Light Penetrating a Bahiagrass Canopy and Its Influence on Establishing Jointvetch1
- R. S. Kalmbacher and
- F. G. Martin2
Bahiagrass (Paspalum notatum Fligge) is important in the southeastern USA and is Florida's major perennial grass, but low protein content and digestibility can limit cattle performance. Mixing bahiagrass with a legume such as jointvetch (Aeschynomene americana L.) would improve animal grazing performance. This 3-year study was conducted at Ona, Fla. (27°25 N, 8l°55 W) on a sandy, siliceous, hyperthermic Alfic Haplaquod to determine the effect of light on legume seedling establishment and yield to develop management guidelines that would enhance seeding success. Bahiagrass was treated each year by: i) spraying paraquat (1,l' dimethyl-4,4' bipyridinium dichloride) at 0.56 ai. kg . ha−1, desiccating for 72 h, then burning the residue and drilling seed into the sod; ii) disking sod three times followed by broadcasting seed; iii) grazing to 3 to 5 cm stubble, drilling seed and grazing until jointvetch was 2.5 cm tall; iv) spraying glyphosate [(N-phosphonomethyl) glycine] at 0.84 a.i. kg. ha−1 in 15 cm wide bands, 22.9 em apart, drilling seed; v) spraying dalapon (2,2 dichloropropionic acid) at 3.32 kg. −1 in 15 cm wide bands, drilling seed; vi) drilling seed in untreated hahiagrass (check). More light penetrated through the canopy of the paraquat-hurn (21 to 33 E m−2 day−1) and graze treated (20 to 30 E m−2 day−1) bahiagrass than in any other treatment. These treatments also had the greatest number of seedlings (3-year average was 86 m−2), the highest dry matter yield of jointvetch (2,200 kg ha−2), and they produced the grass-legume mixtures with the highest protein content (10.6%) and digestibility (49.1 %). Glyphosate treated sod allowed 17 to 24 E m−2 day−1 to penetrate the canopy, and good legume stands developed (80 seedlings m−2). The canopy from dalapon and check treatments was too dense (7 to 20 E m−2 day−1) to permit good legume establishment. Studies with saran shade screen indicated that 45% incident light, 20 E m−2 day−1, was the minimum light level for good jointvetch establishment. These data indicated that grazing was the most practical and successful method of removing and controlling the hahiagrass pasture canopy during legume establishment.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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