An assessment of crop water deficits of the plants growing on the Małopolska Upland (Poland)

The problem of water scarcity is unfavourable for the economy, with the most significant water deficits felt by agriculture. In Poland water deficits in agriculture are occurring more frequently, causing losses in yield, not only in the Lowland areas but also in the Uplands. This paper presents an assessment of the water deficits at various excedance probability levels for four varieties of field crop and for soil types with various water retention capacity, which occur in the Małopolska Upland. Calculations were performed by balancing the amount of available soil water in the root zone. The study was based on the meteorological data from the Institute of Meteorology and Water Management for the years 1971–2010. Daily precipitation data from six rainfall stations: Borusowa, Igołomia, Książ Wielki, Miechów, Olewin and Sielec was utilised as well as average decadal air temperature, water vapour pressure, wind speed and sunshine hours from the meteorological station at Kraków–Balice. The water deficits at an excedance probability level of 20% fluctuated during the growing season from 5 mm (Phaeozems) to 190 mm (Leptosols). In the Małopolska Upland in soils with a medium capacity to retain water (110–160 mm), water deficits have occurred even in years of average rainfall (with probability 50%). This study confirms the considerable impact of the high variability of the soil and pluvial conditions in the region on the water deficits of the field crops.