Summary:

Field experiment was carried out in the years 2003–2006 in ES in Lipnik near stargard (Szczecin region) on sandy soil belong to god-rye-complex. The experiment was set up by split-plot method in seven repetitions. Between the trees there was sward and in the rows the herbicidal farrows there kept. The aim of the studies was to determine the effect of under crown irrigation and mineral fer-tilization on the yield of plums cv. ‘Amersis’ and ‘Cacańska Rana’. The first fac-tor of the study was supplemental irrigation (0-control without irrigation: W- under crown irrigation). The second factor was different level of mineral fertiliz-ing: 0NPK, 1NPK – 130kg . NPK. ha^-1 (40+30+60), 2NPK - 260kg . NPK. ha^-1 (80+60+120). Supplemental irrigation was used when the tensiometer have shown that water potential of soil dropped lower than 0,01 MPa. For irrigation the ‘Hadar’ sprinkler were used (r=2m). Depending on rainfall the amount of ir-rigation from 21,0 to 37,9 mm there used. As effect of irrigation the yields in-creased by 19,2%. The highest increased (36,1%) was obtained in 2006 and the lowest (8,2%) in 2005. To evaluation the effects of mineral fertilizers the highest crops obtained from the plots fertilized with 2NPK (260kg . NPK. ha^-1). Increase of crops comparing to control (without fertilizers) respectively equal 48,3 and 39,9%. Gross and net productivity of 1 mm used water depended on weather, conditions in the years. The highest productivity factors net (209,5 kg.1mm.1ha^-1) and gross (74,14 kg.1mm.1ha^-1) was obtained in 2004 year. Net productivity of 1 kg NPK depended on the level of fertilizing and was the highest when 130kg . NPK. ha^-1 was applied.