NITROGEN RECOVERY BY ORCHARDGRASS FROM DAIRY MANURE APPLIED WITH OR WITHOUT FERTILIZER NITROGEN

With increasing manure production per unit cropland available for its disposal, greater recovery and recycling of manure nitrogen (N) throug h crop uptake is needed on dairy farms to minimize environmental probl ems. This study was conducted in 1990 and 1991 on a sandy loam soil wi th the objective of quantifying forage yield and N recovery by orchard grass (Dactylis glomerata L.), in response to dairy manure applied in spring with or without fertilizer N. Manure N, either as liquid or as solid with bedding, was surface applied annually to supply 150 kg tota l N/ha/yr with four rates of fertilizer N (0, 75, 150, and 300 kg N/ha in 1990 and 0, 150, 300, and 600 kg N/ha in 199 1) factorially superi mposed over the manure treatments. Averaged over years, orchardgrass r ecovered 40% of the liquid manure N and 26% of the solid manure N appl ied each year. On an annual basis, the crop recovered 430 kg soil N/ha /yr from plots receiving liquid manure in combination with 600 kg fert ilizer N/ha. This study demonstrates that intensively managed orchardg rass has the potential to absorb large quantities of manure N.