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 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
Wheat Growers, North Central Farmers Elevator Pursue Merger
CropLife 100Wheat Growers, North Central Farmers Elevator Pursue Merger
March 3, 2015
Two CropLife 100 retailers — South Dakota Wheat Growers (ranked No. 11) and North Central Farmers Elevator (No. 19) — have entered into a Letter of Intent to unify the two companies into a newly named cooperative. Read More
Growmark Group
CropLife 100GROWMARK In 2015: Back, To The Future
March 2, 2015
The nation’s third largest ag retail organization is simultaneously moving forward while remembering its past. Read More
CropLife 100Pinnacle Expands Sanders Brand In The South
February 27, 2015
Pinnacle has acquired Hopkins Seed and Chemical in Qulin, MO, which expands the company's Sanders brand to nine Southern states. Read More
CropLife 100Pinnacle Launches New Providence Agriculture Location In Indiana
February 27, 2015
Pinnacle Agriculture Holdings — ranked No. 6 on the CropLife 100 — has established a new retail location in New Castle, IN, which will operate as part of Pinnacle's Providence Agriculture brand. Read More
Carl Casale of CHS
CropLife 100Cooperative CHS Returns $518 Million To Owners
February 23, 2015
The 2015 cash return to owners is based on CHS net income of $1.1 billion, the company's second highest on record. Read More
Latest News
Industry NewsMonty’s Plant Food Expands Sales Team
March 27, 2015
Monty’s Plant Food Company, a leader in natural soil enhancement and  plant fertility products, has hired Andrew Bullock as a Read More
Crop InputsSyngenta Louisiana Plant Poised For 2015 Production
March 26, 2015
As the 2015 planting season gets underway, growers across the country will need crop protection products to combat pests and Read More
Lake Erie Nutrient Stewardship
LegislationOhio Lawmakers Finalize Phosphorus Restrictions
March 25, 2015
State lawmakers on Wednesday finalized new rules designed to curb toxic algal blooms on Lake Erie, calling the regulations a major step forward in addressing the problem. Read More
Spreaders17 Fertilizer Spreaders For 2015
March 25, 2015
Manufacturers shoot for versatility and accuracy in this year's crop of fertilizer spreaders. Read More
Industry NewsMonty’s Hires Mid-South Product Consultant
March 25, 2015
Monty's Plant Food Co. has hired Matt Woodring as a Product Consultant for portions of Central Kentucky and Tennessee.    Read More
StewardshipMapShots Integrates With DriftWatch
March 23, 2015
Growers and agricultural providers using AgStudio FARM and AgStudio PRO can now view vital information about specialty crops and apiaries through a recent integration with the DriftWatch Specialty Crop Site Registry from FieldWatch, Inc. Read More
Crop InputsWorld Health Organization Report Contradicts Scientific…
March 23, 2015
A new report from the World Health Organization has classified glyphosate with a “2A” rating as a probable carcinogen, a Read More
Eric SfiligojSeed Treatment Stays Necessary
March 20, 2015
Grower-customers looking to scale back spending in 2015 won’t consider seed treatment, say experts. Read More
HerbicidesMARCH MADNESS: Industry Rallies Around Glyphosate Safet…
March 20, 2015
A newly published report from the International Agency for Research on Cancer (IARC) classifies the herbicide glyphosate as a "2A-rated possible carcinogen" and the ag industry responds by circling the wagons. Read More
ManagementRetail Week: Precision survey, a technology acquisition…
March 20, 2015
Editors Paul Schrimpf and Eric Sflilgoj discuss recent travel, the upcoming precision adoption survey, and an unusual sighting at a 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
Crop InputsBioSafe Launching TerraGrow Soil Inoculant
March 20, 2015
TerraGrow is a blend of beneficial bacterial and fungal spores and nutrients carefully designed to promote healthier soil and crops. Read More
Winter Wheat
AdjuvantsMax Systems Debuts New Adjuvant NanoRevolution 2.0
March 18, 2015
Added to a tank mix of glyphosate at the conservative rate of two to four ounces per acre, NanoRevolution 2.0 has proven effective in killing resistant weed species that had already had up to two applications of the leading glyphosate product. Read More
Photo credit: United Soybean Board/the Soybean Checkoff
Seed/BiotechAgnition Launches Microbial Catalyst Seed Treatment
March 18, 2015
Agnition it has launched Commence for Soybeans, a microbial catalyst seed treatment for soybeans that stimulates microbial activity for healthier soil and a superior growth environment. Read More
4R Certified, Nutrient Stewardship Council,
StewardshipTyler Grain & Fertilizer Now 4R Certified
March 18, 2015
The 4R Nutrient Stewardship Certification Program has announced Tyler Grain & Fertilizer Co. in Smithville, OH, has been added to Read More
V.R. "Swede" Roskam
ManagementFormer MACA President V.R. ‘Swede’ Roskam P…
March 17, 2015
Former Mid America CropLife Association President V.R. “Swede” Roskam died unexpectedly in Wheaton, IL, on March 13, 2015 at the age of 85. Read More
corn field
Industry NewsNovaSource Announces Organizational Changes
March 17, 2015
Bob Gestring has accepted the position of Director of Sales, North America and Kyle Coleman has accepted a promotion to the role of Marketing Director, North America. Read More
Chuck Gates, Ohio CCA of the Year
ManagementOABA Honors 2015 Certified Crop Adviser Of The Year
March 16, 2015
Chuck Gates, of Tiffin, OH, has been named the 2015 Certified Crop Adviser of the Year by the Ohio Certified Crop Adviser Board and will receive $1,500 provided by DuPont Pioneer. Read More