The objective of the work, carried out as part of research programme on current change of the regional climate, was to confirm the hypothesis about the increasing frequency and intensity of droughts in May and June in the region of Kujawsko-Pomorskie (central Poland) in the years 1981 – 2010. Furthermore, the aim was to confirm a significant relationship between indicators characterizing meteorological and agricultural droughts. Material for the research was the data from five meteorological measuring points located in the region. Atmospheric precipitation and air temperature in the period of high water needs of cereals and rapeseed (May–June) were used. Statistical methods widespread in climatological studies were applied, particularly the method of trends. The average multiannual totals (1981–2010) of rainfall in May–June allow ranking the region of Kujawsko-Pomorskie into the area of the lowest rainfall in Poland. The frequency of meteorological drought in May and June is 23.3–30.0% in the region. In the analysed period there were no significant changes in the frequency and intensity of these droughts with the passage of years. Rainfall shortages in cereal crops and rapeseed production range on average from -19 to -35 mm, and extend to maximum of -93 to -117 mm. The values of shortages did not show any significant changes in the years of the study. The significant dependence between the indicators of meteorological and agricultural droughts allows for determination of the rainfall shortages in crop production on the basis of the SPI values.

The most important reason for growing field crops is food consumption. Only some of the total amounts of field crop species are mostly used for cultivation in the largest part of arable land. These crops ensure high economic income. This is the reason why biological diversity has decreased. Crop rotation is considered to be an instrument of sustainable cropping system and this is confirmed again nowadays. Higher cereal yields have been gained by including oil crops or pulses in the rotation. Each field crop has its own calorific value (MJ kgE-1). Grains/seeds and above-ground biomass may have different calorific values because of their chemical composition. Research results from literature confirm that the average net calorific value of winter wheat (Triticum aestivum) and triticale (Triticosecale) grain and straw are ~17 MJ kgE-1, but the net calorific values for oilseed rape (Brassica napus ssp. oleifera) seeds and straw are – 25.70 MJ kgE-1 and 16.37 MJ kgE-1, respectively. Oilseed rape is also known as energy rich crop. It is reported that diversified crop rotations also have greater energetic productivity from above-ground biomass (grain/seed yield and by-products) if compared with crops grown in repeated sowings or in monoculture. Crop rotation in combination with different tillage methods (conventional tillage, reduced or minimum tillage and no-tillage) is the way to improve soil quality, but it is not clear whether the soil treatment method has a significant impact on the overall crop rotational energy productivity.

The objective of this article is to assess farm efficiency and productivity change in specialised large farms located in the region of Mazowsze and Podlasie during the years 2014 − 2016. For this, we used the non-parametric Data Envelopment Analysis (DEA) method and Malmquist index. Calculations were performed for three types of large farms classified as: field crop, pig and dairy. The study shows that mean technical efficiency of large field crop, pig and dairy farms amounted to 80, 75 and 70%, respectively. Technical inefficiency of field crop farms come mainly from scale efficiency, while of pig and dairy farms equally from pure technical and scale efficiency. It shows that inefficient management practices had an impact on farm performance. Therefore, in order to increase competitiveness of farms, an improvement of management practices is required. In the studied period the share of farms operating under increasing return was as follows: 67, 72, and 81%, respectively for field crops, pig and dairy farms. The improvement of efficiency of those farms could be achieved by increasing their size. The results indicate that 8% of field crops, 12% of dairy and 16% of large pig farms were operating under decreasing scale efficiency, which means that those farms were operating above the optimal scale. The increase in their efficiency could be achieved through size reduction. In dairy farms the average annual productivity growth of 2% was recorded. In pig farms the productivity reduction of 5.4% was observed. It was the result of a decrease in technological efficiency.