Title: Winter Cover Crop Responses to Nitrogen Fertilization in a Swine-Effluent Spray Field Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 3, 2010
Publication Date: October 31, 2010
Citation: Read, J.J., McLaughlin, M.R., Brink, G.E., Sistani, K.R. 2010. Winter cover crop responses to nitrogen fertilization in a swine-effluent spray field. Agronomy Abstracts. Paper #82-5. CD-ROM. Technical Abstract: For the sustained, safe use of swine effluent spray fields, the annual management of nutrients is critical, not just the summer yields. Studies were conducted at a commercial swine farm to determine the effects of 0, 50, 100, 150 kg N/ha (applied as 34-0-0 in spring) on spring and annual dry matter (DM) yield and nutrient uptake by bermudagrass alone and bermudagrass overseeded with annual ryegrass, cereal rye, or berseem clover. Our hypothesis was that even with repeated manure applications in summer (April–Sept.), N availability limits DM yield. Crop growth and N responses differed between years, probably due to lower effluent application rate in 2000 (3.6 ha cm) than 2001 (7.1 ha cm, which is more typical for the area). Overseeding bermudagrass enhanced annual DM yield by about 4.9% in 2000 and 0.4% in 2001. Averaged across three harvest dates, N rate and cover crop effects on DM yield were significant (P<0.05) in 2000, without a significant rate by crop interaction. At the first harvest in spring, herbage N concentration increased as N rate increased in 2000 and averaged approximately 15, 17 18, and 21 g/kg across rates; values did not differ in 2000 and averaged approximately 22, 22, 25, and 27 g/kg. The relative yield, defined as DM yield at a given N rate divided by the maximum observed DM yield, varied from 77 to 98%, suggesting N nutrition was not strongly limiting, even at the lowest fertilization rate. Overseeding bermudagrass with annual ryegrass increased annual N removal by 3 to 13%, and the use of 100 kg N/ha resulted in high removal rates.