Leaching of salt-affected soil amended by leonardite

Salt-affected soils are widely distributed in arable croplands worldwide with potential productivity so that it is important to develop and utilize these soils. This study investigated the effects of leonardite at the application dosage of 0 (CK), 1% (T1), 3% (T2), and 5% (T3) on amending salt-affected soils under intermittent leaching. Results showed that leaching effectively reduced the electrical conductivity (EC) in soil at CK/T1/T2/T3 with 67.4%/70.9%/75.7%/75.6% of salt discharged. As the dominant cation in leachates, Na+ removed accounted for 75.1% (CK), 79.7% (T1), 72.6% (T2), and 71.5% (T3) of the total cation in soil. Sodium adsorption ratio of soil column for CK/T1/T2/T3 treatment decreased by 61.1%/68.1%/50.0%/44.9%. Organic matters in the soil reached 9.74/17.20/31.41/42.88 g/kg for CK/T1/T2/T3 treatment at the end of the experiment, indicating a fertile prospect for reclamation of the salt-affected soils. Soil pH increased with leonardite dosage after leaching in a similar pattern as the decline of EC. The results would provide practical assistance for amending salt-affected soil in the Yellow River Delta.

Automated summary

The study found that under intermittent leaching conditions, application of leonardite can effectively reduce the electrical conductivity and sodium content of salt-affected soils, increase the organic matter content in the soil, and help in the reclamation of salt-affected soils, showing promising application prospects.