Use of tree planter, in general, results in similar tree performance to the use of an auger. Be aware that planting is much much faster with a tree planter. Also, soil amendments must be applied over a wider area if a tree planter is used, i.e. you can't concentrate on the hole itself. Amend the soil to improve growth of the newly planted trees. If you are using an auger, mix the soil to be returned to the hole 50-50 with peat moss or compost.
Fertilizers can harm newly planted trees very easily.
Apply less than 0.1 lb of nitrogen per tree, preferably with a soil drench after the soil has settled. We found that increasing nitrogen resulted in reduced growth in the early years. Mulch can improve early growth and flower bud formation, particularly where soil moisture is limited. Consider using wood chips, since they don't encourage vole activity as much as hay or straw mulch does. Do not wait on establishing irrigation.