The use of alternative water holding amendments will become more important over time, especially in regions with redwater shortage. Watwer absorbent materials (natural and synthetic) can absorb water as much as hundreds times their weight. This superabsorbent’s characteristic makes them useful for water conservation. The objectives of this study were to evaluate the effect of synthetic super absorbent amendment (i.e, Hydrogel) and natural super absorbent amendment (i.e, Pumice, Compost, Manure fertilizer and Perlite), on soil water retention characteristic curve (WRC) using RETC computer model in a laboratory trial, effect of these materials on the soil compaction and some growth indicies of 4 plants include: Fraxinus, Plantanus, Cupressus and Olea in 3 different soil textures. The field trials were as split plot in the random complete blocks model. The hydrogel Superab A200 in two levels, 4 and 6 g/kg, Pumice, Compost, Manure fertilizer and Perlite in two different levels, 40 and 60 g/kg and all couple mixture of amendments were mixed with three soil textures of clay, clay loam sand and loam. The results of the soil water retention model showed that, hydrogel in clay loam sand and loam soils is more effective than clay soils and caused the permanent wilting point water content (q pwp ), saturated water content (q s ) and available water (AW) to increase. The best treatment in clay soil was Compost+Perlite available water (AW) increased 1.56 fold of control soil. Pumice+Perlite decresed compaction of the clay control soil, from 2017(gr/cm 3 ) to 1498 (gr/cm 3 ). In loam soil AW increased 2.42 fold of control. By use of Perlite+Manure fertilizer compaction of soil was observed to decrease 247 (gr/cm 3 ) copaired with control sample. In the field trial, the results of the statistical analysis showed that there is significant difference in growth ind ices by using Pumice+Hydrogel in loam soil. In clay loam sand soil the results of retention curve model showed the most effective treatment is Compost+Hydrogel that increased AW 3.3 fold of control. Compaction in clay loam sand soil by using Perlite+Manure fertilizer was observed to decrease 397 (gr/cm 3 ) copaired with control sample. Statistical analysis showed that the most effective treatments on growth ind ices in clay loam sand were Compost + Hydrogel and Manure fertilizer + Hydrogel. Key words: Soil moisture, Water retention curve, Super absorbent polymer, Compaction
