Effect of tree canopy and dolomitic limestone application on soil microorganisms and pasture quality in the Montado ecosystem

Abstract

The Montado, is an agro-silvo-pastoral ecosystem, explored in several extents. Its arboreal stratum is mainly composed by cork oak (Quercus suber) and holm oak (Q. rotundifolia) while the ground cover is formed by natural biodiverse pastures growing on poor soils and grazed by animals in an extensive regime. One of the major factors affecting the productivity of pastures in the Montado system is soil acidity (Serrano et al., 2020). The objective of this work is to evaluate the effect of tree canopy and dolomitic limestone application for soil acidity correction on soil microbial biomass carbon, arbuscular mycorrhiza colonisation rate, pasture floristic diversity and quality in the Montado ecosystem. Soil and root samples were collected in an experimental field (4ha) located in Mitra Farm in February 2022.In April we monitored the floristic composition of the pasture and measured its quality through the qualification of crude protein (CP) and fiber (neutral detergent fiber- NDF) content. The results showed that there was a positive and significant effect of the canopy on microbial carbon biomass and mycorrhizal colonization, and also significant differences on mycorrhizal colonization related to soil pH amendments, particularly under the tree canopy. Despite the lack of significant differences in CP and NDF, the average values for both parameters were higher under the canopy. Considering CP it was higher in the amended area, while NDF was lower in the same area. These results allowed us to perceive the effect of organic matter deposition associated to the tree canopy and soil acidity correction as key factors for microbial development (Cardoso & Andreote, 2016; Rodrigues et al., 2015) and pasture floristic diversity and quality in the Montado system, providing important information regarding the holistic management of this ecosystem.