ARS | Publication request: HERBAGE NITROGEN RECOVERY IN A MEADOW AND LOBLOLLY PINE ALLEY

Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: September 1, 2005
Publication Date: October 1, 2005
Citation: Burner, D.M., Mackown, C.T. 2005. Herbage nitrogen recovery in a meadow and loblolly pine alley [abstract]. Agronomy Society of America, Crop Science Society of America, Soil Science Society of America Meeting. Paper No. 2060.

Technical Abstract: Herbage in conventional pasture and agroforestry systems is managed for microclimate and spatial differences inherent to these systems, but managers have scarce data on which to base their decisions. Our objective was to measure herbage N fertilizer recovery at two sites, an unshaded meadow and a shaded alley in 10-yr-old loblolly pine [Pinus taeda (L.)]. The test was conducted on a Leadvale silt loam soil (fine-silty, siliceous, thermic Typic Fragiudult) near Booneville, Arkansas in 2002 and 2003, with tall fescue (Festuca arundinacea Schreb.) the predominant herbage species. Fertilizer N was broadcast as split-applications at six rates (100 kg/ha increments from 0 to 500 kg/ha/yr). The meadow and pine alleys had sufficient herbage yield for rotational livestock production. Cumulative herbage yield (CHY) in the meadow was much more responsive to added N than pine alley herbage, but average cumulative fertilizer N recoveries were only 38% and 12%, respectively. A shallow fragipan, low available soil P < 6 mg/kg, and depletion of soil water in July to September (both sites), and low solar irradiance (pine alley), were likely contributors to low fertilizer N recovery and herbage productivity. Because of poor herbage yield response and substantial accumulation of soil mineral N (62 to 237 kg/ha) in pine alleys fertilized with > 200 kg N ha/yr, only maintenance levels of fertilizer N (< 100 kg/ha) should be applied to similar sites. For these same reasons, yearly applications of fertilizer N > 300 kg/ha/yr are not recommended for meadows similar to the study site.