AMs and abiotic stress tolerance another widely perused area of research.

soil pollution part of soil science so, it's already important 

http://www.tandfonline.com/doi/abs/10.1080/03650340.2016.1154542?journalCode=gags20

You may look on contamination and integration of nanoparticle in soil composite. To best of my knowledge, that is interesting area and still many people working on that

Biochar, most exciting prospect.. and popular area of research as well

Many journals have a page on their websites where papers that have generated the most recent interest are listed, which gives a good feel for areas of research that are very topical.  As a couple of examples - http://www.publish.csiro.au/sr#MostRead;

https://dl.sciencesocieties.org/publications/jeq/most-cited.

You may use Scopus to search the most recent research on soil science or soil pollution. Review papers are useful too. Good luck!

AMs and abiotic stress tolerance another widely perused area of research.

Role of  soil microorganisms in plant nutrition and nutrient availability. Relationship between soil stress and water stress effects on plant growth and early flowering.

Good, you can visit soil science society of Nigeria (SSSN) website or that of America