62 Srđan Šeremešić, Ivica Đalović and Dragiša Milošev
Long-term mouldboard tillage has influenced physical soil properties and
particularly altered soil structure. As a consequence of sufficient
fertilization, the considerable content of available P 2 O 5 (24-63 mg 100g
soil-^1 ) and K 2 O (33-39 mg 100g soil-^1 ) were present in the topsoil. In
contrary, unfertilized plots were not sufficiently supplied with the
available P but maintained available K content. Soil organic carbon
(SOC) decreased because of soil inversion tillage to 65% of the original
content observed at the begging of the experiment. Likewise, SOC
equilibrium at the unfertilized plots was established after 25 years of the
experiment running. Winter wheat monoculture was higher in the content
of total N and soil organic carbon (>16 g kg-^1 ), which could be explained
with preservation of physical soil properties and available water. By
analyzing the long-term yields, it was found that there is certain stability
in yields at some level and relatively small annual variation. In a time
span of the experiment management yield of winter wheat decreases at
the 3-year rotation while wheat monoculture increase yield over time.
Hence, most stabile wheat yield was observed at the 3-year rotation
suggesting important role of the preceding crops and legumes (soybean)
in rotation. This study could contribute to gain awareness of winter wheat
role in a cropping systems of the temperate climate and to understand the
relationship between wheat based cropping and soil properties.Keywords: winter wheat, long-term experiment, grain yield, crop rotation,
Chernozem
INTRODUCTION
Winter wheat is an adaptable crop that can be successfully grown on many
soil types and under many environmental conditions, including contrasting
agronomical practices. Thus, wheat-based crop rotation is a common cropping
option for field crop production in many developing countries. The Southern
Pannonian Basin (Province of Vojvodina) has a long history of winter wheat
growing. Traditionally, winter wheat is one of the most important crops, but it
has often been grown on poor soils with the lower inputs compared with the
row crops (Molnar, 2003). In addition to that, winter wheat cropping has
undergone several stages of development, based on the introduction of new
cultivars (Denčić et al., 2009) although intensity of the cropping management
has been less improved, compared with the row crops. As a result of
improvements in breeding programs and identification of high-yielding
genotypes, winter wheat yields increased in the 1970s (Denčić et al., 2008), as