Effects of irrigation on soil physical properties in predominantly pastoral farming systems: a review

This paper reviews the effects of irrigation on soil physical properties, particularly soil water movement and storage, under predominantly pastoral systems. Few studies address how irrigation impacts these in temperate climates, with very few studies under modern spray irrigation and intensive pastoral farming. Irrigation generally means intensive land use will occur. It is difficult to uncouple factors affecting physical conditions such nutrient cycling, land use, stock class, grazing management and animal treading. Irrigation (with associated increased land use intensity) tends to alter soil physical properties, changing them to be like soils formed under higher rainfall particularly in arid and semi-arid climates. Changes in physical properties under irrigation in temperate and sub-humid climates were more variable. Some studies showed increased available water capacity, while others showed no change. Knowledge gaps include effects of irrigation intensification on soil physical properties under modern farm systems to improve process, management, spatial and temporal information.