Seeding Rate, Phosphorus Fertilization, and Location Effects on ‘Armadillo’ Burr Medic

Availability of the recently developed cultivar Armadillo provides opportunity for use of burr medic ( Medicago polymorpha L.) in the south‐central USA where the species has become extensively naturalized. Area of adaptation and effects of seeding rate and P fertilization were identified as insufficiently understood aspects of this cultivar that could potentially determine success of Armadillo burr medic plantings within the region. Thus, objectives were to assess adaptation of this cultivar to both cooler and more humid locations than the south Texas origin of the cultivar and to evaluate effects of initial seeding rate and P fertilization. Neither seeding at 11 or 22 kg ha −1 nor fertilization with 0 or 25 kg P ha −1 affected forage accumulation, which was greater ( P < 0.05) in the initial year at Alexandria, LA (3330 kg ha −1 ) than at Rosepine, LA or Stephenville, TX. Seed production, critical for reseeding, was greatest ( P < 0.05) at Stephenville, with 344 kg ha −1 , and increased with P at the high seeding rate only. Soil seed reserves 11 mo after seed set was 44% of the initial seed crop at Stephenville and <20% at the two, more‐humid Louisiana sites. On the sites represented, yield potential may limit Armadillo primarily to extensively managed systems. Such systems include livestock production and wildlife in the drier western extent of the region, but they primarily involve plantings for wildlife in the eastern portion of the region. High seeding rates with P fertilization can contribute to seed production and enhanced opportunity for stand regeneration.