The Study of Applicability to Fixed-field Sensor for Normalized Difference Vegetation Index (NDVI) Monitoring in Cultivation Area

Abstract

The NDVI (Normalized difference vegetation index) is used as indicators of crop growth situation in remote sensing. To measure or validate the NDVI, reliable NDVI sensors have been needed. We tested new fixed-field NDVI sensor, "SRS (Spectral Reflectance Sensor)" developed by Decagon Devices, during Kimchi cabbage growing season at the cultivation area located in Gochang, Gangneung and Taebaek in Korea from 2014 to 2015. The diurnal variation of NDVI measured by SRS (SRS NDVI) showed a slight ∩-profile shape and was affected by water on the sensor surface. This means that SRS NDVI around noontime is resonable, except rainy day. Comparisons were made between the SRS NDVI and NDVI of used widely mobile sensor (Cropcircle NDVI). The comparisons indicate that SRS NDVI are close to Cropcircle NDVI (R=0.99). SRS NDVI time series displayed change of the plant height and leaf width of Kimchi cabbage. An obvious exponential relationship is found between SRS NDVI and the plant height (R 2 ≥0.92) and leaf width (R 2 ≥0.92) of Kimchi cabbage. Thus, SRS NDVI will be used as indicator of crop growth situation and a very powerful tool for evaluation of remote sensing NDVI estimates and associated corrections.Key words: NDVI, SRS sensor Relationship between NDVI measured by SRS and NDVI measured by Cropcircle.

Development of an Apparatus for Crop-Growth Monitoring and Diagnosis

“…The Finnish Geospatial Research Institute (Helsinki, Finland) designed a two-band laser radar powered by a supercontinuum source, working at wavebands of 600 nm and 800 nm, to distinguish vegetation and inorganic materials by constructing the NDVI [ 14 ]. Decagon Devices (Pullman, WA, USA) have developed a portable SRS radiometer, operating at two wavebands (630 nm and 800 nm), which calculates NDVI by measuring canopy radiation intensity [ 15 ]. By using the two-band spectrometer–Greenseeker produced by Trimble Navigation (Sunnyvale, CA, USA) in the United States, the normalised vegetation index (NDVI) is constructed through measuring canopy reflectance of crops [ 16 , 17 , 18 ].…”