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Precision, Geospatial, & Sensor Technologies

Title Summary Date ID Author(s)
Interpreting Yield Maps - "I gotta yield map - now what?"

Yield monitors are the first step many producers take into the age of precision farming. While their cost is reasonable, the commitment of time and resources required to effectively use this technology is significant. A yield monitor, combined with Global Positioning System (GPS) technology, is simply an electronic tool that collects data on crop performance for a given year. The monitor measures and records information such as crop mass, moisture, area covered, and location. Yield data are automatically calculated from these variables.

May 1, 2009 442-509
Investing in GPS Guidance Systems?

The price of GPS (Global Positioning Satellite) guidance system technology continues to decline as its capabilities increase. Many farmers question if or when they should invest in this technology. The major advantage of using GPS is input savings from more precise field application of seed, fertilizers, chemicals, fuel, and labor, as well as increased benefits to the farm production process (extended working time, reduced fatigue, etc.).

May 26, 2009 448-076
Precision Farming Tools: GPS Navigation

For a review of the principles of GPS to locate specific field points, refer to this GPS Tutorial (Trimble Navigation Limited, 2008). GPS and associated navigation systems are used in many types of agricultural operations. These systems are useful particularly in applying pesticides, lime, and fertilizers and in tracking wide planters/drills or large grain-harvesting platforms. GPS navigation tools can replace foam for sprayers and planter/drill-disk markers for making parallel swaths across a field. Navigation systems help operators reduce skips and overlaps, especially when using methods that rely on visual estimation of swath distance and/or counting rows. This technology reduces the chance of misapplication of agrochemicals and has the potential to safeguard water quality. Also, GPS navigation can be used to keep implements in the same traffic pattern year-to-year (controlled traffic), thus minimizing adverse effects of implement traffic.

May 1, 2009 442-501
Precision Farming Tools: Global Positioning System (GPS)

Precision Farming. Modern agricultural management practices are changing from assuming homogenous fields to attempting to address field variability by dividing the field into smaller zones and managing these zones separately. Precision farming can be defined as the gathering of information dealing with spatial and temporal variation within a field and then using that information to manage inputs and practices (Precision Farming: A Comprehensive Approach, Virginia Cooperative Extension (VCE) publication 442-500). Precision farming is made possible by linking computers, on-the-go sensors, Global Positioning Systems (GPS), and other devices. This publication discusses GPS principles and the technology that makes it possible.

May 1, 2009 442-503
Precision Farming Tools: Soil Electrical Conductivity

Soil electrical conductivity (EC) is a measurement that correlates with soil properties that affect crop productivity, including soil texture, cation exchange capacity (CEC), drainage conditions, organic matter level, salinity, and subsoil characteristics. This publication discusses: 1) How, with field verification, soil EC can be related to specific soil properties that affect crop yield, such as topsoil depth, pH, salt concentrations, and available water-holding capacity; 2) Soil EC maps often visually correspond to patterns on yield maps and can help explain yield variation; and 3) Other uses of soil EC maps (Table 1), including developing management zones, guiding directed soil sampling, assigning variable rates of crop inputs, fine tuning NRCS soil maps, improving the placement and interpretation of on-farm tests, salinity diagnosis, and planning drainage remediation.

May 1, 2009 442-508
Precision Farming Tools: Variable-Rate Application

There are a number of questions that must be answered before establishing a site-specific crop management (SSCM) program. Many of these questions are economic, some are agronomic and environmental, and others are technology-related. This publication is intended to discuss variable-rate devices that are available, while providing an understanding of which technologies might best fit a cropping system and production management strategy.

Aug 1, 2011 442-505
Precision Farming Tools: Yield Monitor

Using yield monitors is the first step many producers take in precision farming (Precision Farming: A Comprehensive Approach, Virginia Cooperative Extension (VCE) publication 442-500). A yield monitor, combined with Global Positioning System (GPS) technology, is an electronic tool that collects data on crop performance for a given year. The yield monitor for grain measures and records information such as grain flow, grain moisture, area covered, and location. Yields are automatically calculated. Yield monitors also are available for commodities such as peanuts, cotton, forage silage, and sugar beets. These monitors have some elements in common with grain-yield monitors. While the cost of a yield monitor is reasonable, the commitment of time and resources required to effectively use this technology can be significant.

May 1, 2009 442-502
Precision Farming: A Comprehensive Approach

Precision Farming (PF), also referred to as precision agriculture or variable rate technology, is the process used to vary management of crop production across a field. Midwestern farmers have been using PF technologies for several years and it is now becoming popular in Virginia. This publication introduces the principles and terminology used in PF. Crop producers can use this information to gain a working knowledge of PF and develop the ability to implement PF technologies in traditional crop production.

May 1, 2009 442-500
The Virginia GIS County Data Series

The Virginia GIS (geographic information system) County Data Series is part of an effort by the Virginia Geospatial Extension Program to facilitate increased awareness of and access to geospatial products and services by educators, local governments, state agencies, and other entities. This extensive collection of GIS data provides some of the most up-to-date and accurate framework data available. 

May 1, 2009 303-104
Virginia Geospatial Extension Program -- GPS Utility: A User Guide for Natural Resource Professionals and Educators

GPS Utility is an easy-to-use software application that allows you to manage, manipulate, and map your GPS information. This is a “point-and-click” software package that is fairly user-friendly

May 1, 2009 303-202
Virginia Geospatial Extension Program -- Navigator: A User Guide for Natural Resource Professionals May 1, 2009 303-201
Virginia Geospatial Extension Program -- The Garmin eTrex Legend: An Introductory Handbook for Natural Resource Professionals and Educators May 1, 2009 303-204
Virginia Geospatial Extension Program -- USA PhotoMaps: a User Guide for Natural Resource Professionals and Educators Nov 5, 2009 303-203
Web-based Vineyard Site Evaluation Tool Mar 27, 2013 ANR-62NP