Submitted to: Agronomy Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/9/2004
Publication Date: 1/1/2005
Citation: McLaughlin, M.R., Sistani, K.R., Fairbrother, T.E., Rowe, D.E. 2005. Effects of overseeding cool-season annuals on hay yield and nitrogen and phosphorus uptake by Tifton 44 bermudagrass fertilized with swine effluent. Agronomy Journal. 97:479-486. Interpretive Summary: In the southeastern US, waste from concentrated swine feeding operations is commonly flushed from animal production houses into large lagoons and the effluent sprayed over farm fields. Repeated applications of effluent, however, can lead to soil buildup of excess phosphorus (P). To reduce soil P, farm managers often grow bermudagrass hay crops to take up P for removal from the field. Bermudagrass, however, only grows during warmer months (May to September) and is dormant the rest of the year. In the work presented here, during a 3-yr study conducted on a private hog farm in Mississippi, the nutrient uptake season in a bermudagrass hay spray field was extended year round, hay yields and P uptake were increased, and pollution potential was decreased. This was accomplished by growing cool-season annual forage crops in the dormant bermudagrass. Planting cool-season annual forages in dormant bermudagrass, called overseeding, is often used in southern pastures to provide extra winter ground cover and earlier spring forage for grazing animals. In this study Tiff44 bermudagrass, grown for hay in a swine effluent spray field, was overseeded in the fall with cool-season annuals, including berseem clover, crimson clover, ryegrass and wheat. The annuals were harvested as hay the following spring, followed by summer harvests of Tiff44. Growth of the cool-season crops did not reduce yield or P uptake of the hybrid bermudagrass, but contributed extra forage in spring harvests, increasing total annual hay yields by 6 to 16 percent and P uptake by 2 to 13 percent, while reducing soil P. Berseem clover provided the greatest benefit. Overseeding hybrid bermudagrass with cool-season annual forages offers farm managers another way to boost hay yields and manage P in effluent spray fields.
Technical Abstract: Tiff44 bermudagrass [Cynodon dactylon (L.) Pers.] was seeded with cool-season annuals in a 3-yr study of DM yield and N and P uptake in a swine (Sus scrofa domesticus) effluent spray field. Treatments were berseem (Trifolium alexandrinum L.) and crimson (T. incarnatum L.) clovers, ryegrass (Lolium multiflorum L.), wheat (Triticum aestivum L.), and a standard practice (nonseeded) control on Mantachie soil (fine-loamy, siliceous, acid, thermic Aeric Fluvaquents) in a 3-yr-old stand of Tiff44 cut for hay and fertilized with effluent for 3 yr before the study. Soil NO3 and Mehlich-3 P (0-5 cm) were 267 and 82 mg kg-1, respectively, at the start of the study. Effluent was applied during the study (1.1 Mg N; 168 kg P ha-1). Plots seeded in fall were cut in spring for cool-season annual hay and in summer for bermudagrass hay. Spring berseem DM (4.4-5.5 Mg ha-1 yr-1) and P uptake (12.2-17.1 kg ha-1 yr-1) were higher than the control in 2 of 3 yr and higher than all other treatments in 2002. Spring berseem N uptake (94-122 kg ha-1 yr-1) was higher than the control each year and higher than other treatments in 2 of 3 yr. In summer the berseem treatment had higher DM in 2002 (4.9 Mg ha-1) and N uptake in 2001 (144 kg ha-1) and 2002 (86 kg ha-1) than other treatments. Summer Tiff44 control DM had a linear response to effluent N (Mg DM ha-1 = 0.0094 x kg N ha-1 + 2.8769, R2 = 0.99). Soil NO3 (0- 5 cm) after the study did not differ among treatments (mean = 35 mg kg-1), but Mehlich-3 P was less after berseem (49 mg kg-1) and more after wheat (130 mg kg-1) than after other treatments. No treatment adversely affected Tiff44 yield or nutrient uptake. Seeding with berseem clover increases annual DM yield and N and P uptake, decreases soil P, and offers a new tool to improve yield and nutrient management in Tiff33 spray fields.