Changes in soil quality and crop productivity along rice cultivation chronosequences in saline-alkali soils

Paddy cultivation constitutes a viable bioremediation approach for rehabilitating salinized croplands in the Hetao Plain region of western China. It plays a crucial role in enhancing crop yield, promoting the accumulation of soil organic carbon, and improving overall soil health. However, the impact of changes in rice cultivation chronosequences on the interactions among rice growth characteristics, soil quality index (SQI), and crop yield remains unclear. Thus, a chronosequence field experiment (1, 3, 5, 8, 10year cultivation durations) was established to elucidate the synergistic mechanisms underlying salinized soil amelioration and agricultural productivity enhancement. The results indicated that plant height, stem thickness, and Relative Chlorophyll Content (SPAD) gradually increased, while the net photosynthetic rate (Pn) and maximum photochemical efficiency of PSII Maximum Photochemical Efficiency (Fv/Fm) initially increased and subsequently decreased during rice cultivation. The soil pH, total dissolved salts (TDS), and exchangeable sodium percentage (ESP) in the 0-60 cm soil layer all exhibited a decreasing trend with increasing duration of rice cultivation, with reductions of 0.93 %-10.55 %, 20.5 %-74.0 %, and 11.22 %-81.90 %, respectively. The other planting years increased SQI by an average of 3.5, 1.7, and 0.5 times in the topsoil, subsurface, and subsoil layers, respectively, compared to 1Y. In addition, the yield increased significantly by 28.89 %-54.81 % compared with 1Y. Head rice rate was improved by 50.6 %-146.4 %, while the chalky rate and degree of chalkiness decreased by 55.1-83.0 % and 62.0-86.5 %, respectively. Partial least squares path model (PLSPM) illustrated that soil nutrient accumulation, salinity stress factors, and the reduction of salt ions were the main pathways driving SQI, while SQI had a significant positive effect on rice yield and a notable negative impact on rice quality. Overall, long-term rice cultivation has a positive effect on improving soil quality and crop yield in saline soils.