Analysis of Water Infiltration Characteristics and Hydraulic Parameters of Sierozem Soil under Humic Acid Addition

The farmland in Yinchuan is composed of sierozem soil, which characterized by high sand content and low organic matter content, resulting poor water-holding capacity weak soil structure. Humic acid a natural polymer amendment. It critical to study how humic affects water infiltration at the microlevel. A one-dimensional vertical experiment was conducted explore adding different amounts (0, 1%, 2%, 3% 4%) affected characteristics hydraulic parameters soil. results revealed that wetting front cumulative decreased with increase addition. When time 90 min, 4% treatments 6.50%, 10.00%, 15.00% 21.00% lower than CK (0 for CK), volume 4.50%, 11.14%, 18.42% 23.60% CK, respectively. Among three models created Philip, Horton Kostiakov, Kostiakov model (R2 > 0.95) could more accurately describe process area. After infiltration, moisture each layer increased acid, improved Using Hydrus-1D calculate parameters, we found addition parameters. With amount addition, retention θr saturated θs were positively correlated negatively conductivity Ks reciprocal air-entry α. showed improve rapid loss