# Effect of Precision Nitrogen Fertilization of Grassland on Soil Microbial Structure
## 3 Results and Discussion
### Spatial Correlation Coefficients Between Isolated Actinomycetes Species and Soil Nitrate Content  
To account for the spatial nature of the parameters studied, the spatial correlation method was employed. For the superficial soil layer (0.05 m), a spatial correlation coefficient of \(-\)0.52 was obtained (Table 1). Similarly, for the soil stratum at a depth of 0.15 m, a spatial correlation coefficient of 0.19 was found between the abundance of _Streptomyces albidoflawus_ and _Streptomyces venezulae_ and the nitrate content of the soil profile. A high value of the spatial correlation coefficient was recorded in the soil layer at a depth of 0.25 m, where it was \(-\)0.59 for _Streptomyces albidoflavus_ and \(-\)0.57 for _Streptomyces venezulae_. In the case of the deepest soil layer (0.35 m), a lower spatial correlation coefficient was observed, with a value of 0.26 for _Streptomyces albidoflavus_ and 0.22 for _Streptomyces venezulae_.  
The analysis of the spatial nature of the studied parameters using the spatial correlation method offers valuable insights into the relationship between actinomycetes abundance and nitrate content in the soil profile. The results reveal variations based on the depth of the soil layer examined. For the surface soil layer (0.05 m) and the layer at a depth of 0.15 m, similar spatial correlation coefficients were observed: \(-\)0.52 for the abundance of _Streptomyces albidoflavus_ and 0.19 for _Streptomyces venezulae_ in relation to nitrate content. In contrast, a higher spatial correlation coefficient of \(-\)0.59 for _Streptomyces albidoflavus_ and \(-\)0.57 for _Streptomyces venezulae_ was recorded in the soil layer at a depth of 0.25 m. These results suggest a stronger relationship between the abundance of these actinomycetes and the nitrate content in this specific soil layer. In the deepest soil layer (0.35 m), lower spatial correlation coefficients were obtained, measuring 0.26 for _Streptomyces albidoflavus_ and 0.22 for _Streptomyces venezulae_. This indicates a reduced influence of nitrate content on the abundance of these actinomycetes in the deeper soil layer. Overall, the analysis of spatial correlation coefficients suggests that the abundance of actinomycetes is related to nitrate content in the various layers of the soil profile within the study area. Research by [PERSON] et al. [76] indicates that total nitrogen content in the soil can significantly impact microbial biomass and activity. Their findings demonstrate that the structure and distri  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{_Streptomyces albidoflavus_} & \multicolumn{4}{c}{_Streptomyces venezulae_ [cfu/g Soil]} \\ \cline{2-7}  & **Depth [m]** & **0.05** & **0.15** & **0.25** & **0.35** & **0.05** & **0.15** & **0.25** & **0.35** \\ \hline \multirow{4}{*}{
\begin{tabular}{c} Nitrate content \\ [mg/100 g soil] \\ \end{tabular} } & 0.05 & \(-\)0.52 & & & \(-\)0.52 & & \\ \cline{2-7}  & 0.15 & & 0.19 & & & 0.19 & \\ \cline{1-1} \cline{2-7}  & 0.25 & & \(-\)0.59 & & & \(-\)0.57 & \\ \cline{1-1} \cline{2-7}  & 0.35 & & & 0.26 & & & 0.22 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Spatial correlation coefficients between isolated actinomycetes species and soil nitrate content.  
bution of actinomycetes communities are closely tied to the availability and quality of total nitrogen. Furthermore, studies by [PERSON] et al. [77] and [PERSON] et al. [78] have identified clear positive correlations between total nitrogen content and actinomycetes abundance, underscoring the importance of this nutrient in shaping soil microbial composition. Additionally, changes in total nitrogen content have been shown to affect microbial composition variation, as confirmed by [PERSON] et al. [79]. Their study highlighted an upward trend in the abundance of Actinobacteria in soil in response to nitrogen addition, suggesting that alterations in nitrogen content can lead to shifts in the functioning and metabolism of soil microorganisms.