## 1 Introduction  
Microorganisms are among the most biologically active components of soil ecosystems and play a pivotal role in maintaining ecosystem functionality [1, 2, 3, 4]. As the main decomposers in farmland ecosystems, they are closely involved in key soil processes, including organic matter decomposition, nutrient cycling, and humus formation [5, 3]. Currently, soil microbial community diversity is widely recognized as a critical indicator of soil ecological characteristics and serves as an essential metric for assessing soil quality. Soil microorganisms exhibit high sensitivity to ecological perturbation, with their diversity and community composition being profoundly affected by field management practices including tillage, fertilization, and irrigation [6; 7]. Soil organic carbon (SOC) is a critical determinant of plant productivity and soil fertility, and its maintenance and enhancement are essential for ensuring food security [8; 9]. Active soil organic carbon (SOC) fractions are susceptible to decomposition, volatilization, and instability, making them easily absorbed and utilized by plants and microorganisms. Additionally, these fractions serve as the primary energy source for soil microbes, which play a crucial role in SOC turnover and the regulation of nutrient availability for crops [10; 11]. Methods such as straw returning to the field and conservation tillage can be adopted to optimize agricultural practice strategies in order to increase the input of exogenous carbon, improve the soil microbial environment, and further enhance the crop yield [12; 13]. The selection of appropriate tillage regimes is crucial for improving soil structure, enhancing crop cultivation suitability, optimizing resource utilization, maintaining soil fertility, and increasing crop yields [14]. Different tillage practices demonstrate significant variations in their effects on soil nutrient content and microbial communities [15]. Straw returning represents an environmentally sustainable agricultural production measure that enhances nutrient effectiveness, improves soil structure, and induces shifts in the diversity, structure, and composition of soil microbial communities [16; 17; 18]. As a nutrient-rich resource, straw incorporation increases the input of SOC content. The straw decomposition process, mediated by soil microorganisms, converts stable organic carbon in straw into labile organic carbon fractions, thereby elevating the content of active organic carbon in the soil [19]. Straw return is commonly implemented using different tillage practices. Studies have shown that straw return with conventional tillage increased SOC content by 3.9-11.2% in the 10-40 cm soil layer [20]. Compared to conventional tillage, no-tillage (NT) practices are more conducive to forming stable soil aggregates and reducing soil erosion. Straw return combined with NT reduced the soil disturbance frequency relative to conventional tillage, effectively maintaining soil stability [21]. A combination of rotary tillage (RT) and straw returning has been widely recognized as a crucial sustainable management practice, which can effectively mitigate soil erosion and enhance SOC sequestration [22]. [PERSON]'s [23] research confirmed that deep tillage (PT) practice exhibits higher microbial diversity indices, dominance indices, and abundance indices. Additionally, studies showed that the model of deep tillage with straw return increased soil microbial activity by altering the soil structure of the lower plow layer [24]. Black soil is primarily distributed in the mid to high latitudes globally and is the most suitable soil type for crop cultivation among arable land resources. Jilin Province, located in the northeastern part of China, is situated within one of the world's four famous black soil belts. According to statistics, the arable land area in the typical black soil region of Jilin Province is approximately 6.54 million hectares, accounting for more than one-fourth of the total typical black soil arable land area in the country [25].