Super absorbent polymers mitigate drought stress in corn (Zea mays L.) grown under rainfed conditions

Authors: ABDALLAH, AHMED - Damanhour University; MASHAHEET, ALSAYED - Damanhour University; Burkey, Kent

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/24/2021
Publication Date: 8/1/2021
Citation: Abdallah, A., Mashaheet, A., Burkey, K.O. 2021. Super absorbent polymers mitigate drought stress in corn (Zea mays L.) grown under rainfed conditions. Agricultural Water Management. 254:106946. https://doi.org/10.1016/j.agwat.2021.106946.
DOI: https://doi.org/10.1016/j.agwat.2021.106946

Interpretive Summary: Rainfall patterns have become more variable in recent years as a result of climate change, with severe and unpredictable drought and flooding that impact agricultural production. Furthermore, water is becoming a limited resource in many agricultural areas worldwide. Technologies that help retain rainwater in the soil profile will contribute to maintaining soil moisture throughout the growing season and to minimizing the use of irrigation water. In this study, a team of researchers from Egypt and USDA-ARS tested the ability of superabsorbent polymers as a soil amendment to retain rainwater following a rain event for use in supporting plant growth during periods of drought. In both laboratory and field experiments with sandy soil, three superabsorbent polymers (Stockosorb 660, Hydrosource and SuperAB A200) were found to retain significant amounts of water that contributed to enhanced growth of corn under rainfed conditions. The results suggest that superabsorbent polymers represent a viable approach to mitigate drought stress of crops, particularly in humid subtropical climates where there is significant water loss from soil percolation following intense rain events.

Technical Abstract: Under global warming, the rainfall is predicted to become more intense and less frequent, causing waves of summer drought and rainwater loss by deep percolation, resulting in both inefficient use of rainwater and yield reduction. Super absorbent polymers (SAPs) have been studied as soil amendments in arid and semi-arid environments, but little is known about potential use for drought stress mitigation in humid subtropical climates under rainfed conditions. This study investigated the potential of three K-based SAPs (Stockosorb 660, Hydrosource and SuperAB A200) to act as water reservoirs during periods of drought. In the laboratory, SAPs mixed with sandy soil were tested for water absorption capacity (WAC) and re-swelling capacity, saturated hydraulic conductivity (Ks), water holding capacity (WHC) and storage of simulated rainfall. SAPs showed high WAC, re-swelling capacity, reduced Ks and increased soil WHC with performance dependent more on SAPs concentration than SAPs type. The three SAPs effectively reduced rainwater transport and increased soil water storage during simulated rainfall. In North Carolina, USA, a field study with corn in loamy sand soil under rainfed conditions tested the effects of the three SAPs at three concentrations (0.15, 0.30 and 0.45% w/w) on rainwater transport/storage, biomass production, and biomass rainwater use efficiency (WUEbiomass). Under field conditions, 41.76% of rainwater was percolated in the absence of SAPs while in SAPs-amended soil (0.45% w/w) only 4.8, 5.5 and 6.02% was lost by percolation, for Stockosorb 660, Hydrosource and SuperAB A200, respectively. The retained rainwater resulted in higher leaf water potential leading to enhanced plant growth and WUEbiomass. Stockosorb 660 performed best in terms of rainwater saving, while Hydrosource was the most effective in terms of plant growth and WUEbiomass. The results suggest that SAPs soil amendment is a potential approach to mitigate drought stress under rainfed conditions in humid subtropical climates.