GROWING TREES IN A GARDEN - The influence of plants on a soil.

Mr. Firman lives in a family house surrounded by a large garden that he cares for. In one part he grows vegetable and fruit, in other part there are fruit trees, and in the back there are old broad-leaved trees and some conifers. While he was reconstructing the front fence, Mr. Firman decided to make a hedge and with spruces. These trees are quite cheap and grow fast. In a half year it was obvious that spruces do not thrive, although they are watered additionally. In the backyard there are lot of trees with no sign of suffering, so why do the spruces grow badly? It must be in the soil, thinks Mr. Firman, but he does not know how to prove it.

Will you help Mr. Firman to solve the problem? Try to find out whether there is a relation between acidity/basicity of plants and soil.