Long-term Implementation of a Silvopastoral System Enhances Soil P Availability and Bacterial Diversity

A silvopastoral system (SPS) is defined as a type of agroforestry system wherein grasses combine with legumes, shrubs, and trees for animal nutrition. Its use, as an alternative to grasslands, represents a promising strategy to increase livestock industry sustainability. In this work, we explored the long-term impact of the implementation of a SPS on soil P nutrition, soil phosphomonoesterase activity, and microbial diversity. For this, we harnessed a 9-year-old SPS consisting of a tree (Alnus acuminata), two shrubs (Sambucus nigra and Sambucus peruviana), and a grass (Cenchrus clandestinrr44us), as well as a nearby pasture consisting solely of the C. clandestinus grass, which we used for comparison. We collected samples during the rainy and dry seasons. The implementation of the SPS enhanced the availability of labile soil P, compared to the nearby pasture; this increase concomitantly occurred with a decrease of moderately-labile P. We also noted that labile Pi and Po significantly correlated with alkaline phosphomonoesterase activity, suggesting a potential role of this soil enzymatic activity on P availability within the SPS. There was an increase of diversity and a shift in the bacterial community in the SPS compared to the pasture. Within the SPS, the tree and shrub strips had the largest influence on soil P availability and phospho-monesterase activity. Altogether, this study documents the benefits of the implementation of a SPS on soil P availability and bacterial diversity.