric Sfiligoj regarding bee health and proposed Beltway regulations. Read More
InsecticidesValent Takes On MGK Insecticide Portfolio
April 9, 2015
As of April 1, Valent U.S.A. Corp. became the exclusive provider of the MGK crop protection line of insect control Read More