Abstract
The objective of this study was to evaluate the influence of agroforestry systems of different ages (AFS1: one-year old; AFS5: five-years old) on the biological attributes of soil; the following systems were used for comparison: a slash-and-burn (SBF) farming area, Caatinga which has been undergoing regeneration for 6 years (CaR6), and native Caatinga (NCa) in Brazil. Enzyme activity, abundance and composition of arbuscular mycorrhizal fungi (AMF), and production of glomalin-related soil proteins (GRSP) were evaluated at soil depths of 0–0.05 m. AMF species composition in the AFS was more similar to that in the NCa than in the SBF and CaR6 systems. In the rainy season, sporulation was most abundant in the AFS-1, CaR6, and SBF systems, whereas GRSP concentrations were highest in the AFS5 during the dry season. Acid phosphatase and arylsulfatase enzyme activity was lower in the AFS1 soils than in the NCa and SBF soils (rainy period), and levels of β-glucosidase and fluorescein diacetate hydrolysis in the AFS were equal to or higher than those in the NCa in the dry season but lower in the rainy season. AFS thus appear to promote the maintenance of soil biological quality, and may be more sustainable than SBF farming systems in the Brazilian Caatinga over the long term.
Highlights
Expansion of agriculture and livestock in Brazil can be traced back to the initiation of slashand-burn systems that are still common in northern and northeast Brazil, and which have considerable environmental effects
No significant differences in spore abundance were observed between the study areas in the dry season (Table 3), whereas in the rainy season, the most abundant sporulation was observed in the Agroforestry systems (AFS)-1, Caatinga vegetation under regeneration for 6 years (CaR6), and SBF sites (Table 3)
Averages followed by the same lowercase letter in a column are not statistically different by the Scott-Knott test at 5%; AFS1 and AFS5: Agroforestry systems with one and five years old, respectively; CaR6: Caatinga vegetation under regeneration for 6 years; native Caatinga (NCa): Native caatinga; SBF: Slash-and-burn farming with continuous cultivation of annual cycle monocultures; D: Dry period; R: rainy period
Summary
Expansion of agriculture and livestock in Brazil can be traced back to the initiation of slashand-burn systems that are still common in northern and northeast Brazil, and which have considerable environmental effects. In the municipality of Pedro II (Central-Northern region of the Piauí), an area dominated by the Caatinga biome, agriculture is almost exclusively based on the slash-and-burn approach. Agroforestry systems (AFS), in which agricultural crops are intercropped with forest species, have been shown to increase soil sustainability (CEZAR et al, 2015; DOLLINGER; JOSE, 2018). Together with the great biodiversity of species, promote a continuous supply of organic detritus that enhances soil organic matter content, which directly benefits soil physical, chemical, and biological attributes (YADAV et al, 2011; CEZAR et al, 2015; WEERASEKARA et al, 2016; DOLLINGER; JOSE, 2018; YENGWE et al, 2018)
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