Rye Cover Crop Management Affects Weeds and Yield of Corn (Zea mays L.)

In recent years, increasing application of chemical herbicides has raised concerns over their destructive impacts on living organisms and environmental health and it requires studies on non-chemical weed management methods. As a result, this experiment was initiated in November 2008 at experimental field of Islamic Azad University, Karaj Branch, in order to evaluate weed-suppressive ability of winter rye cover crop and mulch, and its effects on following corn yield production. Treatments included three rye seeding rates (500, 750 and 1000 kernels/m2) and three rye kill dates (29/3/2009, 15/4/2009 and 3/5/2009). In the fall 2008 rye was planted, then in the above three dates have been killed and left on the soil surface to provide mulching effect. Then in middle of June 2009, corn plants planted on the same plots of winter rye. Weeds density and biomass production were monitored in the fourth, sixth and eighth weeks after planting (WAP) corn. Corn yield production was also measured in late October 2009. Results showed that rye seeding rate has not affected weeds significantly but rye kill date had significant effect. The first kill date stimulated weeds germination and growth. The third kill date reduced density of all weeds in the fourth WAP on average 28.73% and their biomass production in the sixth WAP on average 21.38%. This treatment also increased corn grain production 7.89% at the end of the season. Finally, results of the experiment indicate that using cover crops should be combined with other methods to control weeds efficiently and to prevent yield production loss.