Bacterial abundance of cacao agroforestry, cacao monoculture and secondary forest land uses in north Luwu, South Sulawesi

Abstract

Expanding the agricultural sector in North Luwu influences land use modification to enhance plantation output. Continuous land use and clearance can jeopardize the survival of native land vegetation, altering C and N cycles, community composition, population, and soil microbial activity. Microorganisms are essential for maintaining the health and quality of the soil. The abundance of soil microorganisms significantly impacts ecosystem function, so it can help boost agricultural output. This demonstrates that data on the abundance and diversity of soil microorganisms can be used to determine soil fertility. However, more information is needed about the diversity of soil microbes in North Luwu. This study seeks to determine the abundance of soil microorganisms, particularly for various land uses. Random soil samples were collected from cacao monoculture, cacao agroforestry, and secondary forest. The C: N ratio and the total number of microorganisms were then measured in the collected soil samples. Cacao agroforestry with the highest C: N ratio had 1.8 x 108 CFU/g of total soil bacterial, the highest bacterial abundance among the three land covers, followed by secondary forest and cacao monoculture with the lowest C: N ratio and lowest bacterial abundance 2 x 107 CFU/g. These results indicated that the soil C: N ratio influences the bacterial abundance of various land uses. The highest abundance of nitrate-fixing bacteria was found in secondary forests and the lowest in cacao agroforestry, even though the %N indicated by both was the same.