# Changes in Soil Moisture Improved by High-Performance Ester Materials under Dry-Wet Cycles
## 3 Results and Discussion  
### The Improvement Effect of High-Performance Ester Materials on Soil Water Holding Capacity  
The grading curve of the soil sample used in the study is shown in the Figure 4. The steep grading curve means uniform soil particles, poor grading, and possibly unfavorable internal pore structure of the soil, which is not conducive to soil water retention. In order to improve the water holding capacity of the soil, we used high-performance ester materials. Figure 4: Soil particle size distribution curve. Figure 3: Planting test. Polymer water-retaining materials can enhance the water retention and storage performance of soil, while polymer adhesive materials can enhance the bonding force between soil particles. Figure 5 shows the improvement effect of high-performance ester materials on soil's water holding capacity; it can be seen that the water holding capacity of the test group with different material ratios under various dry-wet cycles is improved. Throughout all dry-wet cycles, the water holding capacity of the test group with added materials was higher than that of the control group without added materials. In test groups 1-9 with added materials, it was found that the soil's water holding capacity increased with the increase of water-retaining materials, indicating that water-retaining materials played a key role in enhancing the soil's water holding capacity. As the adhesive material increased, the water holding capacity of the soil increased at first, then decreased; the maximum value appeared in test group 6. Test groups 10-12 only contained water-retaining materials, while groups 13-15 only contained adhesive materials. As shown in Figure 5b, it can be seen that both materials can independently improve the soil's water holding capacity; even after various dry-wet cycles, their water holding capacity is higher than that of the control group CK. As shown in the Figure 5, with the increase of water-retaining materials, the soil water holding capacity also increases. As the adhesive material increases, the soil moisture capacity first increases and then decreases. And from the graph, we found that the ester materials have an optimal ratio in improving soil's water holding capacity. To explore the role of high-performance ester materials in improving soil's water holding capacity, variances in the data from the test's result were analyzed. Results from the 0 th, 4 th, 8 th, and 20 th dry-wet cycle tests of test groups 1-9 were selected for variance analysis, with the added amount of adhesive materials and water-retaining materials used as independent variables and the soil moisture holding capacity as the dependent variable. For variable water-retaining materials, the significance \(p\)-values of the F-test analysis of the 0 th, 4 th, 8 th, and 20 th dry-wet cycle test data were 0.039, 0.018, 0.043, and 0.039, respectively, all less than 0.05, showing that water-retaining materials have a significant impact on the water holding capacity of soil. For variable adhesive materials, the analysis of the F-test results from the data from the 0 th, 4 th, 8 th, and 20 th dry-wet cycle tests show that the significance \(p\)-values were 0.07, 0.198, 0.131, and 0.124, respectively, which were greater than 0.05. This analysis showed that adhesive materials do not have a significant impact on soil's water holding capacity. Analysis from the test results above revealed that high-performance ester materials can significantly improve soil's water holding capacity even under various dry-wet cycles. Water-retaining materials play a major role in improving the soil's water holding capacity, and adhesive materials can also enhance the soil's water holding capacity to a certain extent. However, excessive adhesive materials can have a negative effect and cause soil compaction, limiting water absorption and the expansion of water-retaining materials. Therefore, there is an optimal ratio of high-performance ester materials for improving soil's water holding capacity.