engleski

Precipitation influences on maize yields in Eastern Croatia

Considerable variation of maize grain yields among years as well as among different parts of Eastern Croatia for 30-year (1961-1990) period and for 1996-2003 period were found. Increased yield trends for long period is possible to explain by improvement of crop and soil management practices as well as creating of high-yielding hybrids. Affected by soil characteristics, higher grain yields of maize were found in the eastern part of the region compared to its western part. For example, mean grain yield of maize in the Donji Miholjac (DM) and Podr. Slatina (PS ) was 22% lower than in Vukovar (VU) and Osijek (OS) area (5.84 and 4.58 t ha-1, respectively). Differences of maize yields were found between VU and PS areas (6.00 and 4.14 t ha-1, respectively). Yield differences in the same period for individual parts of province could be explained only by soil factors, since weather conditions, soil and crop management practices as well as choice of maize hybrids are similar for the region. Weather differences among individual growing seasons are more responsible factor of maize yields for a short period. For example, in the three more favorable seasons (MFS=1982, 1984 and 1986) mean maize yield in the region totaled 6.69 t ha-1, whereas in the three less favorable seasons (LFS=1978, 1980 and 1988) it was 5.11 t ha-1 or 24% lower. Analogical data for the VU area were 7.94 and 6.38 t ha-1 and for PS area 5.34 and 4.14 t ha-1, respectively (Table 1). The amount of precipitation for 4-month period (May-August) was lower in the LFS (3-year means for four tested localities: 285 and 237 mm, for the MFS and LFS, respectively), whereas at the same time precipitation in July was nearly 40% lower (65 and 40 mm, respectively). In the 1996-2000 period, maize harvested area in the region decreased about 20% in comparison with 10-year mean of 1981-1990, whereas yields showed mild increasing trend. Since 1996 yield variation among years, as well as its dependences on water regime had similar trend as in the previous tested periods. Especially low maize yield in the region in 2000 (34% lower in comparison with four previous years) is mainly influenced by water shortage. For example, the amount of precipitation in Osijek for the period May-August in 2000 was 107 mm or only 40% in comparison with 30-year mean (1961-1990). Under these environmental conditions, maize yield differences between more fertile aerated soils of the eastern part of the region (e.g. VSc area) and less fertile compacted soils in its western part (e.g. VPc area) are very small (Table 3). Main reason for this phenomenon is better ascent of underground water in compacted soils. The 2003 growing season was especially unfavorable for maize growing because of water shortage. For example, precipitation in 4-months May-August period was only 162 mm (the data of Osijek Waether Bureau) and it is for 40% lower in comparison with 30-years mean (1961-1990). Under these conditions, maize yield in Eastern Croatia (Table 3) was only 4.53 t ha-1 or 37% lower in comparison with previous year (7.21 t ha-1). Yield difference between 2002 and 2003 growing season is mainly affected by precipitation quantity (May-August: 368 and 162 mm, for 2002 and 2003, respectively).

precipitation; maize yield;

nije evidentirano