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Biomass, nodulation and N₂ fixing response by subclover and pink serradela to phosphorus fertilization

Boucho, Ana Cristina, Carranca, Corina, Redondo, Ramón, Calouro, Fátima, Madeira, Manuel
Archiv für Acker- und Pflanzenbau und Bodenkunde 2019 v.65 no.10 pp. 1431-1445
acid soils, biomass, drought, fertilizer application, legumes, nitrogen, nitrogen fixation, nodulation, nutrient use efficiency, pastures, phosphorus, phosphorus fertilizers, soil fertility, Mediterranean region
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.