There are several approaches for fertilization. Many people provide the plants with fertilisers without taking into account the soil richness. My approach is different. I practise low-yielding dry farming and I do not like spending money if I have no reason for it. I only apply fertilisers when the soil has a clear limiting nutrient. In order to know that, I carry out soil tests. The results show that most of my fields are fertile enough and do not require fertilization.
One of the orchards that I manage is located in an excellent field. The soil is alluvial with good structure, water retention and drainage. The test has shown an interesting fact that will make it easy to get the most out of this land: Everything is fine, but phosphorus.
Phosphorus is a key macronutrient for plant development and fruit quality. Plants can only uptake certain forms of phosphorus, which are stable at neutral pH. At high pH, it becomes unavailable because it is fixed as calcium phosphate. This is exactly the case of this soil; the addition of abundant phosphorus would not solve the problem and money would be wasted. The fertilization plan is cheap and simple: adding small quantities of localised phosphorus every year.
The ideal fertilizer to apply would have been Triple Superphospate (TSP), but it is not always possible to buy the fertilizer that best suit your needs. In the local stores I found a compound fertilizer that contains mainly Phosphorus: 8-24-8. In order to keep phosphorus avalible to the roots and prevent blocking in the soil, I applied it mixed with organic substrate in holes 10 cm deep and 50 cm long, digged by a hoe in the middle of the streets.
I applied 400 g of 8-24-8 compound fertiliser and 1 litre of organic compost per tree in early November. That is approximately the rate of phosphorus recommended by some specialised books. The cost of the fertilization plan is 0,25 € per tree.