مجله آب و خاک (Jun 2017)
Comparison the Efficiency of Aquasorb and Accepta Superabsorbent Polymers in Improving Physical, Chemical, and Biological Properties of Soil and Tomato Turnover under Greenhouse Condition
Abstract
Introduction: Water shortage in arid and semiarid regions is the most serious factor in limiting agricultural activities as it leads to the rapid reduction of yields from both a quantitative and qualitative perspective. Under conditions of water scarcity, leaf temperature rises, which causes plant wilting and premature senescence of leaves and, eventually, severes reduction of dry matter production. Use of high-efficient irrigation practices, improvement of soil's physical properties, and use of soil amendments such as superabsorbent polymers are some ways of compensating for water shortage, especially during the growing season. Some materials such as plant residues, manure, various types of compost, and superabsorbent polymeric hydrogels can store various amounts of water and thus increase water retention and storage capacity of soils. Superabsorbent hydrogels, which are also called superabsorbent polymers (SAPs) or hydrophilic polymeric gels, are hydrogels that can absorb substantial quantities of water. Hydrogels are a class of polymeric materials having network structures (with physical or chemical crosslinks) that are very capable of swelling and absorbing large amounts of water. These materials are formed from water-solublepolymers by crosslinking them either using radiation or a crosslinker. Superabsorbents are widely used in many products such as disposable diapers, feminine napkins, soils for agricultural and horticultural purposes, gel actuators, water blocking tapes, medicine for the drug delivery systems and absorbent pads where water absorbency or water retention is important. Water is a major constraint for crop growth in arid and semi-arid regions, as the precipitation is low and uncertain in these areas. Efficient utilization of meager soil and water resources necessitates the adaptation of appropriate water management techniques. Suitable soil moisture increases the biological activities as result of physical and chemical condition of soil improving the crop production finally. Material and Methods: This experiment was conducted under greenhouse conditions in Shushtar city at northern Khuzestan Province using the randomized complete block design using 13 treatments and with 3 replications. Soil samples were taken from a field in the study area, air dried, and passed through a 2 mm sieve. Seven concentration (0, 0.25, 0.5, 0.75, 1.0, 1.25, and 1.5 percentage) of superabsorbent polymers (Aquasorb and Accepta) were used in greenhouse condition. Superabsorbent and 10 Kg soil thoroughly mixed in each pot. All treatments were irrigated when the plants at control showed sign of wilting. There were three replications of each treatment. NPK fertilizers were applied as urea, diammonium phosphate (DAP) and potassium sulphate (K2SO4) based the soil test. Soil samples were again collected which were analyzed for nitrate-N, total organic carbon (TOC), phosphorus and potassium, bulk density, particle density and saturation percentage.NPK of plant samples were also determined. Data were statistically analysed by Duncan test using SPSS. Results and Discussion: Results had shown that the highest bulk density (1.515 gr/cm3) seen in control treatment and with increasing the polymer, bulk density decreased significantly to 0.91 gr/cm3 in treatment No.2. Also the treatments No. 4 and 11 shown decreasing EC significantly from 0.9 in control treatment to 0.68 in No.4. Adding superabsorbent had significant effect on Potassium amount of soil. Using superabsorbent had no significant effect on real density, pH, N amount, Phosphorous, soil organic carbon after yield harvesting in soil and amount of Phosphorous in plant. Significant increasing in number of leaves, branches, fresh weight of plant, and fruit weight with using superabsorbent polymers and the highest used polymer level (treatments No. 7 and 13) had the highest effect on fresh weight of plant which reported 47.2 g for No.7 and 90.47 g for No.13. Also using 1 percentage of Accepta superabsorbent (No.12) caused the significant increasing of fruit weight (502.9 g) instead of control (73.5 g). Based on the presented results No. 2 and 9 had the most effects on N of plants, which the N amount in control was 1.31 percentage and in No.2 and 9 were 2.88 and 2.82 measured respectively. Treatments No. 7, 8, 9, and 11 had the most measured plant potassium. Final results had shown the number of bacteria and fungi increased significantly using superabsorbent and the number of bacteria increased to 215 × 104 in No.13 and the number of fungi to 176500 in each gram of soil. Conclusion: The overall results of this research had shown the promotion of physical, biological, and finally increase the yield as results of using superabsorbent especially Accepta type. Using these superabsorbent polymers in farms need more studies because of more effective climate parameters.
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