The yield and other quantitative (number of plants, number of tubers, weight of tubers per 1 m2) and qualitative parameters (content of vitamin C, starch, nitrogen and dry matter) of the Solanum tuberosum L. early variety “Collete” have been studied in ecological and low-input farming systems with two levels of organic fertilization during 2003-2005. The experiment was situated in water-protected zone of western Slovakia on Luvi-Haplic Chernozem. After harvest of forecrop in higher level of organic fertilization treatment catch crop – phacelia and mustard was grown. Highly significant differences in each studied parameters of potato tubers between certain years were ascertained, thus great influence of weather conditions on quality and quantity of potatoes was confirmed. Yields was highly significantly influenced also by farming systems, when in low-input system the average yield was 21.38 t ha-1 and in ecological system 20.02 t ha-1. Green manure management did not influence
yield significantly. In treatment without green manure the average yield 20.47 t ha-1 was reached with comparison to green manure application treatments 20.93 t ha-1. In low-input system significantly higher C vitamin content (4.23 mg 100g-1) was ascertained compared to ecological one 3.53 mg 100g-1. Other qualitative parameters were more or less on the same level. We recommended both farming system for growing potatoes in water vulnerable zones and for better fulfil the Good Agricultural Practices in Slovak conditions.
