Overseeding Cool-Season Annual Forages in Coastal Bermudagrass Pastures on Dairies in Central Texas to Recycle Phosphorus

John R. Bow & James P. Muir Stephenville

INTRODUCTIONDairies in north-central Texas containing high-phosphorus soils resulting from the application of waste water and manure can recycle nutrients by over-seeding Coastal (Cynodon dactylon (L.) Pers.) bermudagrass fields with cool-season annual forages. Ryegrass (Lolium multiflorum Lam.), barley (Hordeum vulgare L.), rye (Secale cereale L.), triticale (Triticum secale L.), oats (Avena sativa L.), wheat (Triticum aestivum L.), hairy vetch (Vicia villosa Roth), burr medic (Medicago polymorpha L.), arrowleaf clover (Trifolium vesiculosum Savi.), rose clover (Trifolium hirtum All.), crimson clover (Trifolium incarnatum L.), turnips and rape (Brassica spp.) were evaluated for winter forage yields.

OBJECTIVES

•Recycle soil-P via a winter forage crop

•Provide high quality winter/spring green chop

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MATERIALS & METHODSSpecies were no-till seeded into 1.5 X 5 m plots in early fall of 2004, 2005 and 2006. Cool-season grass and brassica plots received 56 kg ha-1 nitrogen in mid winter. Species were individually harvested in the spring when the cool-season grasses were in boot stage and the forbs flowered. Soil analysis showed a pH 8.4, and 188 ppm P, 35 N, 717 K.

RESULTSDry matter and P yields were affected by year x species interactions (P < 0.0001). Cool-season grasses were the most productive in DM yield and P extraction in years 1 and 3 (28 to 41 kg P ha-1). Year 2 DM yields were negligible in the Coastal pastures due to insufficient rainfall. Hairy vetch was the most productive legume, resulting in up to 13 kg P ha-1 extracted year-1.

CONCLUSIONS

•Overseeding cool-season forages on dormant bermudagrass can extract up to 41 kg ha-1 P in growing seasons that have sufficient rainfall.

•Over-seeding is poor investment in dry years.

Funding provided in part by:

•Texas AgriLife Research•Texas State Soil & Water Conservation Board•National Integrated Water Quality Program, AFRI

Crimson clover

Burr medic

YEAR 1 YEAR 2 YEAR 3P Kg/ha -1 P Kg/ha -1 P Kg/ha -1

Ryegrass 10655 A 41 314 NS 1 10599 A 41Barley 9219 B 36 1335 NS 5 9565 AB 37Rye 7455 C 29 356 NS 1 6864 C 26Triticale 8368 B 33 146 NS 1 7229 BC 28Oats 7807 C 31 280 NS 1 8891 ABC 35Wheat 7748 C 31 1343 NS 5 9028 ABC 36

Hairy Vetch 1021 D 4 0 NS 0 3732 D 13Arrowleaf clover 31 D 0 43 NS 0 866 E 2Crimson clover 273 D 1 381 NS 2 754 E 3Rose Clover 59 D 0 0 NS 0 685 E 2Burr Medic 89 D 0 222 NS 1 823 E 3

0 0Turnips 844 E 4 1150 NS 6 1023 E 5Essex Rape 2283 D 10 1371 NS 6 2829 DE 12

DM Kg/ha -1 DM Kg/ha -1 DM Kg/ha -1

Table 1. Cool-Season Species no-till drilled into Coastal Bermudagrass

Year 1

Year 2

Year 3

0

100

200

300

400

500

600

700

mm

October thru May

Rainfall Totals

Hairy Vetch

Rose clover Arrowleaf clover