Establishment of lucerne after maize in conservation tillage systems†

Extensive slug damage reported for lucerne ( Medicago sativa L.) establishment in grass sod and small grain fields when using conservation tillage prompted this 3-year study on establishing lucerne in maize ( Zea mays L.). Different crop residues were created by harvesting maize for grain and silage and including a silage+rye ( Secale cereale L.) winter cover crop treatment. Conventional tillage (ploughed in spring) following grain harvest was included as a control. In addition, a combination treatment of methiocarb bait broadcast on the surface and carbofuran granules applied in the furrow with the seed was compared with an untreated control. Finally, three planting dates, early and late April and late May, simulated the spring planting season. Planting lucerne in the different maize residues had a significant effect on lucerne yields, especially the silage+rye residue treatment, which caused the lowest lucerne yields. Highest yields of lucerne occurred when it was planted after silage, a treatment in which residue was minimal.
The earliest planting date gave the highest lucerne yields in the establishment year. Slugs did not reduce the establishment of lucerne in any maize residue, nor were lucerne yields affected by slug feeding. This was attributed to the low slug populations observed early in the growing season. Establishing and producing lucerne in maize residues was more successful in this study because of the lower slug populations than those usually encountered in grass sod or small grain residues.