Why are eggshells and tea dregs harmful to flowers?

In daily life, some people like to buckle egg shells in flowerpots or water flowers with leftover tea, thinking that this will add nutrients to flowers and promote their rapid growth. Buckle the eggshell on the flowerpot, the remaining egg white in the shell will flow into the surface of the pot soil, produce heat after fermentation, and directly burn the roots of the plant. At the same time, egg white fermentation will produce a bad smell, attract flies to maggots, bite the roots, and then easily induce the occurrence of other diseases and insect pests, affecting the normal growth of flowers. The residual tea contains theophylline, caffeine and other alkaloids, which has a relative destructive effect on the organic matter nutrients in the soil, which is not conducive to the growth of potted flowers. at the same time, the residual tea covers the basin, which will gradually ferment mildew and hinder the permeability of the basin soil. cause hypoxia in the basin and directly affect the respiration of the roots. However, after retting, the supernatant of the egg shell is taken as topdressing or the eggshell is baked and crushed and applied into the basin soil, which is beneficial to the growth of flowers. The application of retting tea residue as base fertilizer is also beneficial to the improvement of soil.