Submitted to: Journal of Production Agriculture
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/15/1999
Publication Date: N/A
Citation: Interpretive Summary: To reduce the impact of weather, different soils, and pest outbreaks on profitability, livestock producers who depend on grazing, hay, or silage need to have alternative forage crops to plant on their farms. They also need to know how to manage these forages to produce enough high quality forage for their animals. Reed canarygrass is a forage that has a poor reputation, in part because older varieties were not appetizing to livestock and reduced milk and meat production. Newer varieties of reed canarygrass overcome this problem. In this research, we determined how one of these new varieties responded to nitrogen fertilizer. Our field study showed that both forage yield and protein content could be increased with optimum nitrogen fertilizer applications. At the same time, reed canarygrass was able to use the added nitrogen quite efficiently and minimize the chance that nitrogen fertilizer might move into ground water. Our research also demonstrated that both timing and amount of nitrogen fertilizer affected the buildup of nitrate in the grass forage. High nitrate in forage is potentially harmful, and our results will help farmers choose fertilizer management schemes that reduce risk to their livestock. These results add to the database of best management practices for production of an abundant and healthful food supply, while providing excellent environmental protection.
Technical Abstract: Reed canarygrass (Phalaris arundinacea L.) is a high-yielding, cool-season forage that responds to high rates of N. Forage growers need additional information on N management strategies for improving production without inducing negative consequences. Three, 1-yr studies were conducted from 1992-1994 on a Webster clay loam (fine-loamy, mixed, superactive, mesic Typic Endoaquolls) in southern Minnesota to determine the optimum rate of and the effect of split applications of N on forage yield, crude protein, forage NO3N concentration, and residual soil NO3. Ammonium nitrate was topdressed to established stands of reed canarygrass at rates from 0 to 600 lb N/acre. Single, early-season (April or May) applications were compared to split applications (early-season + after 1st cutting). Total DM production was optimized by N rates totaling 250 to 300 lb/acre in 1992 and 1993 and by only 150 to 200 lb/acre in the lower yielding year, 1994. Split tapplications of N did not further improve DM yields above those obtained with the optimum N rate applied as a single, early-season treatment. Forage NO3-N concentrations ranged from 40 to 7230 mg/kg (<3000 is considered dangerous) and were greatly influenced by rate and time of N application and growing season conditions. Residual soil NO3 did not accumulate until the agronomic optimum N rate was exceeded by 100 lb/acre. Results from this study indicate that DM yield and crude protein percentage of reed canarygrass can be optimized with high rates of N applied early in the season, but undesirably high concentrations of NO3-N in the forage should be expected when optimum rates of fertilizer N are exceeded.