Forage, Nitrogen, and Phosphorus Yield Dynamics of Cool‐Season Annual Forages Overseeded onto Tifton 85 Bermudagrass

Abstract

MATERIALS AND METHODSAn on-dairy trial was performed from 2005 to 2007 near Dublin, TX (32°15' N, 98°12' W, altitude 395 m) on an established 5-yr-old stand of Tift on 85 with a history of dairy manure application. Th e soil in the experiment area was a Windthorst fi ne sandy loam (pH 7.7, 83 mg P kg -1 , 249 mg K kg -1 , 1770 mg Ca kg -1 , and 147 mg Mg kg -1 using the Mehlich III extractant method; Mehlich, 1984). Th ese values were stable from year to year. Adjacent but distinct experiment sites under the same pivot each year were seeded with 13 annual cool-season ABSTRACT 'Tift on 85' bermudagrass [Cynodon dactylon L. (Pers.) X C. transvaalensis Burt Davy] is a warm-season forage used on southeastern U.S. dairy concentrated animal feeding operations (CAFO). Cool-season annual forages need to be identifi ed that can be overseeded into Tift on 85 and remove the greatest quantity of P or N while minimizing suppression of bermudagrass spring regrowth. During 3 yr we overseeded six grass, fi ve legume, and two Brassica spp. on a dairy CAFO Tift on 85 fi eld on a Windthorst fi ne sandy loam (fi ne, mixed, active, thermic Udic Paleustalf) containing 83 mg plant-available P kg -1 soil. Hairy vetch (Vicia villosa Roth.), barley (Hordium vulgare L.), oat (Avena sativa L.), and rye (Secale cereale L.) yielded the most (entry × year interaction P < 0.05) dry matter (DM) during at least 2 of the 3 yr, with the grasses and some legumes reducing (entry × year interaction P < 0.05) spring fi rst-harvest Tift on 85 DM yields by 41 to 80%. Cumulative cool-season and fi rst-harvest Tift on 85 P yields increased (entry × year interaction P < 0.05) in some combinations and years compared to Tift on 85 alone, while N yields rose up to 173% when legumes were overseeded, depending on year and combination (entry × year interaction P < 0.05). Results indicate that overseeding some cool-season winter annual forage species onto dormant Tift on 85 can increase N for CAFO feed but only occasionally will it improve P removal.

Overseeding Cool‐Season Annual Legumes and Grasses into Dormant ‘Tifton 85’ Bermudagrass for Forage and Biomass

“…Except for N fertilizer in 2009-2010, grass-hairy vetch mixtures yielded greater DM than other treatments when averaged over all grass entries in the forage harvest both years. Other studies reported greater hairy vetch forage yields when overseeded as a monoculture into dormant bermudagrass compared with similar annual cool-season legumes, except during dry spring conditions (Muir and Bow, 2011;Freeman et al, 2016). In our study, plots containing hairy vetch had forage yields 40 and 290% greater than crimson clover and the control, respectively, in 2009-2010.…”

“…Nitrogen fertilizer applied to cool-season grasses harvested as forage resulted in the greatest spring first-cut Tifton 85 DM yield. This may indicate residual soil N or less spring competition for soil moisture and solar irradiation in the absence of legumes, as is reported in legume-monoculture studies by Freeman et al (2016) and Muir and Bow (2011), in which spring first-harvest bermudagrass yields were lower when overseeded with cool-season legumes the preceding winter compared with no-legume controls. Research by Han et al (2012) (Muir and Bow, 2011).…”

“…or crimson clover (Trifolium incarnatum L.) can increase total yearly pasture forage yield from 17 to 22%, respectively, and improve bermudagrass yields by 18% vs. grass without clover treated with 224 kg N ha −1 (Knight, 1970). In addition to green chop or haylage, cool-season forages planted into bermudagrass sod could potentially contribute cellulosic bioenergy and provide an additional option for removing excess dairy manure nutrients from application fields (Muir and Bow, 2011). Biofuel research is gaining momentum, mostly focused on using warmseason (C 4 ) forages such as switchgrass (Panicum virgatum L.; Cassida et al, 2005), with minimal research using cool-season annual plants for eventual biofuel production.…”

“…Under irrigation, dairymen or future bioenergy feedstock producers may also choose to use dormant bermudagrass [Cynodon dactylon (L.) Pers.] sod as a seedbed for their cool-season forages (Muir and Bow, 2011). Overseeding bermudagrass sod with annual cool-season grasses can improve yearly forage production per unit area (Fribourg and Overton, 1973).…”

Winter Annual Legumes Overseeded into Seeded Bermudagrass ( Cynodon dactylon ): Productivity, Forage Composition, and Reseeding Capability

“…The other legumes maintained their DM yield into sequence 3 and did not senesce as rapidly. The literature reports both lower (Muir and Bow, 2011) and higher (Brink et al, 2001) yields for the same species of legumes. Chamblee and Mueller (1999) obtained yields of 4685 kg/ha for CC, 2903 kg/ha for AC, and 4303 kg/ha for HV, similar to those seen in this study, suggesting the yields we obtained are typical.…”