SENSOR BASED FINE TUNING OF NITROGEN FERTILIZER APPLICATIONS USING SPECTRAL FEEDBACK SIGNALS FROM TOMATO PLANTS (LYCOPERSICON ESCULENTUM MILL.)
The advantages of precision agriculture in vegetable growing and the high value crop sector may accrue to horticulturists, especially with respect to meeting quality standards and in carrying out selective and subsequent harvest. However, the implementation and use of site-specific sensor technologies has not yet been adopted for horticultural purposes sufficiently in the context of nitrogen (N) fertilization. Suitable sensor technologies and especially crop specific calibrations to determine crop N status and to adapt N fertilization strategies are still missing. The aim of this study was to evaluate the use of a passive sensor technology and, thus, spectral feedback signals from tomato plants to determine the N status, and to adapt N fertilization rates throughout the cultivation period. A greenhouse study was conducted with tomato plants over three months (April-June). Three different N fertilization rates (30 kg ha-1, 60 kg ha-1, and 100 kg ha-1) were implemented. As soon as the first inflorescence of the tomato plant was visible, sensor measurements were carried out on the first expanded leaf above the inflorescence with a digital imager (Leica S1 Pro) and repeated once a week. Reflectance of tomato plants increased under sufficient N supply but decreased under N deficiency, which enabled the discrimination of N status of tomato plants and, thus, the adaptation of N fertilization rates. The results of the study indicated that the fine tuning of fertilizer operations using feedback signals from tomato plants based on sensor measurements may be a promising way for optimizing N fertilizer inputs in horticulture and, thus, also, for enhancing crop yield and quality.
Pfenning, J., Liebig, H.-P., Graeff, S. and Claupein, W. (2009). SENSOR BASED FINE TUNING OF NITROGEN FERTILIZER APPLICATIONS USING SPECTRAL FEEDBACK SIGNALS FROM TOMATO PLANTS (LYCOPERSICON ESCULENTUM MILL.). Acta Hortic. 824, 177-182
plant sensors, fertilizer recommendation, N