Analysis of spatial soil moisture variation on a cracking clay soil for optimizing sprinkler irrigation management

The objective of this research was to assess the impact of soil cracks on soil moisture distribution under various sprinkler irrigation applications and to identify the optimal irrigation strategy. The assessment was made for six irrigation events using: hand shift-set sprinkler system, lateral move system with fixed sprayer heads and lateral move system with rotating sprinklers. The experiments were conducted on two adjacent fields. Each field was divided into 2x2 m grids that covered 62 sampling locations. The soil physical and hydrological properties, field slope, soil texture and infiltration rate were defined. Since the soil was cracking clay, further analysis was conducted on the crack dynamics, size and distribution using image analysis techniques. Improving the irrigation system application uniformity did not always result in higher uniformity of the surface soil moisture content (0-25 cm). The event that best enhanced soil moisture distribution was observed when the field received 32 mm water application. The soil was at a relatively high initial soil moisture content of 25%. At this soil moisture content, the extent of soil cracking on the drainage water was limited