Site-specific fertilisation with regards to spatial and temporal nitrogen variability

Field tests on a farm in Saxony have been conducted in the last few years focusing on the spatial distribution of mineralised nitrogen in the soil and site-specific fertilisation. A sequence of the nitrogen distribution was recorded. The median obtained in the spring testing was about 40 kg/ ha nitrogen in a depth of 0 to 90 cm, but with different quartile distances. The site-specific fertilisation was based on different methods: without fertilisation, a nitrogen model and an on-line sensor for crop nitrogen status. The range of the given nitrogen was between 75 and 195 kg/ha. The repeatability of the on-line nitrogen sensor results was investigated. The sensor showed good results. Also a comparison of different methods to detect the nitrogen content in the plant has been made. The methods were the sensor mentioned above and a hand-held so-called Hydro-N-Tester. With this Hydro-N-Tester it is possible to detect the nitrogen status of a plant off-line. The results obtained with these two methods were quite comparable.