Detlef Ehlert

Learn More
Knowledge of site-specific crop parameters such as plant height, coverage and biomass density is important for optimising crop management and harvesting processes. Sensors for measuring crop parameters are essential pre-requisites to gather this information. In recent years, laser rangefinder sensors have been adopted in many industrial applications. In(More)
A sensor for measuring crop biomass density has been designed and developed to meet the demands for practical use in site-specific farming. The mechanical sensor named ‘Crop-meter’ is based on the pendulum principle. The suitability and measuring stability of the Crop-meter has been confirmed under field conditions in different regions of Germany.(More)
Site-specific nitrogen fertilisation is important in precision agriculture. Based on positive results from a mechanical sensor (pendulum-meter) for the indirect measurement of existing plant mass in cereals, late nitrogen fertilisation in a farm scale strip trial was tested in the growing seasons of the year 2000 in one field and 2001 in two fields. The(More)
In recent years, laser rangefinder sensors have been introduced to the practice and research of agricultural engineering. In research, laser rangefinders have been investigated in horticulture and agriculture. For vehicle-based determination of crop biomass, commercially available laser rangefinders have been analysed and tested to measure aboveground(More)
Real-time technology was developed and tested to variably apply fungicides on the plant surface of cereals. An important step towards variable-rate fungicide application in real time is the development and operation of online sensors for measuring plant parameters. The sensor signal of the CROP-Meter (real-time sensor to measure crop biomass density) is(More)
A vehicle-based mechanical sensor (pendulum-meter) was developed to measure the plant mass of crops. For testing under defined conditions, a dynamometer with pendulum-meter, sensory and electronic equipment was developed. The ability and accuracy of the sensor for measuring plant mass in different crops (winter wheat, winter rye, grass, rice) and different(More)
The objective of this study was to evaluate the distribution of soil strength (measured as cone index, CI) along a 600 m transect and to determine the soil loosening depth necessary to eliminate zones with soil strengths exceeding a threshold value down to a depth of 0.6 m. The transect was located at a site in a glacial drift area which was characterised(More)
Nitrogen (N) fertilization implies two important issues: N enhances grain yields and quality, but applied in excess, nitrous oxide emissions and nitrate leaching may be induced. To reduce environmental impacts, spatial N variability in agricultural fields can be adapted using crop sensors. In on-farm experiments, sensor-based variable rate N application is(More)