Cultivation Practices and Potato Cultivars Suitable for Organic Potato Production

To identify the most important agronomic measures and cultivar traits in Swedish organic potato production, multivariate analyses were performed on a set of data from a series of field trials carried out in Sweden during a 7-year period. The effects of soil parameters, cultivar, year and geographical location on potato characteristics were investigated. Soil parameters including fertility level had strong and significant effects on potato characteristics, explaining 53% of total variation. Variables related to the duration of haulm growth were other dominant factors in the variation. While P and K fertilization increased yields, N fertilization had little effect on yield and a negative effect on the time to emergence. The N requirement of potatoes ranges from 2.5 to 5.9 kg ha^?1 per ton of tuber yield and was met in these trials. The results implied the timing of N application is important for yield. It was concluded that the importance of P and K fertilization is underestimated in organic production, and that the most important cultivar trait in achieving acceptable yield is long-lasting foliage, which is a characteristic of cultivars resistant to Phytophthora infestans. Three of the cultivars tested (Lady Balfour, Cicero and Sarpo Mira) had a yield >3.5 kg m^?2, which is high in Swedish organic production.