66 Srđan Šeremešić, Ivica Đalović and Dragiša Milošev
(wheat–maize) MW-F; fertilized wheat monoculture WW-F; unfertilized 3–
year rotation (wheat–maize–soybean) MSW, and unfertilized 2–year rotation
(wheat–maize) MW. The unfertilized treatments were established 1946/47,
and fertilized in 1969/70. Conventional tillage practice including moldboard
plough (30 cm), harrow disc, and cultivator was performed every year. Harvest
residues were incorporated by plowing. Winter wheat sowing was done in
October (20–30. X) with seeding rate of 250 kg ha–^1 and with 100 kg N ha
year-^1 while P and K are applied based on the soil analyses. During the
observed period the leading varieties of winter wheat, soybean and spring
barley and maize hybrids were grown.
The data on climatic characteristics indicate semiarid conditions of the
study area with an uneven precipitation distribution over the vegetation season
(Figure 1). During the last two decade average year temperature increased and
sum of precipitation slightly increased. The critical period for winter wheat
growing is considered to be in May, Jun when lack of precipitation could
affect production and regular heat stress influences winter wheat ripening.
Therefore, we assume that climatic conditions and particularly temperature
could have a prevailing effect on winter wheat growing, yield formation and
stability. Of particular interest is monthly temperature raise in Jun and July
when above average rainfall were not sufficient to compensate
evapotranspiration and could cause severe draught.
Figure 1. Average precipitation (P) and temperatures (T) at the experimental station
Rimski Šančevi.
0102030405060708090100- 5
0510152025X XI XII I II III IV V VI VII VIII IXTemperature Precipitation (mm)ºCP (mm) 1970/1990 P (mm) 1991/2010
T (ºC) 1970/1990 T (ºC) 1991/2010