Short-term Effect of Eucalyptus Wood-based Compost on Biological Fertility of Soils under Avocado Plantations

ABSTRACT

This study investigated the effects of a eucalyptus-based compost on soil microbial community and enzyme activities of soils under avocado plantations in Limpopo, South Africa. It was hypothesized that compost application rate and time-post application would determine the abundance of biological organisms and enzyme activities. Experiments were conducted on 8-year-old ‘Hass’ avocado orchards. A repeated measures design with four compost treatments (0, 5, 10, and 15 ton ha⁻¹ year⁻¹), replicated three times was used. Thermophilic compost was prepared from locally sourced Eucalyptus wood chips (40%) and sawdust (20%), chicken manure (20%), and cattle manure (20%) stock feed. Soil samples were collected at three-month intervals for a period of nine months and analyzed for soil biota and enzyme activities. The results showed that compost application led to improved soil microbial counts and the effects were compost application rate and time dependent. The highest microbial counts were realized at 15 tons ha⁻¹ and increased with time post compost application. Phosphatase, β-glucosidase, and urease were slightly increased at 10 and 15 tons ha⁻¹ whereas fluorescein di-acetate was not affected by compost application rates. Compost application rates did not show a consistent effect on soil enzymes activities across sites and time.

KEYWORDS:

• Compost application rate
• enzyme activity
• soil fertility
• total bacteria
• total fungi

Acknowledgments

The authors appreciate with great thanks, the National Research Fund (NRF) and ZZ2 Bertie van Zyl (Pty) Ltd for funding this study.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Additional information

Notes on contributors

Alen Manyevere

M.M.P designed and carried out the research in consultation with A.M and Z.M.G.; E.D, A.M and M.M.P analyzed the data. All the authors contributed equally to the writing of the manuscript.