3. Backfilling

Before starting to backfill, make sure the root ball is the correct depth.
The top of the root ball should be level with the soil, and under no circumstances should soil be placed over the top off the root ball (Figure 4).

figure4 wFigure 4. Top of root ball should be level with soil
Back filling with sandy soil is generally loose enough, although in heavier soils it will need to be worked over and broken up.
This is so no air pockets are created that could inhibit root growth. Back fill around the tree to about 2/3, lightly tamping the soil only and then water.
Back fill the remaining 1/3 and then water again.

What comes out of the hole is what should be used as back fill, once it has been well worked over. Unless the soil is so bad you have no other choice, always use the existing soil.

Adding organic matter will improve structure (aggregation of soil particles), drainage and fertility in most soils but is not necessary to get a good result when planting a tree.
If you have extremes in soils - for example heavy clay or sandy soils; adding some well composted organic matter may be beneficial. If organic matter is added, it should be no more than 30% and only added to the final 1/3 of back fill. If added it needs to be well mixed through the final 1/3 of back fill before placing into the hole.