Brown Coal itself, has a high cation exchange capacity due to its high content of Humus, therefore increasing the cation exchange capacity of the soil, this in turn reduces the effect of salinity in the soil.
The increased levels of Humus then chelate or bind up the Sodium and soluble salts, whilst these salts are still present in the soil profile they are taken out of contention through a buffering and chelating action, created by the increased Humic levels in the soil and eventually broken down gradually over a longer period of time.
Humic acid is also a sequestering compound which allows it to break the bond between Sodium and Magnesium, therefore allowing the Sodium to leach from the soils profile.
Tests in the North Dakota area by the government research workers showed that Humic acid removed Sodium from the soil, they also found that Humic extracts from lignite increased the population of important Nitrogen fixing bacteria.
Micro organisms in the soil, not only benefit from increased humus levels as a nutrient source, but also from the physical effects resulting in a more favourable soil environment for these populations to flourish. All this helps to reduce the effects of salinity in the soil.
Humus is also the soils reservior of nutrient availability, holding on to nutrients in available forms until the plant requires them. Just as it can hold on to salinity until it can be satisfactorily dispersed or broken down by the many biological actions that take place in healthy soil.