Monitoring of agricultural drought in tobacco growing areas in Poland in 2009-2017
Occurrence of unfavourable weather conditions (drought) causes significant losses in crop yields in the world. McKeown et al. , in their work on long-term climate patterns related to yields, stated that by 2030 the periodic occurrence of agricultural drought in crops will contribute to a 30 % reduction in yield. In Poland, the evaluation of agricultural drought has been implemented using the Agricultural Drought Monitoring System (ADMS), conducted by IUNG-PIB [Doroszewski et al. 2008, 2012]. ADMS uses the climatic water balance index (CWB) to monitor drought conditions in Poland.
In Poland, tobacco is grown mainly in the central-eastern and northern parts of the country. These are areas with a long tradition of growing this plant. In many cases, tobacco is grown on soils of the first category, which are highly exposed to water scarcity due to their internal structure and composition (they quickly dry out). The influence of unfavourable weather conditions (drought) undoubtedly contributed to the reduction of tobacco yields. The low CWB values recorded in reports showing a threat of drought have indicated the possibility of yield reduction in tobacco crops. At the same time, in the years when the CWB values did not reach the limit values and did not exceed them, an increase in the yield was demonstrated.
On the national scale, the yield of tobacco increased from 23 dt/ha in 2009 to 25.3 dt/ha in 2016. The high yield levels recorded in 2016 were undoubtedly largely due to meteorological conditions, in particular due to large atmospheric precipitation in August, which resulted in an increased tobacco biomass. Some of the yield increases could also be indirectly influenced by varietal progress, associated with increased resistance of plants to diseases and the development of a tighter plant canopy resulting in suppressed weed growth.