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Department of Food, Agricultural and Biological Engineering


Precision Agriculture Technology

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Precision Ag Technology Basics      4R Nutrient Stewardship Principles

Precision Ag Technology Introduction

Precision agriculture is a farming management concept based on observing, measuring and responding to variability in crops. These variabilities contain many components that can be difficult to compute and as a result technology has advanced to off-set these difficulties.  Two types of technology can generally be found within precision agriculture: those which ensure accuracy, and those that are meant to enhance farming operations.  By combining these two technologies, farmers are able to create a decision support system for an entire operation, thereby maximizing profits and minimizing excessive resource use. When utilizing precision agriculture technology, producers can become better stewards of the land by incorporating nutrient best management practices into their farming operation.

Tools to ensure accurate
  • Metering of inputs
  • Placement of inputs
  • Timing of inputs (influenced by environment)
Tools to enhance
  • Nutrient management planning and field execution
  • Field documentation/verification
  • Record keeping

Technology Example and Benefit


Guidance Systems

  • Reduce overlap
  • Accurate placement of inputs
  • Preserve conservation structures

There are two basic categories of guidance products: lightbar/visual guidance and auto-guidance. For lightbar/visual guidance, the operator responds to visual cues to steer the equipment based on positional information provided by a GPS. For auto-guidance, the driver makes the initial steering decisions and turns the equipment toward the following pass prior to engaging the auto-guidance mechanism. 

Variable Rate Technology

  • Accurate metering of inputs
  • Accurate placement of inputs
  • Preserve conservation structures

VRT consists of the machines and systems for applying a desired rate of crop production materials at a specific time (and, by implication, a specific location); a system of sensors, controllers and agricultural machinery used to perform variable-rate applications of crop production inputs.


Automatic Section Control

  • Reduce overlap
  • Accurate placement of inputs
  • Preservation of conservation structures

Turns application equipment OFF in areas that have been previously covered, or ON and OFF at headland turns, point rows, terraces, and/or no-spray zones such as grass waterways. Sections of a boom or planter or individual nozzles/rows may be controlled.


Crop Sensors/Remote Sensing

  • Accurate timing
  • Accurate placement of inputs
  • Presever conservation structures
Sensor technology refers to on-the-go optical sensors used to measure crop status. These sensors utilize an active LED light source to measure NDVI (Normalized Difference Vegetative Index) to predict crop yield potential. NDVI values reflect the health or “greenness” of a crop and can also provide a relative biomass measurement. Data collected from these sensors are being used to direct variable rate nitrogen applications in grain crops and plant growth regulator and defoliants in cotton.

Yield Monitoring/Mapping

  • Determine right amount, timing, source
  • Siting of new conservation structures

A yield-measuring device installed on harvest machines. Yield monitors measure grain flow, grain moisture, and other parameters for real-time information relating to field productivity.


4R Nutrient Stewardship Principles

The 4R nutrient stewardship principles are the same globally.  How they are used varies on field and site specific characteristics such as soil, cropping system, management techniques and climate. The scientific principles of the 4R framework include:

Essential nutrients, considering both naturally available sources and the characteristics of specific products, in plant available forms.

Assess and make decisions based on soil nutrient supply and plant demand.

Assess and make decisions based on the dynamics of crop uptake, soil supply, nutrient loss risks, and field operation logistics.
Address root-soil dynamics and nutrient movement, and manage spatial variability within the field to meet site-specific crop needs and limit potential losses from the field.