Efficiency of TerraCottem hydrophilic polymer in rain-fed afforestations

Drought is an important problem in habitat restoration and afforestation of woodlands in arid and hot regions. To overcome this problem and achieve a proper and an easy method to store moisture in the soil, one of hydrophilic polymer called "TerraCottem" was compared with other methods of water conservation. In this research, potential of polymer in water holding and absorption and their effects on survival and growth characteristics of Moringa peregrina were studied. In order to investigate the effect of moisture conservation methods on M. peregrina planting, a trial conducted as split-plot design with three replicates in which main plots consisted of: seed and pot seedling and sub/plots consisted of five conservation methods (straw and dried residual at the bottom of planting dig, tourkinest, plastic film, polymer materials mixed with soil and ditch) at Bashagard region in 2008 for four years. The results showed that absorption and water-holding capacity decreased with time by the polymers, so that after 2200 days reduced to zero. The results indicated that there were significant differences between the moisture conservation methods with respect to Moringa mortality. The highest survival belonged to dried residual and plastic film treatments 24% and 14%, respectively. The lowest survival belonged to polymer material and ditch treatments. There were significant differences between the storage systems in respect to M. peregrina growth characteristics: total height, stem diameter and canopy cover (p<0.01) and dry residual, tourkinest and plastic film treatments had the greatest performance whereas polymer and ditch showed lowest performance. Therefore, with reducing the polymer's ability for absorbing and holding water in long term, application of polymer in rain-fed plantations in hot and dry regions with medium to heavy textured soils and alkaline is not recommended.