Impact of Crop Sequence and Fertilization on Potato Yield in a Long-Term Study.

The research was conducted during the years 2007-2013, on the base of a long-term study established in 1958, at the Experimental Station Brody (52°26' N; 16°18' E), belonging to the Poznań University of Life Sciences. Varieties of potatoes resistant to cyst nematodes were grown in a seven-course crop rotation (potato-spring barley-alfalfa-alfalfa-spring oilseed rape-winter wheat-winter rye) and in continuous monoculture. The presented study from the years 2007-2013 covers the next 8th rotation of the 7-field crop rotation (since 1958). With regard to continuous cultivation, this is the period between the 50th and 56th year of the potato monoculture. The experiment included 11 fertilization variants, of which the following 7 were included in the study: 1-control object without fertilization, 2-manure, 3-manure + NPK, 4-NPKCa, 5-NPK, 6-NP, 7-NK and 8-PK. Every year, mineral and organic fertilization was applied in the following doses per 1 ha: N-90 kg, P-26 kg, K-100 kg, manure-30 t and Ca-0.7 t. Potato cultivation in monoculture resulted in a significant reduction in tuber yield compared to crop rotation and a reduction in the number of tubers per plant and the average weight of one tuber. Manure fertilization, especially in combination with NPK mineral fertilizer, had a more favorable effect on the level of potato yielding and the content of N, P, K and Mg in tubers compared to only mineral fertilization, but decreased the content of dry matter, starch and Ca. The results of long-term experiment indicate that the most effective in potato cultivation is the combined application of both manure and full mineral fertilization (NPK) with the proper sequence of plants (crop rotation).