Influence of weather conditions and soil tillage treatments on weed infestation in winter wheat-soybean crop rotation.

One of the most important roles of soil tillage, especially conventional one, based on mouldboard ploughing, is the control of biotic factors, among them weed control. Research of influence of different soil tillage treatments on weed population in winter wheat crop has been undertaken at chernozem soil type in Eastern Croatia, during four years (2002-2005), with very different weather patterns. Eight soil tillage treatments, different in intensity of depth and frequency of soil tillage operations, were applied for winter wheat crop, in crop rotation after soybean. For each crop, four treatments had continuous soil tillage system (mouldboard ploughing tillage, diskharrowing tillage, chiselling tillage and no-till) and another four treatments had discontinuous soil tillage system (conventional tillage for one crop, and diskharrowing or no-tillage for another crop). The statistically significant differences were observed among soil tillage treatments in comparison with conventional one. Different weather patterns also showed significant differences in vertical and horizontal weed population distribution. Applied herbicides showed very high effectiveness in all tillage treatments.