In Poland, irrigation of plants cultivated in field has been not developed yet on a larger scale mainly due to unfavorable economic conditions and infrastructure. An increase of irrigated area is still prospective, and is a major standby of agricultural production. Factors accelerating the development of irrigation next to providing higher and stable yields of good quality are a need for competitiveness and modernity in farms as well as the projected climate changes. Main indicators of the purpose of irrigation are the effects of production; it means absolute increases in yields obtained under the influence of this treatment in agricultural production technology. Quantity and value of the effects of irrigation production can be analyzed in terms of the average (mean years) or in relation to a particular growing season. In the first case, the effects depend primarily on the criterion of the soil, and the secondly – on the meteorological conditions, particularly the amount and distribution of rainfall. The cognitive aim of this study was finding a significant correlation between the amounts of the production effects under irrigation and selected indicators of meteorological and agricultural drought during periods of increased water needs for tested plants. The utility goal was to propose a forecast method of application of these results based on a temporal and spatial variability of these indicators. The research was accomplished on the basis of long-term, field experiments with irrigation of following crops: table potatoes, malting barley, beans and corn harvested for grain. The experiments were conducted in the years 2006-2012 at the Research Station of University of Technology and Life Sciences in Mochełek, located nearby Bydgoszcz on Luvisols, grouped to the class IVa and very good rye complex of valuation on agricultural suitability. The tested crops were optimally irrigated in periods of agricultural droughts, and were guaranteed by moisture content in a layer of soil with a controlled water supply readily available to plants over the whole period of increased water needs. In the seven-year research period the production effects of irrigation for the certain crops were characterized by very high temporal variability. For example, for malting barley the effects amounted to an average of 1.44 t.ha-1, varying from 0 (in the year 2009) to 3.39 t.ha-1. These effects authors subordinate to selected indicators of meteorological and agricultural droughts during periods of increased water needs for the studied crops: rainfall (P), standardized precipitation index (SPI), the relative rate of precipitation (RPI), climatic water balance (KBW) and agricultural-climatic water balance (RKBW). In all cases, authors obtained significant relationships between the compared data which lead to a determination of variability of production effects with irrigation in the region of Bydgoszcz in different growing seasons (temporal variability), and allowed to predict the effects of irrigation plants in a distinct Polish rainfall zones (spatial variability). Compilation of the variability of production effects of irrigation in field crops is the basis for the analysis of the purpose of the treatment, both in terms of environmental criteria, as well as economic.