Nitrogen recovery and agronomic efficiency of forages with nitrogen fertilization under flooded condition

摘要

The cow-calf (Bos taurus) industry in subtropical United States and other parts of the world that depends almost totally on grazed pastures is facing several production constraints like changing climatic conditions and increasing cost of fertilizers, especially nitrogen (N). Particularly little is known about the response of forage species to the combined effect of water-logging and the addition of N. A two-year greenhouse study was conducted in 2008 and 2009 to determine i) the effect of flooding duration on N recovery and agronomic efficiency of bahiagrass (Paspalum notatum Fluegge) compared with two flooding tolerant forages, limpograss (Hemarthria altissima Poir), and maidencane (Panicum hematomon Schult) and ii) if N fertilization could mitigate the negative effect of flooding. Nitrogen recovery and agronomic efficiency varied significantly (P ≤ 0.001) among forage species. Averaged across levels of N, N recovery of bahiagrass and limpograss was reduced by about 41% and 56%, respectively after 84 d of continued flooding while N recovery of maidencane was slightly increase by about 5% between 0 and 84 d of flooding. Agronomic efficiencies of bahiagrass (41% to 26%) and limpograss (44% to 31%) were reduced by flooding while agronomic efficiency of maidencane was increased from 24% (no flooding) to 46% at 84 d of continued flooding. However, N recovery and agronomic efficiency of three forage species was positively affected by N fertilization. The overall N recovery of bahiagrass, limpograss, and maidencane ranged from 44% to 59%. Nitrogen fertilization could improve N recovery and agronomic efficiency of forage species under waterlogged condition.