Investigating the Relationship between the Amount of Total Nitrogen and Some Soil Characteristics in Zarin Shahr Region

The purpose of this research was to investigate the impact of pH, EC, and organic carbon (OC) on the amount of total nitrogen in the soil of the Zarin Shahr Region using statistical analyses (borderline analysis and step-by-step regression). In the Zarinshahr region, a comprehensive study was conducted for a duration of one year across all four seasons. The study employed GPS technology to select a total of 60 points in agricultural, tree plantations, and bare soil areas while ensuring an average distance of 546 meters between each point. The plots areas were 50x50x20 cm in length, width, and height. The various soil samples collected from these plots were analyzed. Then, the maximum reaction of a biogeochemical process to a certain environmental factor was determined using borderline analysis. According to the findings, the soil's EC exhibited higher readings during the hotter seasons of the year, in comparison to other seasons. Specifically, during the summer, the maximum value of this parameter was approximately 1587 dS/m, while in the winter, the values were nearly 1140 dS/m. Also, pH levels of the soil was generally alkaline. The seasonal variations in soil OC and organic matter percentage were evident, with notably lower values (ranging from 0.04-2.52) in the autumn and winter, followed by a marked increase during the summer and spring (0.12-2.39). Boundary line analysis was used to investigate the relationships between variables and the values of indicators that caused the maximum increase in soil nitrogen. It was ascertained that OC percentage and soil nitrogen percentage exhibited a significant linear correlation in all land uses. Hence, increase in OC percentage resulted in an increase in the total nitrogen content in the soil. The step-by-step regression analysis in a systematic manner revealed that, within the variables under investigation, the percentage of total nitrogen in the soil can be determined based on the impact of two key parameters, namely, EC and the percentage of OC. The results suggest that use of boundary line analysis and step-by-step regression represent a viable approach for determining the effects of the significant factors on the levels of nitrogen content in the soil.