Effect of straw and polyacrylamide on the stability of land/water ecotone soil and the field implementation

• The soil nutrients and soil structure were used to evaluate the stability of the special land/water ecotone soil.
• We found the benefits of the complex which is a mixed application with 3 g/kg of straw and 1 g/kg of PAM through the indoor experiment.
• The measure above proved to be beneficial to land/water ecotone in engineering.
• The mechanism for the effect of straw and PAM on available nutrients, structure and aggregate stability is proposed.

Poor stability of land/water ecotone (L/WE) soil is a serious and increasing problem in the context of ecological restoration. Effective management by adding straw and polyacrylamide (PAM), i.e., SPAM, to soil may increase soil stability, including structure and fertility. Thus, it is important to explore the effects of SPAM on L/WE soil, as well as to determine the appropriate ratio of straw and PAM to achieve optimal increases. To investigate the soil properties and provide basis for ecological restoration, an indoor soil culture experiment, including nine straw and PAM combinations, was conducted. It was found that 3 g/kg straw with 1 g/kg PAM was optimal; thus, this scale was applied in engineering of Gonghu L/WE, which was turning Fishery to Lake. The survey explored changes in soil nutrients and structure, dry-sieved aggregate stability, and wet-sieved water aggregate stability under nine measures. Results indicated that the measurement of SPAM strongly affected soil properties, such as improvements in the fine sand and clay fraction, decreased coarse sand fraction and density, and enhanced content of the larger aggregates (>2 mm), organic matter (OM), available nitrogen (AN), available phosphorus (AP), and available potassium (AK). For soil nutrients, applying of Straw/PAM significantly improved the contents of OM/AN, respectively; showing an increasing trend with a dosage rate. Meanwhile, it was shown that SPAM was more effective than treating each individual component on AP and AK improvements. Regarding soil structure, application of PAM significantly increased contents of the dry-sieved aggregates and wet-sieved water-stable aggregates, especially aggregates >2 mm. Straw mulching only improved the content of dry-sieve medium size aggregates. However, when combining SPAM, the straw improved the medium particle size fraction, after which PAM converted a portion of the medium particles into >2.0 mm aggregates. Furthermore, the measure proved to be beneficial to land/water ecotone engineering.

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