GPS and Precision Ag Technologies Is There Anything New? Kent Shannon Associate Director Missouri Precision Agriculture Center

GPS and Precision Ag Technologies Is There Anything New? GPS – Handheld (Low-Cost) Handheld Computers / Software GPS Guidance – Lightbars / Automatic Yield Monitors Sensors

Comparison of Various Recreational GPS Receivers 12 different recreational GPS receivers and a common DGPS receiver used for precision ag applications Compared to a Ashtech Z-Surveyor RTK GPS receiver with a 3-10 cm horizontal accuracy

Equipment Used for Data Collection Recreational GPS Receivers Used –Garmin – 7 models –Magellan – 2 models –Lowrance – 1 model –Teletype Compact Flash - WAAS –Navman – iPAQ sleeve - WAAS –Starlink Invicta 210 – DGPS receiver – Coast Guard Beacon

Equipment Used for Data Collection Garmin – 7 models –eTrex –Geko WAAS –eTrex Legend - WAAS –eTrex Vista - WAAS –GPS 76 - WAAS –Rino WAAS –GPS III Plus

Equipment Used for Data Collection Magellan – 2 models –Meridian GPS - WAAS –SporTrak Map - WAAS Lowrance iFinder - WAAS

Equipment Used for Data Collection Used PocketPC computers running VisualGPSce to collect raw NMEA data GPS receivers antennas mounted 1.88 m (74 in) apart from each other

Location for Data Collection 610 m 205 m RTK Base Station

Testing Pattern

Testing Pattern – Data Used for Analysis

Methodology for Data Collection Tests consisted of four time periods, each on a different day. –Two days of testing were conducted at 19.1 km/hr (11.9 mph) for 12 minutes –Two days of testing were conducted at 13.2 km/hr (8.2 mph) for 16 minutes Each time period receivers were tested using a Randomized Complete Block Design

Results and Discussion Relative Accuracy –95 th percentile value –Mean –Standard Deviation Ability to acquire WAAS correction and effect on relative accuracy

Note: Distance of 1.88 meters between GPS antennas taken into account LSD (0.05) = 2.34

Note: Distance of 1.88 meters between GPS antennas taken into account

LSD (0.05) = 1.21 Note: Distance of 1.88 meters between GPS antennas taken into account

Ability to Acquire WAAS Differential Correction

LSD (0.05) = 1.21 Note: Distance of 1.88 meters between GPS antennas taken into account

Conclusions Recreational GPS receivers perform well if WAAS differential correction is acquired in a straight line trajectory. There is some differences between recreational GPS receivers. Further work needs to be done, i.e. contours and using external antennas.

Yield Data Collection with “Low-Cost” GPS Receivers GPS76 with a GA27C External Antenna PC/Cigarette Lighter Combination Cable Holux GM-210 with Serial Connection and Cigarette Lighter Adapter

Corn Yield Map Made With Holux GM-210 GPS and Garmin GPS76 GPS

Palm OSPocket PC Handheld Computers Palm/Handspring –Zire, Tungsten, Treo Smartphones Sony –CLIÉ Compaq/HP - iPAQ 2215 Dell Axim X5 Toshiba – e750 ASUS – A620 ViewSonic – PCV37 Zayo – A600

Farm TracMate SST Stratus MapShots Pocket Crops Using Non-GPS Crop Recordkeeping Software on a PocketPC

Adding GPS for Crop Recordkeeping Integration of FarmWorks – TracMate and SiteMate

Adding GPS for Crop Recordkeeping SST Stratus and Summit

GPS Aided Guidance Lightbars

GPS Guidance Automatic

Yield Monitors and Controllers CAN Bus

Aerial Photograph from June 20, 2003 used for Development of Sidedress Nitrogen Application and Zones Developed

Greenness Ratio = Greenness of Nitrogen Sufficient Plots Greenness of Nitrogen Deficient Plots Nitrogen Rate = ( (Greenness Ratio)) x 0.89 Formula based on research by Scharf and Lory, Calibrating Corn Color from Aerial Photographs to Predict Sidedress Nitrogen Need Agron. J. 94: (2002)

Research Data from Scharf Used to Calculate EONR From Chlorophyll Meter from June 19, 2003 In Zone 4, in-field information from a SPAD meter was used to calculate a side-dress amount of nitrogen of 150 lbs/acre

LSD (0.05) = LSD (0.05) = LSD (0.05) = 7.76 LSD (0.05) = 8.00 LSD (0.05) = 4.60

Economics of the Nitrogen Management Strategies Used $0.28/lb for Nitrogen and $2.40/bu for Corn

Where are we going from here? Using the relationship of the amount of biomass to nitrogen need

Any Questions?