Accumulation of NO3 and NH4 in Reed Canarygrass1

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Abstract
Recent investigations have shown that reed canarygrass (Phalaris arundinacea L.) contains chemical compounds implicated with low palatability, reduced gains, and deaths in cattle. The purpose of this study was to investigate the effects of environmental variables on the accumulation of NO3 in reed canarygrass. An understanding of the response of this species to its environment will aid in the management and culture of reed canarygrass for production of livestock. Reed canarygrass clones were grown in sand‐filled pots in a growth room under the following controlled conditions: temperature, 15 and 30 C; irradiance, 4.2 and 42.0 W/m2; soil moisture, low medium, and saturated; fertilizer‐N, 0, 110, 220, and 440 kg/ha. The clones were cut from meadow sod where the soil, tentatively classified as Silvies series, was Fluventic and Cumulic Haplaquoll‐fine‐silty, mixed, mesic family. Herbage yields and accumulations of NH4‐N and NO3‐N at the end of three growing periods were evaluated. Increasing temperature from 15 to 30 C increased the rate of growth for plants receiving 42.0 W/m2. Yields were highest when plants were grown in saturated soil at 30 C with 42.0 W/m2 and 440 kg N/ha. Concentrations of NH4 and NO3 were highest in plants grown in unsaturated soil at 30 C with 4.2 W/m2 and 440 kg N/ha. When reed canarygrass was grown under these conditions, the NO3‐N concentration increased to 2.43%, 10 times the level (0.21%) considered potentially toxic to livestock.