Hi all, I am in the process of planning native shrub beds for a client and am working in a large open grass field in Surrey, B.C.. The soil is heavily compacted, has a very thin layer of top soil, and drains quite slowly (appears to be somewhere between a clay loam and silty clay loam). My question is should I add a soil amender and till it in? or just add a top soil? Also should I loosen up the existing soil first with a backhoe? Any advice is appreciated.