In the DOK long-term field experiment two organic (D: biodynamic; O: bioorganic) and two conventional (K: mineral fertilizer plus farmyard manure; M: mineral fertilizer only) farming systems have been compared. In 1999, 2001 and 2002 dynamics of mineral nitrogen (Nmin) in plots planted with potato was analysed in the 0 to 100 cm soil layer. The preceding crop was always clover grass. In spring the plots were prepared by using a mouldboard plough followed by a rotary harrow. In the D, O, K and M treatments, a respective total of 25, 60, 110 and 110 kg plant available N/ha was applied. Mineralization and leaching of N was not consistent among years, which may be explained by differences in climatic conditions. Therefore, maximal Nmin contents in the 0 to 60 cm soil layer measured in May varied between 50 (1999) and 170 kg N/ha (2002). In June, when N uptake of potato usually is highest, Nmin contents in soils decreased in all cases to about 10 kg N/ha and afterwards continuously increased until senescence of the potato plants. Despite different N input, the dynamic of mineral N was similar in all treatments except for D and O in 1999, when an early infestation by potato late blight resulted in early senescence and thus in a reduced N uptake. After harvest Nmin contents tended to be higher for D, O, and K with organic fertilizers than for M with mineral fertilizer only. In conclusion, the risk for N leaching is highest after harvest of potato, which might be prevented by cultivation of a fast-growing cover crop immediately after harvest.
Those wishing to promote biodiversity in agriculture by means of result-based schemes need meaningful indicators. An overview of proposed and used indicators highlights developments and challenges.
Foods of animal origin – friend or foe? It all depends on the needs of consumers and on local production conditions, as shown by a major review in which Agroscope took part.
In vegetable production it is usual to leave crop residues on the field. Measurements carried out by Agroscope researchers show that removing these residues significantly reduces nitrate leaching.