# Using an Uptake Enhancer to Mitigate Nitrogen Leaching While Enhancing Uptake Efficiency
## 4 Discussion  
### Effect of Uptake Enhancer on N Distribution through a Soil Profile  
The application of the uptake enhancer in sandy soil profiles has provided significant insight into the N distribution in nutrient management. At the initial sampling time (4 weeks), the CFA treatment demonstrated the highest significant increases in N content in the upper soil layers where crops mainly acquire nutrients, preventing N leaching by 194% at 0-10 cm soil depth and 186% at 10-20 cm soil depth. Conversely, the lowest N content was found in the CNTRL treatment across all depths, with no significant variations across depths due to the nature of the soil. Nitrogen availability in the early stages of growth is greatly influenced by soil structure and texture. Sandy soil profiles frequently show rapid drainage, which may cause nutrients to leach more quickly. Additionally, N is mobile and tends to disperse relatively evenly across the soil profile in well-drained soils, which reduces the variation in its availability across soil depths [30]. These findings demonstrate how well the uptake enhancer can retain N in the upper soil layers and prevent it from leaching. The results are in line with the study conducted by [PERSON] et al. [31], which showed the positive impact of an uptake enhancer on nutrient distribution and retention in various soil types.  
At week 8, significant differences between treatments were observed across the upper soil layers (0-20 cm), particularly treatment CFA, which maintained stable N content in the upper soil layers. In contrast, the other treatments exhibited higher leaching of N at deeper soil depths (mainly below 20 cm). The FA treatment proved less effective without a crop, while the CFA treatment significantly reduced leaching. According to [PERSON] et al. [32], uptake enhancers are crop-dependent, so crops should be added to enhance their effectiveness.  
The impact of uptake enhancer treatment was further observed at weeks 12 and 16, with significant differences across soil depths of most treatments, except for the CNTRL treatment. These findings collectively highlight the importance of uptake enhancer application in improving N retention, particularly in the upper soil layers, which are crucial for crop nutrient uptake.  
When comparing N distribution at different sampling times, the CFA treatment consistently surpassed other treatments in retaining N in the upper soil across all growth stages, minimizing leaching and facilitating better N uptake by oats. Though less than the CFA treatment, the FA treatment also had excellent results, demonstrating the adjuvant's beneficial effects when combined with fertilizer. Treatments with the uptake enhancer exhibited the highest N content in the upper soil layers and the lowest in the deeper soil layers. Conversely, the N concentration increased with soil depth in treatments that had no uptake enhancer. These findings are supported by observed variations in N content across sampling times, which reflect the complex interactions between soil characteristics, nutrient availability, and plant physiology [33]. The use of the uptake enhancer can greatly improve N retention in the root zone, thereby reducing leaching and promoting more efficient use of N by crops.