Precision Farming Mapping EC with Veris Bobby Grisso Virginia Tech Biological Systems Engineering

Resources: Precision Farming - A Comprehensive Approach Precision Farming Tools: GPS Navigation Precision Farming Tools: Yield Monitor Precision Farming Tools: Global Positioning System-GPS Precision Farming Tools: Variable-Rate Application Precision Farming Tools: Soil Electrical Conductivity Investing in GPS Guidance Systems? Interpreting Yield Maps - "I gotta yield map - now what?“ Virginia Geospatial Extension Program

The Influence of Precision Agriculture !

Right source Right rate Right time Right place Precision Agriculture: Systems Approach

Precision Technology Use

Precision Agriculture Precise information on agronomic factors. Precise selection and placement of crop inputs. Precise position and travel information.

GPS Systems

Mapping EC with Veris 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.

EC MEASUREMENT IN SOIL Electrical conductivity (EC) is the ability of a material to transmit (conduct) an electrical current and is commonly expressed in units of milliSiemens per meter (mS/m). Soil EC measurements may also be reported in units of deciSiemens per meter (dS/m), which is equal to the reading in mS/m divided by 100.

Example: (see circle) 15% sand 15% clay 70% silt The Textural Triangle

Cation Exchange Capacity Measured in hundredths of moles (cmol) of charge (cmol + ) per kilogram (kg) dry soil Units of expression are cmol + /Kg CEC’s usually range from <5 to around 30 cmol + for natural soils This is the same unit as meq/100 g, just gyrated around to fit the international system of units (SI). Many labs and books still report CEC as meq/100 g

Plant roots use cation exchange to assist in nutrient uptake from the soil— (a) Soil moisture surrounding the roots (b) Absorption of soil mineral nutrients by cation exchange

Absorption and leaching of soil nutrients in the soil solution

Cation exchange on soil particles — effects of soil pH

Electrical Conductivity is Highly Correlated with Organic Matter Moisture Content Soil Texture Compacted Zones Existing Soil Moisture Salts Good Nematode Correlation

EC Measure - Veris

Veris machine – note water tank

Sensor for Turf Management

Soils are 3-dimensional

3-D Landscape model 2-D Soil map

Mapping EC with Veris Soil EC maps often visually correspond to patterns on yield maps and can help explain yield variation

Yield Map – Why?

What does EC Look like?

Aerial Photo and Soil Map

Overlay the Soils Map

Mapping EC with Veris Other uses of soil EC maps, 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

Surface to Soil Map Boundaries

Subsurface to Soil Map Boundaries

Match with Aerial photos

Normalize data - Moisture

Tips for collecting soil EC data Take EC measurements when the soil is neither excessively moist nor very dry. Good soil-coulter contact is required for direct contact sensors. Best mapping conditions are found following harvest in smooth, untilled fields or prior to planting in prepared fields. In a corn-soybean rotation, conditions following soybean harvest may be most favorable since the soybean residue is less. Otherwise, firm but non-compacted soil and a smooth field surface are preferred for soil EC measurement. Avoid metal interferences with EM (non-contact) sensors by keeping a distance of about 4 to 5 feet between the sensor and any metal object. This can be accomplished with careful placement of the sensor beneath a high-clearance vehicle or on a custom- made cart constructed of nonmetallic materials. Conduct soil EC mapping when soils are not frozen. Collect data on measurement pass spacing no greater than about 60 feet. Experience shows that 40 to 60-foot passes provides a map that adequately identifies the spatial patterns of a field. Such a pass may represent half to a full spray-boom width or a multiple of the planter or combine width, and consequently the smallest area most growers will variably manage. To add value to your soil EC maps, it is important to take a deep soil sample or compaction measurement at a few points in each field. Soil physical characteristics and moisture measurements will aid in interpreting what is causing soil EC variations. The sampling should be done at the same time as soil EC data are collected.

Good soil-coulter contact

Stay out of the mud

Uses of EC Maps

Precision Agriculture: Systems Approach

GPS Global Positioning System Characteristics Free Accurate Reliable Worldwide Unlimited user capacity 60’s TRANSIT – doppler system ’95 Fully Operational Condition (FOC)

SOME GPS APPLICATIONS  MILITARY  MARITIME  AUTOMOTIVE  SURVEYING  AVIATION  AGRICULTURE  FORESTRY  ENVIRONMENTAL  PUBLIC SAFETY  HIKING  HUNTING  NATURE STUDY  FISHING  BOATING  BIKING  SKIING  SNOWMOBILING  GEOCACHING  GOLF ! COMMERCE & GOVERNMENT RECREATIONAL

Space Segment 28 Rockwell satellites 7.5 yr life span 6 orbital 55 degree orbits 2 orbits everyday Very high orbit (20,200 km) Radius of Earth ~ 8000 mi (~12,900 )

How GPS works… Satellite signals are broadcast at the speed of light (186,000 miles per second) Distance to satellite =11,200 miles 300,000 km/s a 1/1,000,000 sec Error =>300 m pos. Error

GPS current issues

Section Control Systems

All machinery must pay…

Precision Ag Services Offered

Who’s Leading the Green Index ?

Ag Journey

Innovation

Automated Guidance Implement Guidance Variable Rate Overlap Switching Data Transfer 12.0% 3.0% 7.3% 4.6% ? 12.0% Total Savings Value Proposition 15.0%22.3%26.9% >26.9% Engineers working on Automatic Guidance and Precision Agriculture have increased productivity by 27% in the last 14 years

GPS Options for Turf GPS m Autonomous m S/A DGPS.5 - 5m RTK Float 20cm RTK Fixed 1cm

DGPS Accuracy – Trimble Units

Sprayer Navigation

GPS Navigation Aids:

Reliable and more accurate Accuracy at higher speeds Easily used with spinner spreaders Easy to use – less skilled operator Effective over growing crops Allows operation when visibility is poor Less affected by weather Lower recurring costs Reduces operator fatigue and eye strain Lower set-up time Not effected by wind or boom bounce Reduces overlaps and skips Reduces need for people in sprayed areas

GPS Navigation Aids:

GPS Navigation Systems: Boomless Sprayers Spreaders

New VCE Publications Investing in GPS Guidance Systems? Precision Farming Tools: GPS Navigation Check with local county agent for details

Self-Steering RTK

Autonomous Vehicles:

Scouting Tools

Remote Controlled Aircraft Spraying and Video Scouting:

Aerial Photograph

Combines: Yield Monitors

Sensor for Turf Management

Soil Sampling Methods

Soil Sampling

Application Decisions?

Closed systems

Boom Height Control Operator Comfort Drift Control Proper Spray Tip Height For Better Chemical Distribution Protect Boom Ends

Air-assisted sprayers

Smart Sprayers Computer guided Vision systems on sprayers Real-time ID weeds, insects, diseases Determine where, what, and when to spray

Greenseeker – N rate control

Ten Agricultural and Biological Engineering Achievements that Changed the World

10 Engineering Achievements 1.Development of the Agricultural Tractor 2.Rural Electrification 3.Self-Propelled Combine 4.Center Pivot for Irrigation 5.International Harvester Cotton Picker 6.Milking Machine 7.Conservation Tillage 8.ASABE Standardization Procedure 9.Rubber Tires on Tractors 10.Refrigerated On-Farm Milk Storage

Precision Agriculture: Systems Approach