Assessment of Soil-Amendment Mixtures for Subsurface Drip Irrigation Systems

Subsurface drip irrigation (SDI) is the most water saving irrigation system. Inorganic soil amendments (IA) emplaced around the irrigation tubes can increase the water retention potential and might reduce the loss of water due to leaching. We analysed mixtures of sand for golf putting green construction and IA additions up to 10 mass percent by measuring their water retention in soil cores and modeling soil water storage and drainage under a reaslistic water application schedule. A simulation of the soil water dynamics was used to assess the effect of IA in terms of irrigation water conservation and drainage losses. Two different climatic situations, represented by climatic data of Brussels, Belgium (humid) and Cordoba, Spain (arid) were compared in the simulation. The irrigation schedules for each location with respect to the soil amendment were calculated employing a deficit-based protocol. The addition of IA increased the available water capacity and resulted in a significant reduction of scheduled irrigation events and also a reduction of annual irrigation water requirements and water loss due to drainage for both climatic conditions. The observed water saving effect was larger for humid climatic conditions. Thus, the combination of subsurface drip irrigation with IA addition leads to additional water saving for irrigation on golf putting greens.