It is very common in urban setting that the top soil to be removed or compacted during construction, renovation or during landscape projects which results nutrients being washed away, poor aeration, impenetrable surfaces and also reduce water holding capacity. Another reason why soil is lacking of nutrients is the fact that the nutrient cycle is disrupted when we annually rake of all the leaves and compost them.
The most common method of fertilizing the trees is general broadcast of the granular fertilizers. Generally it goes on the top of the grass. The downfall of this method is that it tends to feed grass roots before it actually gets to the tree roots. Another technique which is common to the homeowner is fertilizer spikes. In this method, the spikes are pushed in to the ground and it is very concentrated amount of fertilizer in one spot and the roots actually have to go to that site to get the nutrients.