I have convinced you to use a Natural Fertiliser, so which one is best?
The type of plant you want to grow will dictate to a certain extent which Fert you can use.
A good general all round Manure is Cow Manure, it is quite balanced as in the NPK ratio is very even with not too much Nitrogen which encourages vigorous growth but not always with any strength.
Cow Manure is "mild" and can be used liberally without to much worry about burning off your plants.
As I have mentioned previously burying any Animal Manure in a trench or hole some time before planting gives the worms a chance to break it down and removes any potential for burning.
Dig the hole and place approx 100-200mm of Manure and fill the hole with water a few times to "activate" the Manure. Leave the hole open for a day then fill it with water once more and place the soil back on top. The objective is that when you place your new plant into the soil the roots don't hit the Manure straight away, it gets a chance to settle down before the roots get to the depth of the now processed Manure.
The effect is always amazing to see, the plant will be just chugging away then it hits the Manure and takes off more often than not about the time of flowering when the first real load comes onto the plant.
Cow Manure is a great all round product that can normally be bought bagged from most Garden Centres or if you are lucky enough to have access to a farm free for the taking.
The Biodynamic system of growing places great emphasis on Cow Manure, it is the number one Preparation used for adding fertility and balance to the soil.
Hope this has been useful.
Be Happy.