Bosnia and Herzegovina, in part of Herzegovina, is characterized by a longer drought period during the summer season, due to the modified Mediterranean climate. The drought has been so far a “normal state” in Herzegovina. 

In addition to the high temperature, evaporation is affected by the water vapor pressure (the drier the air, the greater the evaporation). The wind further dries out the surface layer of the soil. 

However, according to information from Nada Rudan, head of the Climatology Department from the Republic Hydrometeorological Institute of Republika Srpska, many years of severe drought also has been shown in the north, where the largest crop production of the Republic of Srpska, Bosnia and Herzegovina is based. The severe drought for this region are not normal and they are considered as a climatic variation / anomaly, which repeats in the period from 50 to 70 years. The weaker droughts events have the shorter return period. 

2011 was the driest year in the last 140 years, while 2011 and 2000 were the driest during the crop growth period. 2003, 2017 and 2000 were the years with the driest summers based on the difference between evaporation / precipitation. 

According to data from the previous years, the summer of 2003 had the largest evaporation (525 mm evaporation / 135 mm precipitation), as well as the largest difference between evaporation / precipitation (390 mm) compared to the period from 2001 to 2018. After 2003, the driest years were 2017 and 2000, with a difference in favor of evaporation of 362 mm (478 mm evaporation / 116 mm precipitation). 

In the previous period, the minimum precipitation was recorded in 2015, then in 2013 and 2012. Less precipitation was registered only during the summer of 1950, 1946, 1933 and 1952. 

According to the data for Banja Luka, this was the driest June since 1862, with only 11.5 mm of precipitation. The previous absolute minimum was recorded in 1950 with 15 mm for the whole month. In terms of thermal conditions, June 2021 is the third warmest June in 140 years. It was warmer only in 2003 and 2019. 

Accordingly, the situation in the field UNI-BL shows a large differences in the maize crop growth at the Experimental Educational Center of the Faculty of Agriculture in Aleksandrovac. 

Plants that were provided with irrigation reached a height of up to two meters, while plants that were not irrigated, reached the crop height up to 50 cm lower compared to the irrigated ones. A huge differences can be also noticed in the fresh and dry mass, leaf area, as well as the number of leaves. 

In the next period, together with UNSA (Butmir) we will monitor the impact of drought and high temperatures, both on the vegetative and generative development of maize.