The aim of the present study was an attempt to calculate the cost-effectiveness of asparagus postharvest drip irrigation in the Central Poland. The results of field experiments on drip irrigation of 13 North-American asparagus cultivars, carried out at Kruszyn Krajenski in the vicinity of Bydgoszcz were investigated in the zone of the largest precipitation deficiency in Poland. The drip irrigation system's economic calculation was conducted following the methodology suggested by Grabarczyk (1987). The effectiveness of drip irrigation (ranging from 0 to 157 %) was the highest for cultivars Jersey Deluxe (157 %) and Jersey Giant (142 %). Lack of significant response to drip irrigation was found in case of cultivars Purple Passion, Jersey King and Atlas. Other cultivars (Jersey Supreme, Jersey Knight, Grande, Apollo, UC 157, NJ 953, UC 115, JWC 1) gave an increase in marketable yield of 35-79 % due to drip irrigation. Economic results of drip irrigation, depending on the increase in produce value and assumed drip irrigation costs were positive in case of 10 cultivars. The drip irrigation of Jersey Deluxe and Jersey Giant turned out most cost-effective. Irrigation was also very costeffective in the case of cultivars UC115, NJ953, Jersey Knight, Jersey Supreme, UC157, Grande, Apollo and JWC 1. Drip irrigation was unprofitable in case of the following cultivars: Purple Passion, Jersey King and Atlas.

The present paper concerns the results of long-term experiments on overhead irrigation of chosen medium early potato cultivars, carried out on a very light soil in the vicinity of Bydgoszcz (Central Poland). This region of Poland is recognized as the area of the lowest precipitation and the highest water deficits during the vegetation period. The investigation confirmed that the use of sprinkler irrigation under such soil-climatic conditions contributed to a very high multiyear productivity, which ranged from 43 to 191 %, depending on the cultivar. Increases in potato tuber yields caused by sprinkler irrigation were inversely proportional to rainfall during the vegetation period. The highest yield increases were obtained in dry years, whereas the lowest increases in the yields were noted in wet years. To estimate the economic efficiency of sprinkler irrigation the method of calculation of the increase in direct surplus was used. Economic results of sprinkler irrigation are dependent on the value of produce increase and assumed sprinkler irrigation costs. Total annual cost of sprinkler irrigation per 1 ha decreased with the increase of irrigated area. The highest values of the direct surplus were obtained for the cultivar Albina. The most profitable was sprinkler irrigation of potato in dry years.