|Cavadini, Jason - University Of Wisconsin|
Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/20/2015
Publication Date: 7/12/2015
Citation: Coblentz, W.K., Jokela, W.E., Cavadini, J.S. 2015. Fertilization of fall-grown oat with dairy slurry or urea. Journal of Dairy Science. 98:50.
Technical Abstract: Oat has shown promise as a fall-forage option for dairy producers in Wisconsin. Our objectives were to assess the effects of summer applications of urea fertilizer or dairy slurry on the DM yield, N uptake, and apparent N recovery from fall-grown oat forages. ‘ForagePlus’ oat was established in early-August of 2013 and 2014, and fertilized with 0, 20, 40, 60, 80, or 100 kg N/ha as urea (46-0-0), or dairy slurry applied at rates of 43,250 (LM) or 86,500 L/ha (HM). All plots were harvested during early-November of each year. Yields of DM increased in response to fertilization with urea, exhibiting linear (P < 0.01) and quadratic (P = 0.03) effects of fertilization rate. The 2-yr mean DM yield at the 100 kg N/ha fertilization rate was 3968 kg DM/ha, which was nearly twice that of the unfertilized (0 kg N/ha) check plots (2105 kg DM/ha). Yields of DM from LM and HM plots were 3029 and 3298 kg DM/ha, respectively, which differed from unfertilized check plots (3164 vs. 2105 kg DM/ha; P < 0.01), but differed only numerically from each other (P = 0.15). Collectively, total N uptake from plots fertilized with urea differed from unfertilized check plots (89 vs. 44 kg N/ha; P < 0.01), and also increased linearly (P < 0.01) with N fertilization rate from 44 kg N/ha for the unfertilized checks to 110 kg N/ha at the greatest urea fertilization rate. Uptake of N for plots receiving dairy slurry also differed from unfertilized check plots (77 vs. 44 kg N/ha; P < 0.01), but the HM and LM application rates only tended to differ (82 vs. 71 kg N/ha; P = 0.06). The apparent N recoveries from plots receiving urea differed from those receiving dairy slurry (83.0 vs. 23.1%; P < 0.01); however, apparent N recoveries for plots fertilized with urea only tended (P = 0.10) to decrease with N fertilization rate (range = 101.2 to 67.8%), and apparent N recoveries for LM and HM plots differed only numerically (27.2 vs. 19.0%; P = 0.65). When expressed as a percentage of the NH4-N applied within dairy slurry, apparent N recoveries for LM and HM also differed only numerically (66.7 vs. 46.9%; P = 0.22). Overall, fall-grown oat exhibited excellent ability to recover readily available soil-applied N during a short fall growing season, and potentially may limit N losses to the environment.