GRAIN MOISTURE METER SPAD 502 Plus Chlorophyll Meter The SPAD 502 Plus Chlorophyll Meter instantly measures chlorophyll content or “greenness” of your plants to reduce the risk of yield-limiting deficiencies or costly overfertilizing. The SPAD 502 Plus quantifies subtle changes or trends in plant health long before they’re visible to the human eye. Non-invasive measurement; simply clamp the meter over leafy tissue, and receive an indexed chlorophyll content reading (-9.9 to 199.9) in less than 2 seconds. Assess nitrogen needs by comparing in-field SPAD readings to university guidelines or to adequately fertilized reference strips. Research shows a strong correlation between SPAD measurements and leaf N content. Instantly measures chlorophyll content or “greenness” of your plants on a scale of -9.9 to 199.9 Non-invasive, non-destructive measurement Trend graph stores and displays up to 30 measurements Waterproof design Compare in-field SPAD readings to university guidelines Research shows a strong correlation between SPAD measurements and leaf N content Available with or without a built-in data logger Includes hard carrying case and batteries Data-logging model (2900PDL) Connects to any GPS receiver that has a serial output option* Equipped with internal data logger and RS-232 port Records 4,096 measurements (1,488 with added GPS/DGPS option) Configure and download meter with FieldScout® software (included)** Compatible with SpecMaps™ online web-mapping application Optical Density Difference at two wavelengths: 650 nm and 940 nm Measurement Area: 2 mm x 3 mm  (Approximately 3/32 in x 1/8 in) Light Source: 2 LEDs Receptor: Silicon Photodiode Power Source: 2 AA alkaline  batteries (1.5V) Repeatability: Within ±0.3 SPAD unit SPAD Value: Index of relative chlorophyll content; -9.9 to 199.9