The implication of stubble tillage for weed population dynamics in organic farming

Summary

In practical farming early and shallow stubble tillage post-harvest is carried out to stimulate germination of freshly ripened crop and weed seeds, to kill the resulting seedlings and hence to reduce the input into the soil seedbank. Additionally, it aims at reducing perennial weeds by mechanical damage. In this paper field experiments and laboratory studies are presented which show that stubble tillage can reduce perennial weeds. However, it had a variable effect on annual weeds. After five years of experimentation, no effect of stubble tillage was seen when looking at the aboveground vegetation. In contrast, the soil seedbank of the control roughly doubled the seedbank of plots where stubble tillage had been carried out immediately after harvest. These results indicate that practical experience may be correct which assumes that stubble tillage reduces annual weed populations, despite the fact that in other published studies stubble tillage exerted no control of annual weeds or had a variable effect.