Application of Gypsum or Sulfuric Acid Improves Physiological Traits and Nutritional Status of Rice in Calcareous Saline-Sodic Soils

This study evaluates the efficacy of applied amendments (gypsum and sulfuric acid, H2SO4) to ameliorate clay loam soil with different salinity and sodicity levels in rice and its adaptation mechanisms in a 3 year (2016-2018) experiment. For this purpose, a lysimeter experiment was conducted in wire-house using soils with mild (ECe =4.1, SAR= 19.86), moderate (ECe =8.0, SAR= 40.47), and severe (ECe = 16.1, SAR= 79.47) salinity and sodicity. Growth and physiological responses of rice were observed under the described salinity-sodicity levels for 3 years. Results revealed that with the intensification in salt stress, crop physiological, nutritional, growth, and yield traits were negatively affected, whereas Na/K ratio was increased with increasing salts stress. Application of amendments significantly improved soil properties, crop growth, and physiological traits of rice under mild, moderate, and severe salinity-sodicity stress. The maximum increase in biological yield of rice was recorded by 55% and 45% with application of H2SO4 at moderate and severe stress whereas, similar to 119% increase in grain yield was observed at severe stress with the same amendment when compared to their respective controls. Although gypsum played an important role in improving plant nitrogen, phosphorus, and potassium content, however, H2SO4 application significantly reduced pH(s) and improved nutrient availability and uptake in rice. This study suggests that H2SO4 and gypsum could be used as effective reclamation agents in long-run for calcareous saline-sodic soils. Along with the effective mitigation of salinity/sodicity, they also improve the physiological adaptation and productivity of rice.

Automated summary

This study evaluates the efficacy of applied amendments in improving clay loam soil with different salinity and sodicity levels for rice cultivation. The results show that application of amendments significantly improves soil properties, crop growth, and yield, while mitigating the negative effects of salt stress.