Effects of nitrogen fertilization on soil nutrient concentration and phosphatase activity and forage nutrient uptake from a grazed pasture system.
Over a 3-year period, the effect of differing N-application regimes on soil extractable-P concentration, soil phosphatase activity, and forage P uptake in a P-enriched grazed-pasture system was investigated. In the fall of each year, six 0.28-ha plots were overseeded with triticale ( × Triticosecale rimpaui Wittm.) and crimson clover (Trifolium incarnatum) into a tall fescue (Lolium arundinacea)/bermudagrass (Cynodon dactylon) sod and assigned to 1 of 3 N-fertilizer treatments (n = 2): 100% of N recommendation in a split application (100N), 50% in a single application (50N), and 0% of N recommendation (0N) for triticale. Cattle commenced grazing the following spring and grazed until May. In the summer, plots were overseeded with cowpea (Vigna unguiculata), fertilized at the same rates by reference to N recommendations for bermudagrass, and grazed by cattle until September. There were no effects of N fertilization on soil phosphatase activity, electrical conductivity, or concentrations of water-soluble P. Concentrations of extractable P decreased in plots receiving 50N, but increasing N fertilization to 100N resulted in no further reduction in extractable P. Forage biomass, foliar P concentrations, and forage P mass were not affected by N fertilization rates at the plant-community level, but responses were observed within individual forage species. Results are interpreted to mean that N fertilization at 50% of the agronomic recommendation for the grass component can increase forage P mass of specific forages and decrease soil extractable P, thus providing opportunity for decreasing P losses from grazed pasture.
209 Upchurch Hall, Department of Animal Sciences, Auburn University, Auburn 36849, AL, USA. Electronic address: sdillard@uga.edu.
Sandra Leanne
SL
Dillard
201 Funchess Hall, Department of Crop, Soil and Environmental Sciences, Auburn University, Auburn 36849, AL, USA. Electronic address: woodcha@tigermail.auburn.edu.
Charles Wesley
CW
Wood
201 Funchess Hall, Department of Crop, Soil and Environmental Sciences, Auburn University, Auburn 36849, AL, USA. Electronic address: woodbre@tigermail.auburn.edu.
Brenda Hall
BH
Wood
201 Funchess Hall, Department of Crop, Soil and Environmental Sciences, Auburn University, Auburn 36849, AL, USA. Electronic address: fengyuc@tigermail.auburn.edu.
Yucheng
Y
Feng
209 Upchurch Hall, Department of Animal Sciences, Auburn University, Auburn 36849, AL, USA. Electronic address: owslewf@tigermail.auburn.edu.
Walter Frank
WF
Owsley
209 Upchurch Hall, Department of Animal Sciences, Auburn University, Auburn 36849, AL, USA. Electronic address: muntirb@tigermail.auburn.edu.
Russell Brian
RB
Muntifering
D000821:Animal Feed / Q000032:analysis*; D000822:Animal Husbandry; D000818:Animals; D002417:Cattle; D031744:Cynodon / Q000378:metabolism; D002523:Edible Grain / Q000378:metabolism; D005260:Female; D005308:Fertilizers; D031751:Festuca / Q000378:metabolism; D008297:Male; D029902:Medicago / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D006109:Poaceae / Q000378:metabolism; D012621:Seasons; D012987:Soil / Q000737:chemistry*; D029921:Trifolium / Q000378:metabolism
D005308:Fertilizers; D012987:Soil; D010744:Phosphoric Monoester Hydrolases
Beef cattle; Forage; Nitrogen; Phosphorus