NITRATE ACCUMULATION IN ALTAI WILD RYEGRASS, RUSSIAN WILD RYEGRASS, AND CRESTED WHEATGRASS

The effects of three rates of N fertilizer and nine dates of initial harvest on the nitrate content of Altai wild ryegrass (Elymus angustus Trin.), Russian wild ryegrass (Elymus junceus Fisch.) and crested wheatgrass (Agropyron desertorum Fisch. Schult) were studied on irrigated land for 2 yr. The nitrate content of the forage of all three grasses increased with increasing rates of N fertilizer and varied with date of harvest. Toxic levels of nitrates (> 2000 ppm) were found in forage of all three grasses fertilized with 400 kg N/ha. Altai wild ryegrass accumulated toxic levels of nitrates more readily than Russian wild ryegrass and both ryegrasses accumulated toxic levels of nitrate more readily than crested wheatgrass. It is suggested that toxic levels of NO3-N can be expected in Altai and Russian wild ryegrass fertilized with 400 kg N/ha, but crested wheatgrass fertilized at similar rates should have toxic levels for only a short period, if at all.