Long-term rice cultivation enhances root development and yields by improving the structural properties of soil aggregates in saline–alkaline environments

Rice cultivation has the ability to improve saline soils. However, the effects of long-term rice cultivation on saline soil chemistry, salt ions, root characteristics, and aggregate formation remain unclear. In this study, the impact of different planting durations (1, 3, 5, 8, and 10 years) on the spatial and temporal transport of soil salts, soil chemical properties, distribution and stability of aggregates, root characteristics, and yields, were assessed. Long-term rice cultivation reduced soil pH, exchangeable sodium percentage (ESP), and EC in the 0-60 cm soil layer compared to 1Y (5.45%, 61.57%, and 81.87% reduction in topsoil (0-20 cm) and 8.54%, 72.82%, and 71.94 in subsoil (20-60 cm), respectively). However, the soil organic matter (OM), alkaline nitrogen (AN), phosphorus (AP), and potassium (AK) increased (217.09%, 90.18%, 89.23%, and 179.18% increase in topsoil and 223.72%, 81.24%, 174.28%, and 172.57% increase in subsoil, respectively). Additionally, the Cl - , K + , and Na + in the soil gradually leached downward with the increase in the duration of rice cultivation (55.87%、36.08%、59.80%). Simultaneously, the increased duration markedly elevated the soil macroaggregate content (11.43%-20.04% by dry-sieving and 53.48%-288.09% by wet-sieving), clayey grain content (59.17%-198.33%), and soil aggregate stability, especially for 8Y and 10Y. The improved soil structure and root characteristic under long-term rice cultivation conditions increased the yield (28.89-54.81%). Partial least squares path model displayed that rice cultivation affected the aggregate stability, root characteristics, and rice yield via the corresponding chemical properties (pH, EC, and ESP), nutrient contents (AN, AP, AK, and SOM), and salt ion contents (Cl - , K + , and Na + ). These findings are critical to understanding aggregate formation in saline soils. Enhancing rice root growth and crop yield by reducing soil salinity factors and increasing soil nutrients improves soil aggregate characteristics over the years of rice cultivation in saline-sodic soils. • Long-term rice cultivation decreased soil salinity, increased the content of nutrients • Long-term rice cultivation significantly increased soil macroaggregates and aggregate stability, while also promoting the transition from sand grains to clay and silt. • Salinity factor is the main driver of soil aggregate stability. • The negative effect of high saline factor on root characteristics was critical for limiting rice yield in saline-sodic paddy fields.