Estimating Soil Water Content From Surface Digital Image Gray Level Measurements Under Visible Spectrum.

Yuanjun Zhu Sr.1, yunqiang Wang Sr.2, mingan shao Sr.2 and Robert Horton3, (1)institute of soil and water conservation, Chinese Academy of Sciences, Shaanxi, China, (2)institute of geographical sciences and natural resources research, Chinese Academy of Sciences, Beijing, China, (3)Agronomy Department, Ames, IA