The invention discloses a special coloring agent of a
diammonium phosphate compound
fertilizer, comprising the following constituents: 40-50 parts of
humic acid salt, 0.1-3 parts of carbon
soot, 2-4 parts of acid black, 1-2 parts of acid brilliant scarlet, 0.2-1 part of
sodium hexametaphosphate, and 40-56.7 parts of water by weight parts; the preparation process is that: the material is prepared by weight parts, water is added in a vertical round reaction tank, and then the
humic acid salt, the carbon
soot, the acid black and the acid brilliant scarlet are added and are stirred uniformly, andthen
sodium hexametaphosphate is added, the mixture is stirred continuously and uniformly, so as to obtain the special coloring agent of the
diammonium phosphate compound
fertilizer; the invention solves the problems that the
diammonium phosphate particles produced under an acid
slurry condition are easy to decolorize and the
chromaticity is unstable; the special coloring agent of the diammonium
phosphate compound
fertilizer is green and environmental-protection, has no
pollution and is beneficial to the growth of crops; the product is in a
liquid state and transported closely, and has convenient usage; the
raw material is cheap and easy to obtain, the cost is low and the economic benefit is good.