Use of mixed solid waste as a soil amendment for saline-sodic soil remediation and oat seedling growth improvement.

Abstract

Soil salinization has become a worldwide problem that imposes restrictions on crop production and food quality. This study utilizes a soil column experiment to address the potential of using mixed solid waste (vinegar residue, fly ash, and sewage sludge) as soil amendment to ameliorate saline-sodic soil and enhance crop growth. Mixed solid waste with vinegar residue content ranging from 60-90%, sewage sludge of 8.7-30%, and fly ash of 1.3-10% was added to saline-sodic soil (electrical conductivity (EC1:5)=1.83dSm-1, sodium adsorption ratio (SAR1:5)=129.3 (mmolc L-1)1/2, pH=9.73) at rates of 0 (control), 130, 260, and 650kgha-1. Results showed that the application of waste amendment significantly reduced SAR, while increasing soil soluble K+, Ca2+, and Mg2+, at a dose of 650kgha-1. The wet stability of macro-aggregates (>1mm) was improved 90.7-133.7% when the application rate of amendment was greater than 260kgha-1. The application of this amendment significantly reduced soil pH. Germination rates and plant heights of oats were improved with the increasing rate of application. There was a positive correlation between the percentage of vinegar residue and the K/Na ratio in the soil solutions and roots. These findings suggest that applying a mixed waste amendment (vinegar residue, fly ash, and sewage sludge) could be a cost-effective method for the reclamation of saline-sodic soil and the improvement of the growth of salt-tolerant plants.