Investigation the Effect of Polyvinyl Acetate Polymer, Acid Biochar and Wheat Straw Cellulose Hydrogel on Water Retention Capacity in a Sandy Soil

The drought crisis reveals the necessity of saving and optimal use of water in various sectors, especially in agriculture. One of the strategies to optimize use of water resources is the application of organic materials and natural (bio) and synthetic sorbents. The purpose of this study was to investigate the effect of polyvinyl acetate polymer, wheat straw biochar and cellulose hydrogel on the water retention capacity (at suctions 33, 100, 300, 500 and 1500 kPa), bulk density, aggregate stability and amount of organic carbon in the sandy soil. Therefore, a factorial experiment was conducted in a completely randomized design with three replications. A sandy soil was collected from the southeast Ahvaz. The factors included (1) amendment (Polyvinyl Acetate polymer, biochar and cellulose hydrogel of wheat straw), (2) amendment concentration (Polyvinyl Acetate polymer: 5 and 10 g/L, biochar and cellulose hydrogel: 1 and 3 % w/w) and (3) time duration (21, 42, 63 and 126 days). The results showed that all experimental treatments, at all pressure heads, increased soil water retention significantly (p<0.01). The addition of amendments reduced the soil bulk density and increased the organic carbon and aggregate stability. Minimum bulk density was observed in the cellulose hydrogel and biochar treatments at 126-days and in the polyvinyl acetate polymer at 21-days. Maximum organic carbon and aggregate stability were observed in the cellulose hydrogel treatment at 126-days. In hydrogel treatments with passing time, aggregate stability and water retention increased, but water retention of polyvinyl acetate polymer decreased with increasing time. Moisture absorbent biopolymer is a suitable replace to super absorbent synthetic polymers because not only increase soil organic matter but also enhance soil aggregate stability and water retention capacity.