ESTABLISHMENT OF LUCERNE AFTER MAIZE IN CONSERVATION TILLAGE SYSTEMS

Extensive slug damage reported for lucerne (Medicago sativa L.) establ ishment in grass sod and small grain fields when using conservation ti llage prompted this 3-year study on establishing lucerne in maize (Zea mays L.). Different crop residues were created by harvesting maize fo r grain and silage and including a silage+rye (Secale cereale L.) wint er cover crop treatment. Conventional tillage (ploughed in spring) fol lowing grain harvest was included as a control. In addition, a combina tion treatment of methiocarb bait broadcast on the surface and carbofu ran 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 yi elds, especially the silage+rye residue treatment, which caused the lo west lucerne yields. Highest yields of lucerne occurred when it was pl anted after silage, a treatment in which residue was minimal. The earl iest planting date gave the highest lucerne yields in the establishmen t year. Slugs did not reduce the establishment of lucerne in any maize residue, nor were lucerne yields affected by slug feeding. This was a ttributed to the low slug populations observed early in the growing se ason. Establishing and producing lucerne in maize residues was more su ccessful in this study because of the lower slug populations than thos e usually encountered in grass sod or small grain residues.