Sensors for Mapping Soil pH Eric Lund, Veris Technologies, Salina, KS Sensors for Crop Management Conference Stillwater OK January 17, 2008

How does it work? How accurate is on-the-go pH mapping? Does managing pH pay? On-the-go pH mapping

On-the-go pH mapping is here...

HERE’S HOW IT WORKS: A sampler shank is lowered into the soil A soil core flows through the sampler trough The soil core is raised against two pH electrodes The geo-referenced pH and EC data are recorded The entire process is automated Automated pH Mapping How Does It Work?

How accurate is on-the-go pH mapping from Veris Technologies? Statistical analysis Visual comparisons Repeatability

Statistical analysis Field Trials: 328 validation samples...15 fields...4 states...

Statistical analysis

Visual comparisons Lab samples overlaid on Veris pH sensor data

Visual comparisons Lab samples overlaid on Veris pH sensor data

Visual comparisons

Repeatability

Significantly more accurate liming than other methods. How do the results compare? 2.5 acre grids, zones, blanket rate

Does managing pH pay?

University of Nebraska study Lime vs. no lime Corn-bean rotation 7 yr study (but data still being collected) Corn $2/bu Soybeans $5.50/bu

Soil EC zones

Take-home messages pH varies widely within most fields On-the-go pH sensing can accurately map pH variability Soil EC zones are another alternative—not as precise as on-the-go sensing, but typically better than blanket rate Lime economics vary by field, but: -low pH levels in OK fields call for lime -since many fields have areas that need zero or a reduced lime amount, precision lime should pay