Research On The Effect Of Water Absorbent Polymer On Soil Physio-Chemical Properties

Drought is a major constrained factor in agricultural development and in particular, drought and the shortage of water resource are the key main conditioned factors in the development of agriculture in the northern China. Chemical water-saving technique is one of high technology used in anti-drought and water-saving in the agriculture. Super Absorbent Polymers (SAP) is one of the important chemical agents and has been widely used in chemical water-saving technology. In this paper, for the basic problem of SAP applications in the agricultural, study on the influence change of SAP character and soil physio-chemical properties which take place in SAP long-term use. Mainly about: the fundamental character of SAP; the influence factors about re-swelling characteristics of SAP; the influence of soil physio-chemical properties with SAP. Comparison the effect about above-mentioned in different use amount of SAP, compartmentalize reasonable use amount of SAP. The results were as following:1. Compared with distilled water, the first water absorption rate in tap water and soil extract is more close to the actual situation. It can be used in reference about first water absorption ability for actual use. When temperature constant, release water rate of SAP was depended on water absorption rate and unite time release water rate. Unite time release water rate is inversely proportional to the granule size of SAP.2.In the process of re-swelling with SAP completely air dry. The re-swelling of SAP was not affected by temperature factor. The re-swelling of SAP was affected by salt ions which depend on the concentration and activity of salt ions. Ion of the salt solution impact on the re-swelling of SAP is mainly embodied in its first water absorption rate. The solution of the salt ions on the impact of SAP is immediate and direct impact. The influence of SAP re-swelling in soil environment is different with solution. Soil environment impact on the re-swelling of SAP is mainly embodied in its second water absorption rate. The soil environment on the impact of SAP is more slowly. In repeated use, salt ions interfere with SAP were counteracted by two parts: stimulus-controlled——resistance ability of salt ions interfere with SAP in the first time, tolerance——resistance ability of salt ions interfere with SAP in the long-term.3. Comparative swelling——air dry——swelling and swelling——half air dry——swelling two re-swelling mode, when SAP not completely dry, The re-swelling of SAP was better than SAP completely air dry. The second water absorption rate can reach the initial water rate of more than 70%, when re-swelling took place in the SAP water content not less than 20%. Although more than 90% of the water which absorbed by SAP can be absorbed and used by crops, but for more economical and reasonable use of SAP, soil moisture should ensure in a certain level. For four kinds of tested SAP, irrigation water to more reasonable when the soil moisture content is greater than 30%. Increase SAP amount too much will lead to SAP water content too low when the soil moisture content in high level, thus affecting the life of SAP, reducing the economic benefits of using SAP.4. Used of SAP in soil is a process mutual influence about SAP and soil environment. The initial use of SAP, the soil physical and chemical properties has been greatly improved, with the increase in the use of the time, SAP's use of the effect of di分钟ishing, resulting in SAP soil physical and chemical properties of the beneficial effects of decreasing. As the main impact, the fundamental character of SAP such as expansion of water is the basis of to improve soil physical and chemical properties.5. To increase SAP amount is a buffer about the impact of SAP by external factors, in a certain period of time to ensure that the use of the effect of SAP, in order to ensure the physical and chemical properties of soil improvement that made by SAP. With time and repeated use of SAP increase, the influence of increase the SAP amount in the gradual lowering. In this study, after SAP re-swelling three times later, SAP's amount can not affect the water absorption rate of SAP in the soil. Compare with four test set amount of SAP, in 0.1% ~ 0.2% of use amount is more economical and reasonable.