Water loss to interception has been reported to account for a significant portion of the water budget in the tallgrass prairie. However, methods used to quantify such interception water loss have some significant limitations. Notably, direct quantification of interception using rainfall collectors under grass canopy was unable to count for both stemflow and litter layer interception.  Collectively, it could have underestimated water reaching soil and thereby over-estimated water loss through grass interception. In order to evaluate the potential impact of land use and land change such as woody plant encroachment and conversion of common pasture to energy feed stock production on water cycle at both watershed and regional scale in the Great Plains, it is important to precisely quantify each component of the water budget in tallgrass prairie.  We conducted a field experiment in the Oklahoma State University Range Research Station located in the eastern Great Plains. In this study, we directly quantified water loss by the tallgrass interception using an automated collecting tray technique, which directly counted stemflow and litter water storage. We also measured the tallgrass interception by placing rainfall collectors under the grass canopy at the same site. 
Results/Conclusions

Our primary results indicated that the average interception water loss measured by the automated collecting tray technique was generally lower than that calculated based on throughfall collectors. In addition, the automated collecting tray technique was able to produce simultaneous response between individual precipitation event and associated interception process. We concluded that precipitation interception based on throughfall collectors could have over-estimated grass interception water loss.