## 3 Results  
### Pesticide Residues in Soil Samples  
To assess the effects of different tillage practices on pesticide residue levels in agricultural soils, soil samples were collected after the autumn harvest under three distinct treatments: CK, SS, and ST. The study focused on five commonly used herbicides: atrazine, acetochlor, alachlor, nitosulfuron, and mesotrione (Table 1).  
The residue levels of selected herbicides in agricultural soils are as follows: atrazine concentrations ranged from ND to 21.10 \(\upmu\)g/kg, with a mean of 5.28 \(\upmu\)g/kg and a standard deviation of 6.23 \(\upmu\)g/kg. The CV was calculated as 1.18, indicating moderate variability in its distribution.  
Acetochlor displayed a much broader concentration range, from 2.29 to 120.61 \(\upmu\)g/kg, with an average of 25.26 \(\upmu\)g/kg and a standard deviation of 26.79 \(\upmu\)g/kg. The CV is 1.06.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**Tillage** & **Pesticide** & **Min** & **Max** & **Mean** & **SD** & **CV** \\ \hline \multirow{6}{*}{CK} & Atrazine & ND & 11.62 & 5.06 & 5.70 & 1.13 \\  & Acetochlor & 19.35 & 30.62 & 23.78 & 4.47 & 0.19 \\  & Alachlor & ND & ND & ND & ND & ND \\  & Nicosulfuron & ND & ND & ND & ND & ND \\  & Mesotrione & ND & ND & ND & ND & ND \\ \hline \multirow{6}{*}{SS} & Atrazine & ND & 12.31 & 3.94 & 5.12 & 1.30 \\  & Acetochlor & 2.29 & 48.79 & 23.66 & 18.34 & 0.78 \\  & Alachlor & ND & 5.71 & 1.02 & 2.30 & 2.25 \\  & Nicosulfuron & ND & ND & ND & ND & ND \\  & Mesotrione & ND & ND & ND & ND & ND \\ \hline \multirow{6}{*}{ST} & Atrazine & ND & 21.10 & 6.83 & 8.25 & 1.21 \\  & Acetochlor & 4.38 & 120.61 & 28.34 & 45.46 & 1.60 \\  & Alachlor & ND & ND & ND & ND & ND \\  & Nicosulfuron & ND & ND & ND & ND & ND \\  & Mesotrione & ND & ND & ND & ND & ND \\ \hline \multirow{6}{*}{Total} & Atrazine & ND & 21.10 & 5.28 & 6.23 & 1.18 \\  & Acetochlor & 2.29 & 120.61 & 25.26 & 26.79 & 1.06 \\ \cline{1-1}  & Alachlor & ND & 5.71 & 0.34 & 1.34 & 3.95 \\ \cline{1-1}  & Nicosulfuron & ND & ND & ND & ND & ND \\ \cline{1-1}  & Mesotrione & ND & ND & ND & ND & ND \\ \hline \end{tabular} ND: not detected; CV: coefficient of variance.  
\end{table}
Table 1: Pesticide concentrations in selected soils.  
Alachlor residues were generally low, ranging from ND to 5.71 \(\upmu\)g/kg, with an average of 0.34 \(\upmu\)g/kg. The CV is 3.95. Neither incosulfuron nor mesoftrone was detected in any of the soil samples analyzed.  
Under CK conditions, Atrazine concentrations ranged from ND to 11.62 \(\upmu\)g/kg, with a mean of 5.06 \(\upmu\)g/kg and a coefficient of variation (CV) of 1.13. Acetochlor showed a narrow range of 19.35-30.62 \(\upmu\)g/kg, with an average of 23.78 \(\upmu\)g/kg and a CV of 0.19. Alachlor, nicosulfuron, and mesoftrone were not detected.  
In SS treatment, Atrazine residues ranged from ND to 12.31 \(\upmu\)g/kg, with an average of 3.94 \(\upmu\)g/kg and a coefficient of variation (CV) of 1.30. Acetochlor concentrations ranged from 2.29 to 48.79 \(\upmu\)g/kg, averaging 23.66 \(\upmu\)g/kg, with a CV of 0.78. Alachlor was detected in some samples, ranging from ND to 5.71 \(\upmu\)g/kg, with an average of 1.02 \(\upmu\)g/kg and a CV of 2.25. Nicosulfuron and mesoftrone were not detected.  
Under ST conditions, Atrazine residues ranged from ND to 21.10 \(\upmu\)g/kg, with an average of 6.83 \(\upmu\)g/kg and a CV of 1.21. Acetochlor showed the highest variability across all treatments, ranging from 4.38 to 120.61 \(\upmu\)g/kg, with a mean of 28.34 \(\upmu\)g/kg and a CV of 1.60. Alachlor, nicosulfuron, and mesoftrone were not detected.