Porous block mulch:

water evaporaiion losses from the soil surface constitute one of the inevitable inefficiencies of irrigation. Many types of soil coverings or mulches have been investigated for reducing evaporation losses. Studies have shown that a porous mulch can be made by cementing pea gravel with a small amount of fine sand and cement mortar to hold the gravel grains in a solid array without filling the pores between grains. Such a mulch has favorable characteristics not only for water conservation, but for reducing salinity hazards, preventing soil compaction and minimizing weed control. Water conservation and salinity become even more important in arid or desert areas. For ornamental plantings, such a mulch can be cast in block form for use over the soil surface much like stone or concrete blocks.