Temporal variation in nitrogen concentration of above ground perennial ryegrass applied different nitrogen fertiliser rates |
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| Affiliation: | 1. Department of Environmental Chemistry, University of Kassel, Nordbahnhofstr. 1a, 37213 Witzenhausen, Germany;2. Institute of Crop Science and Plant Breeding, Grass and Forage Science/Organic Agriculture, Christian-Albrechts-University of Kiel, Hermann-Rodewald-Str. 9, 24118 Kiel, Germany;3. Department of Soil Biology and Plant Nutrition, University of Kassel, Nordbahnhofstr. 1a, 37213 Witzenhausen, Germany;1. Instituto Nacional de Tecnología Agropecuaria (INTA), Estación Experimental Agropecuaria Balcarce, CC 276, 7620 Balcarce, Buenos Aires, Argentina;2. Centro de Investigación Veterinaria Tandil, (CIVETAN), Argentina;3. CSIRO, PO Box 102, Toowoomba, QLD 4350, Australia;4. Facultad de Ciencias Veterinarias, UNICEN, Campus Universitario, B7000, Tandil, Buenos Aires, Argentina;5. Modasur (Regional network for agricultural modelling research), Argentina;1. Leibniz Centre for Agricultural Landscape Research (ZALF), Institute of Landscape System Analysis, Eberswalder Straße 84, 15374 Müncheberg, Germany;2. Humboldt-Universität zu Berlin, Faculty of Life Science, Institute of Agriculture and Horticulture, Division of Soil Science and Site Science, Albrecht-Thaer Weg 2, 14195 Berlin, Germany;1. Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton SO14 3ZH, United Kingdom;2. GEOMAR Helmholtz Centre for Ocean Research, 24148 Kiel, Germany |
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| Abstract: | Perennial ryegrass (Lolium perenne L.) was grown for seed in field trials in order to investigate the temporal variation in plant nitrogen (N) concentration during ontogeny. Crops were sown in three successive years and grown with five N fertiliser rates applied in the autumn and in the spring (autumn–spring): 0–0, 0–50, 0–100, 30–120 or 60–140 kg N ha−1. Within each N fertiliser rate, N concentration in the plants increased from the initiation of spring growth and reached a maximum of 4.8% at 450–500 growing degree-days (GDD) after which it decreased to 0.8% at 1150–1200 GDD. This pattern of plant N concentration was consistently low at each N fertiliser rate and between years whereas the variation in plant N concentration within each year was high as a result of the different N fertiliser rates. Nitrogen fertiliser rate up to 150 kg N ha−1 increased the seed yields.During spring growth 89% of the variation in plant N concentration could be explained by a non-linear function of GDD. Maximum variation occurred at 480 GDD, with a 95% confidence interval between 428 GDD and 540 GDD. Plant N concentrations measured at 424 GDD in 1998, 447 GDD in 1997, and 497 GDD in 1996, and the resulting correlation coefficients (r2) between N concentration and seed yield were 0.81, 0.71 and 0.92, respectively.It is concluded that the variation in plant N concentration during ontogeny in perennial ryegrass is related to different N fertiliser rates and that the greatest variation in plant N concentration was in the period from 428 GDD to 540 GDD. |
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