Water-retaining synergistic compound fertilizer and preparation method thereof

The invention discloses water-retaining synergistic compound fertilizer. The water-retaining synergistic compound fertilizer is prepared from the following raw materials in parts by weight: 0.2-0.6 part of nanocarbon, 0.1-0.3 part of gamma-polyglutamic acid, 0.2-0.6 part of carboxymethylcellulose, 6-17 parts of humic acid powder, 25-38 parts of ordinary compound fertilizer, 4-10 parts of montmorillonite, 3-7 parts of acrylic acid, 12-18 parts of xanthan gum, 0.01-0.02 part of cross-linking agent, 0.005-0.01 part of initiator, 6-15 parts of rice husk biomass charcoal, 1-5 parts of concentratedsolution containing bacteria and 5-8 parts of starch adhesive. The invention further provides a preparation method of the water-retaining synergistic compound fertilizer. The water-retaining synergistic compound fertilizer is prepared through three-layer wrapping, envelopes are not needed, preparation is simple, the cost is low, the water-absorbing and water-retaining property is good, multiple controllable release of fer