Biomass,nodulation and N2 fixing response by subclover and pink serradela to phosphorus fertilization |
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| Authors: | Ana Cristina Boucho Ramón Redondo Fátima Calouro Manuel Madeira |
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| Institution: | 1. Instituto Nacional de Investiga??o Agrária e Veterinária, Quinta do Marquês, Oeiras, Portugal;2. Laboratorio de Isótopos Estables, Universidad Autónoma de Madrid, Madrid, Spain;3. Centro de Estudos Florestais (CEF), Instituto Superior de Agronomia, Universidade de Lisboa, Lisboa, Portugal |
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| Abstract: | In Mediterranean areas, sustainable production of rainfed pastures is associated with plant species which withstand low soil fertility and variable annual drought, phosphorus (P) being the primary limiting nutrient for legume growth and N2 fixation. A study was undertaken under environmentally controlled conditions to compare the response of subclover and pink serradela to P supply using a moderately acid soil, very poor in available P, in terms of biomass, nodulation pattern, N2 fixation and P use efficiency. A P dose in the range of 30–60 kg P ha?1 is recommended as a starter for pastures under the present conditions. A higher P rate reduced the fixing nodule number and biomass, and the N2 fixation rate. Fixed N2 per unit of nodule P by pink serradela as monocrop was about 80% greater than the sole subclover, demonstrating its higher efficiency on the use of nodule P. Thus, pink serradela needs a lower P rate to produce the same amount of biomass per unit area as sole subclover. Long-term studies in field conditions, using these and other new pasture legume species are needed to consolidate the present findings. |
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| Keywords: | Mediterranean condition N2 fixation 15N technique pasture legumes phosphorus (P) partitioning in plant organs |
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