The importance of scarification
The benefits of pruning for trees are many: contain growth, regulate the development of grafted plants (in fruit or ornamental trees), promote flowering and fruiting, restore vigor to weak or very old trees, remove branches dead or irregular, maintain the shape of the tree, etc.
The scarification of the lawn can be done:
Manually, using a rake: it consists of vigorously scratching the surface of the earth with the rake. If the area to be scarified is small, it is feasible, but not in a medium or large garden. It is very tiring and inefficient work.
With a scarification machine (Regenerator): This machine has a roller with several vertical knives that cut, break the surface of the soil and destroy this felt, this waterproof layer that suffocates the grass. It also partially breaks the roots, but nothing happens, as they regenerate quickly. The regenerator is used a few times each season (two at most), so it is a good option to use a garden machinery rental establishment. After passing the regenerator, the lawn has a very unsightly appearance, as it looks washed out. We don't have to worry, because in a week or two it will have closed perfectly and will also be regenerated and more vigorous than before. Pass the rake with flexible spikes after scarifying, to collect the "fodder" that the machine has left on the surface. Once either a scarification or an aeration has been done (making holes in the lawn that allow a lot of air to enter), it is convenient to add chemical fertilizers or make a priming. It will be a soil improvement, which your lawn will surely appreciate. A priming consists of spreading, after an aerating or scarification task, over the surface:
Sand alone
Peat or humus alone.
Sand + peat or sand + humus.
If you want, you can also do a light reseeding after scarification.
In summary: EVERY year and on ALL types of lawns it is very convenient to scarify in the spring. Then, once the scarifier or manual rake has passed (if you do it with this tool), it is convenient to add chemical fertilizers or make a mulch with peat or humus. Then, water abundantly and, in a few days, the lawn will be spectacular and rejuvenated. If you can do another scarification in the fall, even better, and if you do an airing in the spring in addition to the "mandatory" scarification, also phenomenal. It is common to see grasslands with little push and with large yellowish spots, mainly due to the compaction of the soil and the felt it has. The solution is to pass the regenerator and then tan.