What (chemically) does fertiliser do for plants?

Answer 1

Depends on the fertilizer and when you apply it to the plants. Early on in a plants life(vegetative state) you normally use fetilizers with higher levels of Nitrogen. This helps the plant grow stronger and faster and increases its green color. Later on in a plants life (flowering phase) you normally would give it a fertilizer with higher levels of Potassium, to increase flower size and weight. When you see NPK, or N-5, P-1, K-5 on the side of a package of fertilizer, it is giving you the chemical ratio in the fertilizer. Nitrogen 5, Phosphorus 1, Potassium 5. If you do use the stuff remember, you are just supplementing plants with what they are supposed to have, but can't get because its grown inside, outside in a planter, etc. To much fertilizer can result in "burning" a plant. The edges of the leaves will begin to get discolored and flake off of the plant, unless you quickly flush out the excess chemicals. Depending on what your growing you can normally find the proper chemical ratios to give to plants in any gardening book. Trial and error helps too, after a while you will know what a plant needs just by looking at it.

Answer 2

Many fertilisers actually supply nitrates to the soil..

Plants need nitrates to carry out their functions..

Nitrate is a form of nitrogen from the air, which plants use, as they cannot directly use the nitrogen from the air..

Usually plants use bacteria, called 'Nitrogen Fixing Bacteria', which usually converts nitrogen into the air, into nitrates

Answer 3

Provides necessary chemicals (nutrients) in a pure form.

Kinda like vitamins.

Answer 4

Supplies nutrients that should be in the soil but are lacking due to previous planting, or the type of soil.