Production and Natural Regeneration of Annual Medicago in West-Central Texas

Abstract

Several annual Medicago species have been found to be well adapted to the soils and climates of other areas of Texas, but their adaptation to west-central Texas has not been studied.  We evaluated the establishment, yield, and natural reseeding potential of Medicago truncatula, M. lupulina, M. polymorpha, M. minima, and M. orbicularis on a Rioconcho clay loam/Spur clay loam soil complex near San Angelo, Texas during 1998 – 2004.  All annual medics established following seeding in mid November 1998 although sub-freezing temperatures in December 1998 caused considerable seedling mortality.  With one irrigation in November 1998 and above-normal winter and spring rainfall, all species produced a good seed crop in spring 1999.  The medics did not establish in autumn 1999 because of dry conditions, but good establishment occurred in autumn 2000 following 8 in. of rainfall and a single irrigation in November 2000.  Frequencies of seedlings ranged from 61% for ‘Jemalong’ barrel medic (M. truncatula)  to 90%  for ‘Devine’ little bur medic (M. minima) in late March 2001.  Forage yields in early May 2001 did not differ significantly among the species, but ranged from 1250 (± 590) lb/acre for ‘Jemalong’ barrel medic to 2640 (± 610) lb/acre for ‘Estes’ button medic (M. orbicularis).  Yield from a late-October 2000 planting of ‘Devine’ little bur medic in May 2001 was 3060 (± 620) lb/acre.  ‘Devine’ little bur medic and ‘Estes’ button medic exhibited later maturation and tended to produce more forage than the other species.  Frequencies of medic seedlings in the November 1998 plantings were low (≤ 25%) while frequency of ‘Devine’ little bur medic in the October 2000 planting was high (63%) during February 2004 following multiple tillage operations and planting of wheat in September 2003.  Annual medics appear to have potential for improvement of rangelands and pastures in west-central Texas, but should be expected to produce significant forage amounts only in years with above-normal, cool-season rainfall or under irrigation.