Spring growth of lucerne (Medicago sativa L.) after different winter grazing regimes

Abstract

This experiment determined if the removal of basal buds by grazing in autumn/winter affected the spring growth or development of lucerne. Established at Iversen Field Lincoln University, New Zealand and the experiment ran from the 1^st of June 2024 to 1^st of October 2024 (122 d). Four grazing dates (1^st of June, 3^rd of July, 17^th of July, and the 1^st of August) were were applied by mob stocking mixed age Coopworth ewes to simulate a “clean-up” winter graze. The start of rapid stem extension in spring occurred at a photoperiod of 10.8 (± 0.2) hours for all treatments. However, shoot biomass differed at each harvest until the 3^rd of September. Taproot yield was highest in crops grazed on the 1^st of June (3300±124 kg DM/ha) and lowest (1100±124) kg DM/ha) in the latest (1^st of August) grazing date at the final harvest on the 1^st of October. Results suggested that spring shoot biomass production was unaffected by winter grazing date. However, the ~1000 kg DM/ha lower root yield for lucerne grazed on 1^st August meant the crop would require a longer period of autumn recovery to recharge reserves to maintain stand persistence.