Overseeding Cool-Season Annual Forages in Coastal Bermudagrass Pastures on Dairies in Central Texas to Recycle Phosphorus John R. Bow & James P. Muir Stephenville INTRODUCTION Dairies 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 e MATERIALS & METHODS Species 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. RESULTS Dry 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 3 P K g/ha -1 P K g/ha -1 P K g/ha -1 R yegrass 10655 A 41 314 NS 1 10599 A 41 Barley 9219 B 36 1335 NS 5 9565 AB 37 R ye 7455 C 29 356 NS 1 6864 C 26 Triticale 8368 B 33 146 NS 1 7229 BC 28 Oats 7807 C 31 280 NS 1 8891 ABC 35 W heat 7748 C 31 1343 NS 5 9028 ABC 36 H airy Vetch 1021 D 4 0 NS 0 3732 D 13 A rrow leafclover 31 D 0 43 NS 0 866 E 2 Crim son clover 273 D 1 381 NS 2 754 E 3 R ose C lover 59 D 0 0 NS 0 685 E 2 B urrM edic 89 D 0 222 NS 1 823 E 3 0 0 Turnips 844 E 4 1150 NS 6 1023 E 5 Essex R ape 2283 D 10 1371 NS 6 2829 DE 12 DM K g/ha -1 DM K g/ha -1 DM K g/ha -1 Table 1. Cool-Season Species no-till drilled into Coastal Bermudagrass Year1 Year2 Year3 0 100 200 300 400 500 600 700 mm O ctoberthru M ay RainfallTotals Hairy Vetch Rose clover Arrowleaf clover