Sodium and potassium interaction in salt-affected lowland rice soils in Balayan, Batangas, Philippines
2024
Bugia, S.A.C.
Climate change, sea level rise, and temperature increases have been found to contribute to degradation of some agricultural lands. Extreme rainfall and typhoons may cause seawater intrusion in coastal agricultural areas with sea level rise. This study aimed to evaluate the changes in soil properties in a selected salt-affected lowland rice area in Balayan, Batangas [Philippines] for two cropping seasons. Total potassium and sodium concentrations in plant tissues and the characteristics of the different water sources in the study area were also determined. Results showed high cation levels and salinity parameters for plots near the swamp which is the source of seawater intrusion during floods and high tides. Plots that are least affected by flooding also showed the highest exchangeable Ca levels in both cropping seasons. The data for soil chemical properties during the wet season showed higher levels than in the dry season, which can be attributed to the extreme rainfall conditions and high tide episodes promoting saltwater intrusion. In addition, the different water sources in swamp water, underground water, and irrigation water, revealed high salinity according to USSL diagram of salinity and sodicity hazard, with the highest concentration of Na sup + cations. It was also shown that the level of exchangeable Na in the plots has positive correlation with the Na:K ratio and total Na sup + concentrations in rice plants, while there is a negative correlation with the Total K concentrations. The correlation analysis for leaf Total Na sup + and K sup + concentrations showed negative interaction between the two cations. Reduction in rice yield was also found to be correlated with EC, exchangeable Na, total Na, and Na:K ratio in the plants.
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