Humus technique:
This is done with organic fertilizer of natural origin which contains a series of nutrients that are released gradually, allowing plants to absorb them slowly. It should be done in late winter and in autumn, never in summer. Its properties are:
� Provides soil with nutrients
� Improves the structure of the soil, boosting its ability to retain water
� Aerates without forming a hard crust on the surface

Organic fertilizers are those which come from the decomposition of plant remains, animal manure, mixes of excrement and variable amounts of peat, straw etc. The drawbacks in using humus of this kind are:
� Frequent appearance of allergies
� Weed seeds contained in humus, spread over land and sprout in spring
� Foul odor over prolonged period of time
� The organism responsible for tetanus (Clostridium tetani) grows in animal manure.
��Leishmaniosis, a disease contracted mainly by dogs and humans, is transmitted by a mosquito which carries Leishmania and lays its eggs in animal excrement so larvae will develop there.

These days there are peat-based products which also contain chemical fertilizer, such as Kerdion Delta, which has the advantages of the former but not the drawbacks. They products are a bit more expensive, but they are worth it.

Lawns should be treated with a layer of humus in late winter. Before doing so it is best to eliminate dead grass by scarification and then add a thin layer of humus mixed with sand.

In order to apply organic fertilizer to hedges and bushes, poke lightly in the soil to help introduce the nutrients. These species like worm humus mixed in with the fertilizer.

Young ornamental trees and fruit trees should be fertilized at a certain distance from the trunk because the youngest and most absorbent roots are located at the distance where the branch span ends.

Surface Fertilizing

This is usually applied in spring and early summer.
Mineral and chemical fertilizers contain three main elements: nitrogen, phosphorous and potassium, as well as others in small quantities which are also essential for plant development. They act quickly but do not last as long as organic fertilizers. They should be used in the proper dosages to avoid nutritional imbalances in the plants and burns.

These products may be packaged as colored granules or as powder, both of which should be applied to the soil close to the roots, or as a liquid, diluted in water before being used.

There are fertilizers designed for specific species such as lawns, hydrangeas, rose bushes, conifers, rhododendrons, geraniums etc.

In general, plants need a surface fertilizer when their leaves are yellowing, show sluggish growth and their stems are thin or weak.

Never use the technique when plants are in a vegetative state or about to enter one.

In rainy areas like the north of Spain, or in areas where you must water frequently and the soil has a lot of sand, plants should be fertilized more frequently because the soil is effectively washed clean.

Some gardeners prefer to use natural organic fertilizers; others use only chemical ones. The best results usually come with applying a combination of both, but each in the proper time of year.