Summary:

The field experiment was conducted in the years 2006–2008 at Plant Breeding and Acclimatization Institute, Division Jadwisin on the light and acid soil. The aim of the research was to compare tubers yield, their structure and some quality elements of tubers (content of nitrates and starch, percentage of de-formations, green tubers, common scab infection) different fertilization doses of solid and liquid nitrogen form (fertigation) applied to the soil. The objects were divided on: irrigated and non irrigated. Drip irrigation method was applied in this experiment. The nitrogen dose in fertigation form was established by using com-puter program DSS (Decision Support System). The nitrogen in fertigation form was applied in following doses: year of 2006 – 57,7 kg•ha^-1, year of 2007 – 31,7 kg•ha^-1, year of 2008 – 39,7 kg•ha^-1. The doses of water (year of 2006 – 110,3 mm, year of 2007 – 20,0 mm, year of 2008 – 68,9 mm) and dates of their application were established by using tensjometer. The control was object without fertiliza-tion of NPK and without irrigation. The significant highest yield of tubers was obtained on the irrigated object where dose of 150 kg•ha^-1N was applied. The yield of tubers on irrigated object by using fertilizer program DSS was about 47,3% higher than on the control object. On the irrigated objects the increase of big tubers share in the yield (diameter above 60 mm), decrease of nitrates content in tubers and smaller share of tubers with deformations less common scab infec-tion than on non irrigated were observed.