## 3 Results
### Distribution Ratio and Correlations of Soil Active Nitrogen Fractions  
The application of organic materials changed the distribution of active nitrogen fractions in TN (\(p<0.05\)), as shown in Table 2. Compared with CK, the application of organic materials reduced the distribution ratio of N\({}_{\rm min}\) in TN with the exception of April 2019, where the N\({}_{\rm min}\)/TN ratio was increased. In October 2019, the highest N\({}_{\rm min}\)/TN ratio was recorded under FG treatment; however, there was no significant difference in the N\({}_{\rm min}\)/TN ratio across the treatments. The application of organic materials increased the distribution ratio of ATN in TN by 29.43-74.70%. Moreover, the distribution ratio of PON/TN increased by 31.05-76.66%. The distribution ratio of DON in TN increased by 4.05-53.52%. The MBN/TN ratio for MS treatment was significantly different from the other treatments from October 2018 to April 2019 (\(p<0.05\)); however, there was no significant difference between the treatments in October 2019. Within the same treatment, the proportion of soil active nitrogen fractions in TN was different, with PON taking the largest proportion, followed  
Figure 8: Application effects of different organic materials on soil N\({}_{\rm min}\) content at different sampling dates. Lowercase and different letters indicate statistically significant differences at \(p<0.05\) between treatments.  
Figure 7: Application effects of different organic materials on soil NO\({}_{3}\)\({}^{-}\)-N content at different sampling dates. Lowercase and different letters indicate statistically significant differences at \(p<0.05\) between treatments.  
by DON, N\({}_{\rm min}\), and MBN, indicating that PON contributes the most to soil nitrogen and MBN the least. The proportion of the soil ATN content was higher than N\({}_{\rm min}\) in soil TN.  
As shown in Table 3, there was a correlation between the active nitrogen components and TN. The Pearson correlation analysis showed that there was a significant positive correlation between soil ATN and TN (\(p\) < 0.01), indicating that the change in characteristics of ATN fractions was consistent with the changes in TN content. Moreover, TN had a significant positive correlation with PON (\(p\) < 0.01) and MBN (\(p\) < 0.05), while PON, DON, and MBN were positively correlated with each other. There was a significantly positive correlation between PON and ATN (\(p\) < 0.01), while soil N\({}_{\rm min}\) and TN was positively correlated but not significant. Similarly, N\({}_{\rm min}\) positively correlated with ATN; however, the correlation was not significant. Moreover, there was a correlation between organic and inorganic nitrogen fractions. There was a significantly positive correlation between MBN and NO\({}_{3}\)\({}^{-}\)-N (\(p\) < 0.01) and PON and NO\({}_{3}\)\({}^{-}\)-N (\(p\) < 0.05); however, DON and NH\({}_{4}\)\({}^{+}\)-N were significantly negatively correlated (\(p\) < 0.05). The correlation between the soil active nitrogen fractions and TN revealed that the effect of ATN fractions on TN was higher than that of the N\({}_{\rm min}\) fractions. Among the ATN fractions, PON largely contributed to the TN content in soils.