Growing Triticum aestivum Landraces in Rotation with Lupinus albus and Fallow Reduces Soil Depletion and Minimises the Use of Chemical Fertilisers

In north-western Spain, the cultivation of wheat landraces represents the pillar of quality Galician bread; today, a minimum of 25% Galician flour is required to produce bread under the auspices of the Protected Geographical Indication “Pan Galego”. The main objective of this study was to evaluate the effect of the rotation of two wheat landraces—‘Carral’ and ‘Caaveiro’—with lupin (sweet Lupinus albus ), together with a fallow period, on crop yield and quality, as well as the environmental benefits of rotations over conventional monoculture systems. After the different agricultural activities, twelve agronomic parameters were analysed at the end of the third year. For the environmental analysis, the Life Cycle Assessment methodology was applied. The results showed a positive influence of rotation systems on wheat yield and quality parameters, reporting higher specific weight and lower impurities compared to monoculture. No significant differences were observed between wheat rotation and monoculture in other parameters related to baking quality, such as protein, wet gluten, baking strength (W), elasticity (L), tenacity (P), and swelling (G). However, soil quality influenced wheat quality independently of rotation, and higher organic matter and lower phosphorus produced higher W and P, respectively. Moreover, rotation had a positive effect on yield, up to 62% when fallow preceded wheat, and in reducing diseases, pests, and weeds. Finally, in terms of environmental performance, the best results were identified when lupin preceded wheat due to lower fertiliser application. In this regard, the worst profiles corresponded to the scenarios based on monoculture for both wheat landraces.