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During drought years, stream flow is often insufficient to irrigate normally flooded native meadows. Herbage production of the meadow is reduced, haying operations are suspended, and the available forage is grazed by cattle. Fertilization of meadows in eastern Oregon is done in the late fall or early spring before the availability of irrigation water for the following growing season is known. This study was initiated in 1977, following a severe winter drought, to determine the effect of fertilizing meadows in a dry year. Urea fertilizer was applied at 13 rates (0 to 745 kg N/ha). Maximum forage production of 1,000 kg/ha occurred about midJuly for the check treatment. Production was not increased at fertilizer rates of 0 to 50 kg N/ha, but were increased up to 1,600 kg at fertilizer rates of 95 to 745 kg N/ha. Crude protein concentrations in the forage were similar to those measured in years of normal rainfall. Herbage N03-N levels were considered nontoxic at fertilizer rates less than 540 kg N/ha. It appears that during years of low precipitation, with customary rates of fertilization (90-110 kg N/ha), forage production will be increased slightly, forage quality will be about normal, and the danger of nitrate poisoning will be nil. The vegetation community of seasonally flooded meadows in eastern Oregon evolved concomittently with extended annual periods of flooding. Meadow plants generally require that the soil be saturated or shallowly ponded most of the growing season. Forage yields are strongly influenced by the seasonal period and duration of flooding. Rumburg and Sawyer (1965) determined that yields increased as length of flooding increased except when the water depth was greater than 18 cm. Forage yields were influenced more by the length than the period of flooding. An excessive length of flooding increased rushes and sedges and decreased yields of grasses. During drought years such as 1977, stream flow may be sufficient to irrigate only a small part of the meadowland in eastern Oregon. Herbage production, for the most part, is too low to justify the expense of haying operations, and the limited amount of forage produced is grazed by cattle as they are removed from range when that source of forage is depleted. Although not specifically documented, it has been suspected that forage produced on meadows is further reduced by applying fertilizer, but the crude protein concentration may be higher than when it is produced under normal flooded conditions. The purpose of this study was to determine the effects’of applying fertilizer to meadowlands on the yield, crude protein, and potential nitrate danger to livestock of forage produced in a dry year. Methods and Procedure Urea (46% N) was applied April 29, 1977, to native meadowAuthor is range scientist, USDA, Agr. Res. Serv., Crops Research Lab., Utah State University, Logan 84322, formerly at Oregon State University, Squaw Butte, Agr. Exn. Sta.. Bums 97720. Thisarticle representscooperative investigationsofthe USDA, Agr. Res. Serv.,and the Agr. Exp. Sta.. Oregon State University. Tech. Pap. No. 5465 of the latter. Manuscript received October 24, 1980. lands of the Squaw Butte Experiment Station, located about 10 km southeast of Burns, Ore. Fertilizer at 13 rates, ranging from 0 to 745 kg N/ha, was applied in strips 10 m wide using a tractormounted broadcaster. The design provided 10 replicated plots of each treatment. The study site, characterized as high cold desert, averages about 30 cm precipitation annually, of which 6 cm occurs during the growing season. The soil, tentatively classified as Silvies seriesFluventic and Cumulic Haplaquolls, was developed from lacustrine sediments. The vegetation was typical of wild flood meadow. Dominant plant species were Baltic rush (Juncus balticus Willd.), slender sedge (Carex praegracilis W. Boott), Nebraska sedge (Carex nebraskensis Dewey) with varying amounts of Nevada bluegrass (Poa nevadensis Vasey ex Scribn.), and beardless wildrye (Elymus triticoides Buck.). Average production of the native meadow is about 1.7 metric ton/ha. At weekly intervals, May-August 12, several whole plant samples of the meadow forage were taken randomly from each plot. These samples were later analyzed for crude protein. On June 16, July 15, and August 12, two m* samples were harvested near the center of each plot. Harvests taken subsequent to June 16 were collected from areas not harvested previously. Samples were dried at 65°C for 48 hours, weighed, ground, and analyzed for total nitrogen (crude protein) and nitrate-N. Analyses for crude protein were by the standard Kjeldahl method, and analyses for NOs-N followed the micro-Kjedahl method of Bremner and Edwards (1965) as modified for plant samples by the Soil Testing Laboratory of Oregon State University. Soil samples to 15cm depths were taken from the 0 to 385 kg N/ha treatments at about 2-week intervals, May 13-August 15. These were dried at loo0 C for 24 hours to determine soil moisture percentage. Air-dried samples were analyzed for NOs and N&. Analyses followed the micro-Kjedahl methods of Bremner and Edwards (1965). Results and Discussion Previous to applying fertilizer, southeastern Oregon had experienced one of its most severe winter droughts. From October 1, 1976, to May 1, 1977, only 2.5 cm of precipitation had occurred (Gomm 1979). Subsequent precipitation was 5.1 cm in May, 1.5 cm in June, and 0.5 cm in July. The May precipitation was not sufficient to provide flood water to the meadow but benefited early growth. Plant growth commenced with the spring moisture; however, considerable variability occurred within plots due to microrelief and uneven distribution of soil moisture. Soil Analyses As the season progressed, the soil moisture generally declined from 67% on May I3 to 42% on June 2 1 and 25% on August 15 without response to fertilizer treatments. Soil N levels were highest as NH4 early in the season, and the NH4 levels generally increased as the fertilizer rates increased (Fig. 1). By the end of May (I month after application), there were no significant differences among rates less than 95 kg N/ha. At rates JOURNAL OF RANGE MANAGEMENT 35(4), July 1982 477

Meadow Forage Production as Influenced by Fertilization in a Dry Year