Influence of Tillage and Crop Rotation Systems on Economy and Weed Density in a Semi-arid Region

A long-term rotation experiment was established in ۲۰۰۱ to compare conservation or reduced tillage systems (shallow rototiller and chisel tillage) with conventional tillage system using mouldboard plough in a semi-arid region with Mediterranean climate. Field experiments were conducted to determine weed density and profitability of cropping systems in a crop rotation of winter wheat (Triticum aestivum L.)-winter vetch (Vicia sativa L.) from ۲۰۰۱ to ۲۰۰۴ and winter wheat-winter vetch/summer maize (Zea mays L.) from ۲۰۰۴ to ۲۰۰۹. Results indicated that, rototiller markedly increased total weed density, as compared with mouldboard plough, by ۷۲% and ۵۸% in maize and vetch, respectively, while total weed density was statistically similar for the three tillage systems in wheat. Maize yield was significantly higher for rototiller and the lowest for chisel compared to mouldboard plough, but, there were no significant differences in wheat yield between the two tillage systems. Chisel and mouldboard plough resulted in a high yield of vetch in the last five years of the vetch growing season, but there were no significant differences in yield between tillage systems in the first three growing seasons of the crop. Based on market returns, gross margin over production costs were significantly higher for rototiller in wheat and maize when compared with mouldboard plough by ۲۰.۷% and ۱۵.۳%, respectively. Chisel production costs were similar to rototiller and lower than plough; but, chisel had a gross margin similar to mouldboard plough and higher than rototiller, in both vetch growing seasons. Time savings were ۴۳% and ۴۷% for rototiller and chisel, respectively, as compared with plough in wheat. The corresponding values in vetch and maize were, for rototiller, ۴۶% and ۵۰%, and, for chisel, ۲۸% and ۳۲%, respectively.