Nitrogen Removal by Orchardgrass and Smooth Bromegrass and Residual Soil Nitrate

Although cool-season grasses increase DM yield at high N rates, N recovery (kg plant N kg 1 N applied) Nitrogen removal by cool-season grasses may aid in capturing exgenerally declines as N rate increases. Ramage et al. cess N from animal confinement operations or phytoremediation. (1958) reported fertilizer N recovery of 0.59 and 0.59 kg Limited information exists on the N dynamics of these grasses near the asymptote of the N response curve. The objectives of this study kg 1 in orchardgrass and 0.61 and 0.59 kg kg 1 in reed were to evaluate N removal, residual soil NO3–N, and apparent N canarygrass (Phalaris arundinacea L.) at N rates of 56 recovery in orchardgrass (Dactylis glomerata L.) and smooth bromeand 448 kg N ha 1, after accounting for soil N. George grass (Bromus inermis Leyss.) at annual N rates of 224, 448, and 672 et al. (1973) reported maximum fertilizer N recovery of kg ha 1. Species harvest interactions were observed in both years, 0.49 kg kg 1 in a dry year, while recovery values were but no species N rate interactions occurred. Orchardgrass removed 0.67 in orchardgrass and 0.72 kg kg 1 in smooth brome352 and 505 kg N ha 1 yr 1 at the 448 N rate compared with 207 and grass in a year with more normal precipitation at annual 371 in smooth bromegrass in 1999 and 2000, respectively. In a dry N inputs of 168 kg N ha 1. These values were somewhat year, orchardgrass (r 2 0.41) and smooth bromegrass (r 2 0.31) higher than those reported by Zemenchik and Albrecht exhibited linear N uptake. In a year with adequate rainfall, a quadratic (2002) in a three-cut harvest system under Wisconsin relationship was observed for orchardgrass (R2 0.92), while smooth bromegrass had linear uptake (r 2 0.66). Greater N removal was conditions, where apparent N recovery ranged from 0.32 observed in orchardgrass partly because of superior fall growth, when to 0.50 kg kg 1 in orchardgrass and 0.17 to 0.44 kg kg 1 99 and 82 kg N ha 1 were removed in 1999 and 2000 at the 448 N in smooth bromegrass at N rates ranging from 0 to 336 rate compared with 23 and 15 kg N ha 1 in smooth bromegrass. These kg N ha 1 applied in split applications. removal rates accounted for 28 and 16% of the seasonal total in 1999 Measuring residual soil NO3–N after a fall growth and 2000 in orchardgrass and 11 and 4% in smooth bromegrass. cycle provides some indication of soil N available for Orchardgrass N removal exceeded smooth bromegrass in a three-cut leaching after plant growth cessation. Vetsch et al. system, and this difference was enhanced by utilizing the fall growth (1999) found minimal residual soil NO3–N under reed period to capture residual soil N. canarygrass in November at N rates up to 449 and 393 kg ha 1 in the top 1.5 m of the soil profile in a wet and dry year, respectively. They concluded that reed N removal of cool-season grasses is an imcanarygrass can serve as a sink that can assimilate excess portant criterion for species selection in situations fertilizer N up to 112 kg ha 1. Kowalenko and Bittman where excess soil N availability occurs. Confinement (2000) found 1, 23, and 10 mg N kg 1 in the top 60 cm animal-production operations with land constraints for of the soil profile in the fall after fourth cut in three manure distribution can utilize cool-season grasses to consecutive years in plots of predominately orchardgrass capture large quantities of N. The resulting forage could that received 200 kg N ha 1 in early spring followed by be sold to niche markets such as the equine industry 100 kg N ha 1 after the first and second cuttings. Limited because equine can tolerate up to 10 times the level residual soil NO3–N data are available in the literature of plant tissue NO3–N concentration that is toxic to at N rates that exceed annual applications greater than ruminants (Lewis, 1995). 400 kg N ha 1 in orchardgrass and smooth bromegrass. Cool-season forages may also be utilized for remediaThe objectives of this study were to measure N removal, tion of fertilizer spill sites. Russelle et al. (2001) found residual soil NO3–N, and apparent N recovery of mono‘Ineffective Agate’ alfalfa (Medicago sativa L.) hay respecific cultures of orchardgrass and smooth bromegrass moved 972 kg N ha 1 over a 3-yr period at a fertilizer at optimum and very high N rates. N spill site in North Dakota. Cherney et al. (2002) reported N uptake in orchardgrass and tall fescue of 139 MATERIALS AND METHODS and 157 kg N ha 1 yr 1 with an average fertilizer and manure N input of 249 kg ha 1 from 1994 through 1997. A 2-yr field study was established in the fall of 1998 on a Quakertown silt loam (fine-loamy, mixed, mesic Typic HapluThese uptake levels are about half of those reported by dults) at the Rutgers University Snyder Research and ExtenRusselle et al. (2001) for alfalfa, but also represent N sion Farm near Pittstown, NJ (40 30 N, 75 00 W). ‘Pennlate’ uptake at N rates that do not maximize yield. George orchardgrass and ‘Saratoga’ smooth bromegrass were seeded et al. (1973) reported that orchardgrass and smooth as main plots at 13 kg seed ha 1 with an oat (Avena sativa L.) bromegrass increased dry matter (DM) yields up to 672 cover crop (54 kg seed ha ) on 11 September. A commercial kg N ha 1. grain drill was used in 6117-m plots in a randomized complete block with a split-plot arrangement of treatments and four replications. J.W. Singer, USDA-ARS, National Soil Tilth Laboratory, Ames, IA Main plots were forage species. Subplots consisted of three 50011-4420; K.J. Moore, Dep. of Agronomy, Iowa State Univ., Ames, N rates, 224, 448, and 672 kg N ha 1 yr . These rates were IA 50011-1010. *Corresponding author ([email protected]). achieved by supplying either 112, 224, or 336 kg N ha 1 in the spring at green-up followed by 56, 112, or 168 kg N ha , Published in Crop Sci. 43:1420–1426 (2003).