Effect of Light on Yield, Nutritive Value of Brachiaria decumbens, and Soil Properties in Silvopastoral Systems, Peruvian Amazon

Silvopastoral systems, integrating trees, forages, and livestock, are recognized as a sustainable approach to livestock production. This study evaluated the effect of shade vs. open-field conditions on the yield and nutritive value of Brachiaria decumbens in three systems—Inga edulis (guaba), Eucalyptus torrelliana (eucalyptus), and Cedrelinga cateniformis (tornillo)—in the Peruvian Amazon. A 3 × 2 factorial design with three replicates was used to analyze forage production (mass and mass by harvest), quality (NDF, protein, digestibility, metabolizable energy), and soil variables (bulk density, pH, organic matter, moisture, porosity, etc.). Most interactions were non-significant, except forage mass by harvest (FMH, p = 0.0328). B. decumbens in the guaba system under shade had the highest FMH (1406 kg DM ha−1), while the tornillo system showed elevated protein (10.63%). Protein was significantly higher under shade (9.55%) than in open field. Eucalyptus increased neutral detergent fiber (69.72%), whereas guaba provided the greatest metabolizable energy (8.08 MJ kg−1 DM). Soil analyses revealed improved moisture and CEC under guaba, while tornillo boosted soil phosphorus. Principal component analysis confirmed these associations (82.3% variance). B. decumbens grown under the shade of guaba or tornillo appears to enhance forage productivity and soil fertility, representing a promising strategy for sustainable tropical livestock management.