Nitrogen fertilization trials were conducted in Switzerland with potato cultivars Lady Felicia, Derby, Victoria, Innovator and Marlen in Changins (VD) and Reckenholz (ZH). N Mineral fertilizer treatments varied from 0 to 200 kg N/ha, applied in one to three dressings from plantation until complete soil covering by the plants. The cultivars tested responded similarly to the nitrogen supply. Yield of the tested varieties didn’t significantly increase by nitrogen application higher than 80 kg N/ha in Reckenholz and 160 kg/ha in Changins. This gap can be explained by the difference in mineral nitrogen status of soils at plantation; N mineral content is generally higher in Reckenholz at the beginning of the growing season. Focusing on tuber size of cultivar Derby, the yield of commercial tubers (size 42,5 – 70 mm) did not appear significantly increasing with N fertilization higher than 80 kg N/ha in Changins. Derby seems to have good N use efficiency. Generally, nitrogen improved the yield in commercial tubers and over-sized tubers. Nitrogen has little impact on starch tuber content. Indeed, only small variations of starch content could be observed with increased N supply. Nitrogen had limited impact too on tuber quality of the varieties dedicated to crisps production. As a conclusion, nitrogen supply has to be adapted to cultivars but also to soil mineral nitrogen status at planting time.
Nitrogen supply of new potato varieties cultivated in Switzerland