Abstract
Agroforestry systems (AFS) are considered alternative land use options to help prevent soil degradation and improve soil microbial biomass and organic C status. However, it is unclear how different densities of babassu palm [Attalea speciosa (syn. Orbignya phalerata)], which is an important tree in Northeast Brazil, affect the soil microbial biomass. We investigated the soil microbial biomass C and activity under AFS with different densities of babassu palm associated with Brachiaria brizantha grass. Soil microbial biomass C (MBC), soil microbial biomass N (MBN), MBC:total organic C ratio, fluorescein diacetate hydrolysis and dehydrogenase activity showed highest values in plots with high density of babassu palm. On the other hand, the respiratory quotient (qCO2) was significantly greater in plots without babassu palm. Brachiaria brizantha in monoculture may promote C losses from the soil, but AFS with high density of babassu palm may increase the potential of soils to accumulate C.Keywords: Enzyme activity, tropical soil, babassu palm, silvopastoral system, soil quality.DOI: 10.17138/TGFT(3)41-48
Highlights
The babassu palm [Attalea speciosa Mart. ex Spreng
Similar to soil microbial biomass, the qMIC was highest in HD and lowest in MC plots (P
The results suggest that the density of babassu palm in Agroforestry systems (AFS) affects soil microbial biomass C
Summary
The babassu palm [Attalea speciosa Mart. ex Spreng. (syn. Orbignya phalerata Mart.)] occurs widely in Brazil, Colombia, Bolivia and Mexico and its fruits are a source of lauric oil, having both edible and industrial uses. Over 80% of babassu palms found in Brazil are AFS is an alternative land use system to help prevent land degradation, by allowing continued use of land to www.tropicalgrasslands.info produce crops or pastures in association with trees on a sustainable basis (Araújo et al 2012). Such systems involve the combination of at least one woody-perennial species with a crop or pasture, which results in ecological and economic interactions between the two components (Palma et al 2007). Several authors have reported that soil microbial biomass is greater in an AFS, owing to the effects of trees and organic matter input and differences in the quality and quantity of litter and root exudates (Gómez et al 2000; Myers et al 2001; Mungai et al 2005; Sørensen and Sessitsch 2007)
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