Effects of a super-absorbent polymer derived from poly-γ-glutamic acid on water infiltration, field water capacity, soil evaporation, and soil water-stable aggregates

ABSTRACT

The poly-γ-glutamic acid super-absorbent polymer (γ-PGA SAP) is an environmentally friendly material. Five different γ-PGA SAPs contents based on weight, including 0% (CK), 0.05% (T1), 0.10% (T2), 0.15% (T3), and 0.20% (T4), were added to the soil in this study. The results showed that cumulative infiltration decreased by 32.4% (T1), 39.2% (T2), 51.0% (T3), and 52.0% (T4) at 90 min and the field capacity was increased by 18.7% (T1), 26.0% (T2), 37.8% (T3), and 58.3% (T4) compared with the CK. The cumulative evaporation of the different treatments with γ-PGA SAPs was 17.1% (T1), 23.5% (T2), 24.4% (T3), and 25.3% (T4) higher than that of the CK at the end of the evaporation experiment. The evaporation experiment lasted 96 h (CK), 132 h (T1), 144 h (T2), 180 h (T3), and 312 h (T4) to progress from field capacity to a soil water content of 10%. Adding γ-PGA SAPs to the soil significantly increase the water-stable aggregate content below 0.25 mm when the γ-PGA SAP addition exceeded 0.10%. So reasonable utilization of γ-PGA SAP can improve water use efficiency and improve soil structure in semi-arid areas.

KEYWORDS:

• Poly-γ-glutamic acid super absorbent polymer
• soil water infiltration
• field capacity
• evaporation
• water-stable aggregate

Acknowledgements

This project was supported by the National Natural Science Foundation of China (51379173), Natural Science Basic Research Plan in Shaanxi Province of China (Program No. 2018JM5051). Thanks Mr. Lei Ge of Institute of Land Engineering and Technology, Shaanxi for his excellent technical guidance in the field of environmental scanning electron microscopy.

Disclosure statement

No potential conflict of interest was reported by the authors.

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Funding

This work was supported by the National Natural Science Foundation of China [51379173]; Natural Science Basic Research Plan in Shaanxi Province of China [2018JM5051].