Grazing‐Tolerant Alfalfa Cultivars have Superior Persistence under Continuous and Rotational Stocking

Abstract

Grazing-tolerant alfalfa (Medicago sativa L.) cultivars are developed and evaluated under continuous stocking, but this does not reflect the grazing method used by most farmers. The objective of this experiment was to compare persistence of grazing-tolerant and intolerant cultivars grown in pure stands under continuous and rotational stocking in central Iowa. Small-plot trials were established in 2001 using the tolerant cultivars ‘Alfagraze’ and ‘Samurai’ and the intolerant cultivars ‘Apollo’ and ‘5454.’ Plots were not grazed in 2001, but continuous or rotational stocking was applied from mid-May through mid-September in 2002 and 2003. All cultivars had similar stands at the end of the establishment year. Under continuous stocking, the tolerant cultivars had superior survival after 1 year compared with the intolerant cultivars, but no differences among cultivars were seen under rotational stocking after the first year. After the second year of grazing, tolerant cultivars had superior persistence compared to the intolerant cultivars under both stocking methods. This supports a conclusion that evaluation under continuous stocking accurately reflects the performance of cultivars under rotational stocking. Given that continuous stocking allows faster separation of cultivars, it should be the preferred method of evaluation.