When and how is that possible?

Components of the potting soil

Freshness Potting soil consists, among other things, of fresh compost, peat or other fibrous materials, as well as a depot Slow release fertilizer. The earth is loose and crumbly, it has a good stability of its structure. This is important so that the cultivated plants can find a hold and do not fall over at the slightest gust of wind.
For water storage are in addition to the fibers also Clay granules or Perlite(€ 35.50 at Amazon *) (Granules made from volcanic glass). Additions of sand make the soil permeable, so that no waterlogging can occur.

The used potting soil

If plants have already been cultivated in the earth for a season, the earth is collapsed and solid. You lack nutrients, the fertilizer depot has been used up. If the soil is used for another planting in this state, the roots will not get enough oxygen and they will no longer be able to supply the plant with food.

Therefore, a used potting soil must be prepared in any case.
It is best to use the following options:

• by machining with Digging fork or hoe the earth well aerate and loosen
• Work in compost or good garden soil
• Bark humus and wool fertilizer also ensure ventilation
• in the garden bed or planter the soil can be filled with green manure ( Phacelia, Mustard seeds, lupine), which is submerged in spring
• new slow release fertilizer in the form of Horn shavings,(€ 32.93 at Amazon *) Incorporate sheep wool or horse manure pellet tests, he cares for the soil life
• to pure nitrogen fertilizers like Horn meal always add one or two handfuls of compost

Depending on which plants are to be cultivated in the prepared soil, the addition of fertilizer must be individually tailored:

• Low eaters such as radishes and peas require little or no new fertilizer
• for medium consumers like carrots and spinach you add a handful of fertilizer to 20 liters of soil
• Heavy eaters like potatoes and tomatoes need two handfuls of fertilizer in 20 liters of soil

If the potting soil is too drained, completely stuck together and heavy with non-drained water, it does not have to be thrown in the trash. It goes to the compost heap and is renewed there by the organisms in the soil.