Weather conditions and yields of maize in Federation of Bosnia and Herzegovina with emphasis on Tuzla Canton

In the 15-year period 2000-2014 maize was grown in Federation of Bosnia and Herzegovina (FB&H) on the area of average 61405 ha (maize for grain 48208 ha and green maize 13197 ha). Average yields of maize for grain was 3.99 t/ha with considerable variation among the years from 2.18 to 4.92 t ha-1. In three “the poor” years (2000, 2003 and 2012) yield was less than 3.0 t/ha (average 2.66 t ha-1), while in three “the good” years (2006, 2008 and 2009) it was above 4.5 t ha-1 (average 4.74 t ha-1). Precipitation quantity in the April – September period of “the poor” years in Tuzla was 320 mm (3-year average) or 39% of the long-term mean (LTM) 1961-1990, while in “the good” years it was 492 mm. Mean air-temperature at the same period of the favorable years was 17.5 oC or for 1.0 oC lower than in the unfavorable years. The most unfavorable for maize growing in FB&H and the wide region were the growing seasons 2000 and 2012. Precipitation in April – September period (Tuzla) of 2000 was only 282 mm or 54% of LTM. Also, in three summer months (June-August) precipitation was only 98 mm or third part of LTM, while air-temperature was 22.0 oC or for 4.0 oC higher than LTM. Under these unfavorable conditions, maize yield in FB&H was only 2.18 t ha-1. The growing season 2012 was similar to 2000 and especially dry was in July and August (8 mm precipitation and mean air-temperature 23.6 oC or for 4.2 oC above LTM). Maize yields in Tuzla Canton in 2005 - 2012 period were in range from 2.6 t ha-1 in 2012 to 4.4 t ha-1 in 2008 and 2009. However, by statistical analysis were found significant negative correlation only between yield and monthly temperature as follows: August -0.68** , April-August -0.52* (in FB&H), June -0.62*, July -0.72** (in TC). Alleviation of unfavorable effects of “poor” years for maize yields is possible by irrigation and by adequate soil management (ploughing and addition of majority NPK fertilizers in autumn instead of spring, weed control, growing more drought tolerant hybrids etc.).