title: Nitrogen removal and nitrate leaching for two perennial, sod-based forage systems receiving dairy effluent.
abstract: In northern Florida, year-round forage systems are used in dairy effluent sprayfields to reduce nitrate leaching. Our purpose was to quantify forage N removal and monitor nitrate N (NO3(-)-N) concentration below the rooting zone for two perennial, sod-based, triple-cropping systems over four 12-mo cycles (1996-2000). The soil is an excessively drained Kershaw sand (thermic, uncoated Typic Quartzip-samment). Effluent N rates were 500, 690, and 910 kg ha(-1) per cycle. Differences in N removal between a corn (Zea mays L.)-bermudagrass (Cynodon spp.)-rye (Secale cereale L.) system (CBR) and corn-perennial peanut (Arachis glabrata Benth.)-rye system (CPR) were primarily related to the performance of the perennial forages. Nitrogen removal of corn (125-170 kg ha(-1)) and rye (62-90 kg ha(-1)) was relatively stable between systems and among cycles. The greatest N removal was measured for CBR in the first cycle (408 kg ha(-1)), with the bermudagrass removing an average of 191 kg N ha(-1). In later cycles, N removal for bermudagrass declined because dry matter (DM) yield declined. Yield and N removal of perennial peanut increased over the four cycles. Nitrate N concentrations below the rooting zone were lower for CBR than CPR in the first two cycles, but differences were inconsistent in the latter two. The CBR system maintained low NO3(-)-N leaching in the first cycle when the bermudagrass was the most productive; however, it was not a sustainable system for long-term prevention of NO3(-)-N leaching due to declining bermudagrass yield in subsequent cycles. For CPR, effluent N rates > or = 500 kg ha(-1) yr(-1) have the potential to negatively affect ground water quality.
authors.affiliation: Agronomy Dep., Univ. of Florida, IFAS, Gainesville, FL 32611, USA. krw@mail.ifas.ufl.edu
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Woodard
authors.forename: Edwin C
authors.initials: EC
authors.lastname: French
authors.forename: Lewin A
authors.initials: LA
authors.lastname: Sweat
authors.forename: Donald A
authors.initials: DA
authors.lastname: Graetz
authors.forename: Lynn E
authors.initials: LE
authors.lastname: Sollenberger
authors.forename: Bisoondat
authors.initials: B
authors.lastname: Macoon
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Portier
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Rymph
authors.forename: Brett L
authors.initials: BL
authors.lastname: Wade
authors.forename: Gordon M
authors.initials: GM
authors.lastname: Prine
authors.forename: Harold H
authors.initials: HH
authors.lastname: Van Horn
mesh_terms: D001673:Biodegradation, Environmental; D031744:Cynodon / Q000737:chemistry / Q000254:growth & development; D003612:Dairying; D009566:Nitrates / Q000737:chemistry / Q000302:isolation & purification*; D009584:Nitrogen / Q000737:chemistry / Q000302:isolation & purification*; D018517:Plant Roots; D012434:Secale / Q000737:chemistry / Q000254:growth & development; D012989:Soil Pollutants / Q000302:isolation & purification*; D014873:Water Pollutants / Q000302:isolation & purification*; D003313:Zea mays / Q000737:chemistry / Q000254:growth & development
chemical_list: D009566:Nitrates; D012989:Soil Pollutants; D014873:Water Pollutants; D009584:Nitrogen