Question: used land
When repotting a plant, what use can I make of old soil?
Answer: earth used
the new and fresh soil, which I compress in the nursery, is rich in mineral salts, which over time our plants absorb; in particular, each plant, depending on the type, species and size, absorbs a certain type of mineral salts from the soil, rather than others, more or less rapidly. When we change the soil present in a vase, it is because, despite the addition of fertilizer from the outside, this substrate is now exhausted, and therefore does not contain larger quantities of substances such as nitrogen, phosphorus and potassium, or at least does not contain any sufficient quantities or in interesting qualities for our plants.
So we find ourselves with a soil without useful mineral salts, which often however accumulated little useful mineral salts, as happens for the limestone contained in the water of the waterings.
In addition to this it often happens that parasites of various types have developed in the soil, such as mold, fungi or insects, which would be harmful to the plant.
The advantages that it can still show are due more than anything else to the mixture of the soil which, although lacking in mineral salts, can still be soft and permeable.
So, if the plant that was grown in that soil is perfectly healthy, then we can use the exhausted soil to improve the soil mix in the flowerbeds of the garden or vegetable garden, spreading it on the surface and burying it with a hoe; or we can use it to improve the composition of the heap contained in the composter, which often contains too many green scraps.
Or we can mix it with good manure, place it in a corner of the garden, and let it "ripen" until the next year, when we can use it for any purpose. Very often it is useful to add soil of this type to the flowerbeds of the garden or even to the base of the long-standing shrubs, which often suffer due to excessively compact soil.
If the plant contained in it presented diseases of any kind it would be advisable to throw it; if we wish we can try to recover it by letting it dry in sunlight and then composting it.
If the soil is that contained in a small vase, or we are not sure that the plant contained in it is perfectly healthy, then perhaps it is the case to throw it; in the municipalities where waste is collected separately, the soil is often considered a waste to be inserted into the organic bag, and not a green waste. So before throwing it in the wrong bag, ask your municipality how they use the various types of waste and where they think it is more appropriate to insert the soil residues.