PT - JOURNAL ARTICLE AU - D. M. Sullivan AU - C. G. Cogger AU - A. I. Bary AU - S. C. Fransen TI - Timing of dairy manure applications to perennial grass on well drained and poorly drained soils DP - 2000 Apr 01 TA - Journal of Soil and Water Conservation PG - 147--152 VI - 55 IP - 2 4099 - http://www.jswconline.org/content/55/2/147.short 4100 - http://www.jswconline.org/content/55/2/147.full AB - Timing of manure applications is a critical part of dairy farm plans because it affects water quality, crop production, and manure handling costs. We conducted a two year field study to provide information to farm planners on manure application timing for intensive grass production in the Pacific Northwest. We applied dairy manure slurry [340 kg total N ha-1yr−'; (300 lb N ac-1 yr−1)I to orchardgrass on well drained and poorly drained soils in western Washington, comparing early (February and May), mid-season (May through summer), and late (summer through fall, timing sequences for manure application. We also compared manure N rates ranging from 170 to 670 kg ba−l yf−1 (150 to 600 lb at−1 yr−1) for the mid-season application only. Forage yield, N uptake, apparent N recovery, and late-season soil nitrate-N were measured Cumulative apparent N recovery for manure N averaged 31 % and ranged from 24 to 38% over all treatments. The early and late manure sequences on the well drained soil had greater spring-harvest and cumulative yields than for the mid-season sequence. Timing effects were smaller and not statistically significant on the poorly drained soil. The effect of a manure application on grass production was greatest in the first harvest following application, and declined in subsequent harvests. Residual soil nitrate was less than 5 mg N kg−1 soil for all manure timing sequences applied at the 340 kg total N ha−1 yf1 (300 lb N at−1 yr−1) rate.