Data and Data analysis

Prior to statistical analysis, normality and homogeneity of the data were confirmed using the Shapiro-Wilk test and Bartlett test, respectively. The different effects on wheat fields between tradition fertilizer and new fertilizer were detected by ANOVA. The contribution of different types of fertilizers with biochar on the wheat field was detected by ANOVA analysis. The effect of CCT fertilizers adding different carbon contents of biochar on wheat fields was detected by an unpaired t test. Linear regression was used to explore the relationship between plant NUE and wheat biomass and yield, respectively. The Spearman correlation was used to detect the correlation among variables.

From the QQ plot (Fig.1), the points align closely with the 45-degree reference line, indicating that the data follows a normal distribution. There are no significant deviations in the tails, suggesting the absence of extreme skewness or heavy tails.

     In Fig. 2a, biomass exhibits the highest values among the categories, with a median close to 5000 and a relatively wide interquartile range (IQR). The whiskers are long, suggesting a broad data range with some potential variability in extreme values. The median for yield is approximately 2500, lower than that of biomass. The IQR is narrower, indicating less variability in the middle 50% of the data. The whiskers extend moderately, suggesting a relatively balanced distribution. The C uptake of plants has a median slightly above 2000 and a wider IQR compared to the C uptake of grain. C uptake of grain has the lowest median and the narrowest IQR, indicating minimal variability and a tightly clustered data set. Total N uptake has a median similar to Yield, but its IQR is wider, suggesting more variability in the central data. The whiskers are moderately extended, indicating some spread in values without extreme outliers.

        In Fig. 2b, The S uptake of plant has a median slightly below 5, with a moderately wide interquartile range (IQR). The whiskers are relatively long, indicating a broader spread of data, suggesting more variability in sulfur uptake at the plant level. The S uptake of grain has the lowest median (close to 2) and the narrowest IQR, indicating that the data is tightly clustered around the center. The shorter whiskers suggest less variability, making this category the most consistent among the three. The Total S uptake category has the highest median (around 6) and the widest IQR, indicating significant variability in the data. The upper whisker extends further, suggesting higher values in the dataset and a potentially broader range.

       In Fig. 2c,  The N uptake of plant has the smallest median and interquartile range (IQR) among the three categories. The median appears close to 10. The IQR is narrow, and the whiskers are short, indicating limited variability and a tightly clustered distribution. The N uptake of grain has a higher median than N uptake of plant (approximately 50). The IQR is wider, and the whiskers extend further, showing greater variability in nitrogen uptake at the grain level. The Total N uptake category has the highest median (around 75) and the widest IQR, suggesting significant variability. The whiskers are the longest among the three categories, indicating a broader range of values and potential outliers.