EVALUATION OF DIFFERENT ACTIVE AND PASSIVE SENSOR SYSTEMS TO ADAPT N FERTILIZER APPLICATIONS IN BROCCOLI (BRASSICA OLERACEA CONVAR. BOTRYTIS VAR. ITALICA)
Horticultural cropping systems are well suited to site-specific sensor techniques and information management systems. Technological developments in electronics and sensors in precision farming create the possibilities for a more precise production system that takes into account the natural variability of biological production and its environmental influences. The aim of this study was to test different active and passive sensor technologies to monitor nitrogen (N) status in broccoli leaves and to derive suitable N fertilization strategies based on sensor measurements. A field study was conducted with two different common broccoli cultivars Parthenon and Marathon and six different N fertilization treatments consisting of 0, 76, 152, 200, 248, and 304 kg N ha-1. Space timing of N application was set to the start of cultivation at setting and after a four week growing period. Sensor measurements started three weeks after setting and were carried out once a week until final harvest of broccoli heads. Sensor technologies used included the passive sensors SPAD-Meter (Minolta), N-Tester (Yara), digital imager (Leica) and one active sensor. The investigation of the spectra from 380 to 1300 nm indicated that wavelength bands around 500-600 nm seem to be well suited for the identification of N status in broccoli plants. Further, the results indi¬cated that sensor technologies make it possible to monitor and control the N demand in broccoli plants and to adapt N fertilizer requirements during the growing season. By detailing this data to small areas within a field, through the application of spatial data, the data can be transformed into powerful management tools. This will enable growers to target their production and fertilizer input to soil variability, to market and quality related issues, and to deliver broccoli with optimal quality attributes.
Graeff, S., Claupein, W., Pfenning, J. and Liebig, H.-P. (2009). EVALUATION OF DIFFERENT ACTIVE AND PASSIVE SENSOR SYSTEMS TO ADAPT N FERTILIZER APPLICATIONS IN BROCCOLI (BRASSICA OLERACEA CONVAR. BOTRYTIS VAR. ITALICA). Acta Hortic. 824, 133-140
plant sensors, nitrogen, fertilizer recommendation