Effect of tillage on weed seed bank and weed flora in maize ('Zea mays')

The weed seed bank and above-ground weed flora were studied in a maize cropping system at the University of New England in Armidale, Australia, using no-till (NT), chisel plough (CP) and mouldboard plough (MP) tillage systems, in weed-free and weedy conditions. Tillage effects on weed seedbank size were assessed by the seedling germination method in soil samples from 0-5, 5-10, 10-15 and 15-20 cm depths in a glasshouse. Above-ground weed flora was assessed as seedling emergence in the field. Tillage systems affected both the weed seed bank and seedling emergence in the field. CP and MP triggered emergence of broadleaf weeds resulting in more weeds in the top 5 cm layer under weedy conditions. Fewer weeds emerged in NT under weedy conditions and maize yield under this system was higher than in CP and MP. Under weed-free conditions, maize yields were similar across the tillage systems. Weed seed bank size at the 0-5 cm depth was largest in the NT (559 seeds m⁻²) and smallest in the CP treatment (232 seeds m⁻²) under weed-free conditions.