The difference in the effects of six crop rotations, grass-clover ley, Miscanthus, and bare fallow on the amount of drainage runoff, nitrate concentration, and the amount of nitrate leached to groundwater was investigated during seven years (1993-1999) using lysimeters (1 m2 surface and 1.4 m usable depth, filled in 1982 with a low humus, loamy sand). The results revealed differences depending on precipitation, rotation, and degree of vegetation cover. Seven-year average nitrate losses of rotations involving cover crops were 85 kg N/ha and thus one third lower than those of rotations without cover crops. Averaged over all six rotations and bare fallow, nitrate concentration during the whole year exceeded the tolerance level for drinking water of 40 mg NO3/l. Different types of pre-cultivation can lead to different nitrate losses during the main cropping period. Thus, with respect to nitrate leaching, the sequence of crops should receive more attention.
Symbiotic nitrogen fixation by bacteria in the soil coexisting with legumes leads to reduced fertiliser requirement. It is not easy to measure this variable on farms, however. Now researchers from Agroscope have developed a method for estimating nitrogen input via symbiotic fixation at farm level.
With increasing global and regional temperatures, even in Switzerland the growing season has lengthened considerably. Using data from the Federal Office of Meteorology and Climatology, Agroscope has traced the development of the growing season since the start of the previous century.
The phosphate mineral reserves required for fertiliser production could be exhausted on a global scale in just a few decades. This study presents a method for recycling a Swiss industrial by-product into a phosphate fertiliser.