Effect of preceding crop, soil tillage and herbicide application on weed and winter wheat yield

摘要

This article describes results obtained in three years of experiments (2001-2003) carried out at farm Dobele Agra SIA located in the Dobele region of Latvia. Trials were established in two different crop rotations (Factor A): 1. winter wheat sown after winter wheat, 2. winter wheat sown after winter rape. Three different soil tillage and sowing methods were compared (Factor B): 1. - minimal conservation soil tillage in 10-15 cm deep with mixing of soil; 2. - direct sowing into stubble without any previous soil cultivation; 3. - traditional soil tillage with ploughing on 25 cm with cultivation before sowing. Additionally we compared the impact of those soil tillage methods on weed infestation in winter wheat (Factor C): 1. - using herbicide Secator 0.3 kg ha~(-1), 2. - without herbicide treatment. A significantly smaller total number of weeds was observed in treatments where winter wheat was grown in recurrent sowing, primarily caused by differences in numbers of oil seed rape in this treatment. A significantly smaller number of weeds was also observed after traditional soil tillage with ploughing. Data analysis shows significant linear negative correlation between winter wheat yield and the number of total weed infestation and several weed species- Stellaria media (L.) Vill., Sinapis arvensis L., Matricaria perforata Merat. and Lamium purpureum L. The highest impact on changes of winter wheat grain yield was made by herbicide use - 64.1%.