Jörn Selbeck

On-the-go Phenotyping in Field Potatoes Using Camera Vision

A camera sensor for detecting crop parameters, with the aim of implementing precision plant protection, has been developed at the Leibniz Institute for Agricultural Engineering. This sensor was tested in farmers’ potato fields regarding the phenotyping and monitoring of crop growth. Field trials were conducted in 2007, 2011 and 2012 to quantify the relationship between the sensor measurements of the coverage level by the green stem and leaf parts and two plant parameters: the fresh mass of the tops and the leaf area index. Within the fields, sampling points were chosen based on differences in crop development. At different dates, the sensor values (coverage level) and the two plant parameters were determined. Because of the shape of the obtained scatterplots between the two plant parameters and the coverage level, a linear regression model with a plateau was adapted. An on-the-go (on-line, real-time) technology for measuring the percentage of green coverage was tested to monitor the development of the potato crop during the growth period. The sensor was positioned on the left side of the tractor to scan the crop stand along transects. The coverage level was measured and recorded together with the geographical position using a data processing system. Areas showing different plant growth could be determined, as could differences in the temporal development of the crop in the various sections of the transect.

Terahertz Spectroscopy for Proximal Soil Sensing: An Approach to Particle Size Analysis

Spatially resolved soil parameters are some of the most important pieces of information for precision agriculture. These parameters, especially the particle size distribution (texture), are costly to measure by conventional laboratory methods, and thus, in situ assessment has become the focus of a new discipline called proximal soil sensing. Terahertz (THz) radiation is a promising method for nondestructive in situ measurements. The THz frequency range from 258 gigahertz (GHz) to 350 GHz provides a good compromise between soil penetration and the interaction of the electromagnetic waves with soil compounds. In particular, soil physical parameters influence THz measurements. This paper presents investigations of the spectral transmission signals from samples of different particle size fractions relevant for soil characterization. The sample thickness ranged from 5 to 17 mm. The transmission of THz waves was affected by the main mineral particle fractions, sand, silt and clay. The resulting signal changes systematically according to particle sizes larger than half the wavelength. It can be concluded that THz spectroscopic measurements provide information about soil texture and penetrate samples with thicknesses in the cm range.

Vegetationserkennung für landwirtschaftliche Anwendungen mithilfe einer Ein-Chip-Kamera

Durch die Anwendung von Kameras bei der Prozesskontrolle in der Prazisionslandwirtschaft konnen Dunger, Pestizide, Maschinenzeit und Treibstoff eingespart werden. Trotz der hohen Forschungsaktivitaten auf diesem Gebiet verhindern hohe Preise fur geeignete Kamerasysteme die Anwendung in allen Bereichen der Landwirtschaft. Intelligente und kostengunstige Kameras, die fur landwirtschaftliche Anwendungen angepasst werden, konnen diesen Nachteil uberwinden. Der normalisierte differenzierte Vegetationsindex (NDVI) ist ein Algorithmus in der Bildanalyse zur Trennung von Pflanze und Boden (Hintergrund) und wird in der hier vorgestellten Untersuchung bei einer kostengunstigen Ein-Chip-Kamera implementiert und angepasst.

Methoden für die präzise obstbauliche Produktion

Der Ansatz von Precision Horticulture im Obstbau lehnt sich an das aus dem Ackerbau stammende Konzept der Prazisionslandwirtschaft bzw. der teilflachenspezifischen Bewirtschaftung an. Hierbei sollen prazise an das individuelle Geholzwachstum angepasste Pflegemasnahmen die bislang praktizierte einheitliche Behandlung aller Baume in einer Anlage ablosen. Voraussetzungen hierfur sind u. a. Bodenkarten und Informationen zum Pflanzenwachstum. Das Ziel ist es, den informationsgestutzten Obstbau voranzutreiben und durch ein raumlich und zeitlich differenziertes Management eine effizientere und nachhaltigere Bewirtschaftung zu erreichen.