摘要
The Songnen Plain in Northeast China is a global hotspot for soda saline-alkalization. This region suffers from severe water security challenges that limit agricultural productivity. Our assessment reveals severe irrigation hazards in the local saline-alkaline water. These waters show prevalent alkaline conditions with pH values ranging from 8.04 to 9.50. The dominant water type is NaHCO3, with extreme sodicity levels. Importantly, 63.3% of water samples were classified as C4S4 (EC > 2250 & micro;S cm(-1), SAR > 26), indicating extreme hazard. These samples exceeded sodium hazard thresholds by 2.3-4.8 times. Hydrochemical analysis identified silicate weathering, cation exchange, and evaporative concentration as key processes driving water quality deterioration. Importantly, rice-crab co-culture systems, particularly with juvenile crabs, effectively transform these constraints into opportunities for sustainable agriculture. The juvenile crab system achieved comprehensive improvements, reducing SAR by 41.25%, alkalinity by 1.21 mmol/L, and sodicity (%Na+ = 58.05), while increasing rice yields by 10.61% and total economic output by 84.51% compared to rice monoculture. A key finding was the consistent association between crab activity and concurrent RSC increases with sodium leaching, providing a new perspective on interpreting water quality indices in integrated systems. Our findings establish rice-juvenile crab co-culture as an effective nature-based solution that simultaneously addresses water security and agricultural productivity in soda saline-alkaline regions.