Environment-friendly composite water retention agent, preparation and using method thereof

The invention discloses an environment-friendly composite water retention agent which comprises loess absorbing an inorganic fertilizer, plant waste, dry animal waste and an acrylic polymer, wherein the loess absorbing the inorganic fertilizer, the plant waste and the dry animal waste are dispersed in the acrylic polymer, and the acrylic polymer is firstly pre-polymerized and then added with nutritional ingredients to be mixed, so that various nutritional ingredients can be prevented from participating into polymerization crosslinking reaction of crylic acid, and the original nutritional ingredients are kept. Meanwhile, nutritional ingredients are uniformly dispersed into the acrylic polymer to be combined into a whole without separation, so that the composite water retention agent is more convenient to use, and enough nutritional ingredients required for growth are uniformly provided to the plant while water retention is achieved. The environment-friendly composite water retention agent is characterized in t