Solubilización de fósforo por lupino (L. albus y L. angustifolius) en 4 suelos contrastantes en condiciones de invernáculo

A substantial amount of phosphorus (P) in soil is not readily available for plant uptake. Certain species may enhance P availability from poorly soluble P forms. The objectives of this greenhouse essay were as follows: i) to assess soil P availability (PBray1) by comparing two Lupine species, L. albus, and L. angustifolius, with a control crop of oats (Avena strigosa L.), ii) to evaluate accessible P levels and soil pH in four soil types with lupine to oat-containing soil and their baseline values. iii) to investigate how plant species and soil type affect shoot biomass, biological nitrogen fixation (BNF) rate, and potential P and nitrogen (N) contributions of two lupine species as precursor crops. Plants were cultivated in pots in four soils with varying textures, organic matter content, acidity and P availability. At harvest, various parameters were assessed, including shoot dry weight, plant P and N content, as well as lupine nitrogen fixation. Lupine soils showed PBray1 concentrations from 0.9 to 5.4 mg kg-1 (p < 0.0001), depending on species, sampling time, and soil type, when compared to soils containing oats. Interestingly, lupine-induced soil acidification did not fully explain this P increase. Manganese (Mn) concentration, an indirect measurement of organic acid exudation, was high in both lupine species' shoot biomass; however, these legumes had divergent responses to soil acidity and P availability. Nitrogen fixed quantity varied by Lupine species (105-240 mg pot-1) and soil type (60-240 mg pot-1). Lupinus albus had higher ability to mobilize non-labile P and give N through BNF, positioning it as a suitable crop for diversifying Uruguay's agricultural crop rotation systems.