A soil amendment is any material added to a soil to improve its physical properties, such as water retention, permeability, water infiltration, drainage, aeration and structure. soil amendments are not the same thing as mulches, although some mulches are also used as amendments. To be effective, amendments must be thoroughly mixed with or injected into the soil, not merely buried.

There are two broad categories of soil amendments: organic and inorganic. Organic amendments come from something that is or was alive. Inorganic amendments, on the other hand, are either mined or man-made. Organic amendments include fish hydrosate, sphagnum peat, wood chips, grass clippings, straw, compost, manure, biosolids, and wood ash. Inorganic amendments include vermiculite, perlite, tire chunks, pea gravel and sand.


The project tested five soil amendments products in separate turf areas equipped with SMART irrigation controllers. These controllers use probes that communicate soil moisture levels back to the main unit, which uses the information to determine irrigation schedules and run times for each zone automatically. This automation provided a baseline for comparing irrigation intervals between theamendment test plots.

Products tested included Organic Gem, fish hydrosate, CBX (complete biological extract), an organic plant mineral compound, BioFlora, a bio-organic nutritional system, and Nutrimoist and Enviomoist, polymer crystals injected into the ground that hydrate when they come in contact with water. Each product was applied according to manufacturer specifications at prescribed intervals. Generally, these products were applied within the first 7-10 days of each month.

The primary objective of the test was to analyze how selected amendments impacted soil water retention characteristics, grass health, and irrigation needs. Performance of each product was tracked using a combination of measurements. A pentrometer — a soil compaction probe — was used to measure soil compaction within the upper 8 inches of warm season turfs. Complete soil samples, performed at various intervals during the study, tested for salinity and nutrient levels. Finally, the visual appearance of turf plant health was documented using photographs.


The genesis of the DesertWise study at PERA Club came from Phoenix area city's and parks which were looking for direction on the best products to help them conserve water. The conservation of water is a key component for these cities to help us all successfully live in the desert. This study has been a huge step on SRP's part to help towards meeting that goal. If these findings are applied Arizona and other arid AND non-arid regions can save water and preserve this natural resource.

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