**Abstract**

Soil microbiome plays a significant role in soil's ecosystem for soils to be physically and biologically healthy. Soil health is fundamental for plant growth and crops productivity. In the introduction part, the roles and dynamics of the microbial community in soils, primarily in the cycle of soil organic carbon and CO2 release and absorption, are deliberated. Next, the impact of crop management practices and climate change on the soil carbon balance are described, as well as other issues related to soil degradation, such as unbalanced nutrient recycling and mineral weathering. In response to these issues, various approaches to soil regeneration have been developed in order to foster an efficient and active soil microbiome, thereby balancing the CO2 cycle and carbon sequestration in the soil ecosystem.

**Keywords:** soil microbiome, soil health, microbial CO2, CO2 sequestration, CO2 emission

## **1. Introduction**

Microbes are the most diverse organisms on the planet, both in terms of species and in terms of driving vital Earth system operations like the carbon cycle. The majority of this microbial biodiversity is found in soils [1]. According to Lederberg and McCray [2], the term microbiome refers to "the biological community of commensal, symbiotic, and pathogenic microbes that share human body space." This term grew in popularity as its definition evolved from organisms as taxonomic units (i.e., microbiota) to a collective genetic material throughout the years. However, as the term's popularity grew, there are various definitions of the term microbiome in the scientific literature.

Nowadays, most "microbiome" research focuses solely on bacteria, and the term "microbiome" is used interchangeably with "bacteria." As a result, new words for various microbial groupings have emerged, such as mycobiome, which refers to fungi, virome for the viruses, and eukaryome for the microbial eukaryotes [3]. Furthermore, the composition of microbiomes is known to change across time and space, making it difficult to find consistent and dependable sources of specific microbiomes [4].

The microbiome of the Earth accounts for almost half of all biomass on the globe [1]. Recent advances in DNA sequencing techniques have expanded our understanding of microbial biogeography, particularly among bacteria and fungi [5, 6]. Currently, the diverse composition of soil microbial community is widely known worldwide. The soil microbiome governs the biogeochemical cycling of macronutrients, micronutrients, and other elements that are vital for plants growth and animal life.

Microbiomes play an important role in a variety of biogeochemical processes, including the carbon and nitrogen cycles, which are necessary for ecosystems to function properly and sustainably. What functions do bacteria play in nutrient cycling and carbon sequestration to support the forests? It is critical to investigate the dynamics of microbial communities in order to comprehend their vital function in such a unique ecosystem. Acknowledging microbial ecology will aid in their management practices and protection, allowing peat accretion to continue and their carbon sequestration capacity to be protected [7].

The significance of soil microbiome activity in the soil ecosystem dynamics demands special consideration, as it promotes soil health and plant productivity [8]. Soil microbial activity is a possible indicator of soil quality as it responds quickly to changes in soil management and the environment. The carbon in crop residues moves *via* soil microbial biomass at least once, where it is moved from one C pool to another and eventually lost as carbon dioxide (CO2) [9]. It is critical to understand the factors that determine the richness of soil bacterial communities, as well as the organization of these communities, in order to forecast the responses of an ecosystem toward a specific environment. Changes in microbial populations or activity can occur prior to visible changes in soil physical and chemical properties, acting as an early indicator of soil improvement or degradation [10].

Soil characteristics such as pH, carbon, and nitrogen have been shown to influence soil microbial diversity and biogeography [11]. As a result, changes in the structure and behavior of soil microbial communities are more likely to be caused by differences in soil characteristics. Aside from that, soil organic matter (SOM) is critical to the function and quality of the soil. The high amount of SOM could increase nutrient availability while also improving the physical and biological features of the soil [12]. The level of soil organic carbon (SOC) is used to quantify the amount of SOM, and changes in SOC have an impact on the carbon (C) and nitrogen (N) cycles in terrestrial ecosystems [13]. The combined effects of chemical and biological features of the soil will affect the organic C and N fractions in organic compounds. As a result, understanding the processes that determine soil fertility, which is critical in farmland production systems, requires knowledge of soil microbial community dynamics and the factors that influence those dynamics in croplands.
