RT Journal Article
SR Electronic
T1 Runoff nutrient losses from tall fescue pastures varying in endophyte association, fertilization, and harvest management
JF Journal of Soil and Water Conservation
FD Soil and Water Conservation Society
SP 25
OP 38
DO 10.2489/jswc.2021.00164
VO 76
IS 1
A1 D.M. Endale
A1 H.H. Schomberg
A1 A.J. Franzluebbers
A1 D.S. Seman
A1 D.H. Franklin
A1 J.A. Stuedemann
YR 2021
UL http://www.jswconline.org/content/76/1/25.abstract
AB Tall fescue (Lolium arundinaceum [Schreb.] S.J. Darbysh.) is a widely adopted cool-season perennial forage in the southeastern United States. Historically, tall fescue contained a symbiotic fungal endophyte, Epichloë coenophiala, that produced an ergot alkaloid toxic to livestock. New fescue biotypes have been developed that are endophyte free or include endophytes that produce low-toxicity alkaloids. Ecological implications of these biotypes are not fully understood. We evaluated nutrient runoff quality for three tall fescue biotypes (common, high alkaloid endophyte [wild]; low alkaloid endophyte [novel]; and endophyte free [free]) under two fertilizer sources (broiler litter [BL] and inorganic fertilizer) in grazed systems and a hayed system with inorganic fertilization of endophyte free fescue. The seven treatments were replicated twice on 1 ha paddocks near Watkinsville, Georgia. Grazed paddocks were stocked in September each year with weaned Angus (Bos taurus) heifers (2002 to 2007) and steers (2008 to 2009) at rates of ~3 to 6 head paddock–1 adjusted every 28 days to maintain 1 to 3 Mg ha–1 of available forage. Weather conditions varied from very dry to very wet and allowed 15 grazing periods (50 to 198 days). Tall fescue with novel-endophyte association had lower or equal runoff concentrations and loads for inorganic nitrogen (N), total N (TN), ortho-phosphorus (ortho-P), and total P (TP) than fescue with wild- or free-endophyte association (fescue treatment mean concentrations [mg L–1]: <0.8 inorganic N, <4.0 TN, <3.5 ortho-P and TP; mean loads [kg ha–1]: <0.08 inorganic N, <0.40 TN, <0.30 ortho-P and TP; all original untransformed data). This indicates increased adoption of novel-endophyte fescue, as previously recommended, presents no additional risk for nutrient losses regardless of fertilization source. Weather variability had impact on assessed variables. Mean total runoff across all paddocks during above average (27.2%) and average (20.6%) monthly rainfall periods were 15.2- and 1.9-fold greater than that from the below average (52.2%) monthly rainfall period. Nutrient loads also were greater: 3.4-fold (TP) to 14.6-fold (ammonium-N). Pollutant loads in the upper quartile were several fold greater than those from the rest of the data. The presence of cattle increased ortho-P load up to 3-fold compared with periods with no cattle.