Improving agent and improving method for sandy saline-alkali soil

The invention relates to an improver and an improvement method for sandy saline-alkali soil. The improver comprises the following components in parts by weight: 80-120 parts of pine needle mulch, 50-85 parts of acid modified cow dung charcoal, 3-5 parts of zeolite powder, 0.2-0.4 part of an inorganic fertilizer, 2-4 parts of a microbial agent and 2-4 parts of a binding material. The sandy saline-alkali soil improvement method comprises the following steps: S1, excavating sandy saline-alkali soil to be improved, and separately stacking severe saline-alkali soil and mild saline-alkali soil; s2, paving severe saline-alkali soil added with desulfurized gypsum and ferrous sulfate in the excavation area of the sandy saline-alkali soil; s3, paving a salt isolation layer on the paved severe saline-alkali soil; s4, paving a layer of mild saline-alkali soil added with furfural residues on the salt isolation layer to form a buffer layer; and S5, the buffer layer is backfilled with the light saline-alkali soil improved b