NOVELTY - Selenium-enriched slow release composite fertilizer, comprises e.g. 1250-2000 meshes diatomite (10-15 pts. wt.); urea (20-25 pts. wt.); ammonium dihydrogen phosphate (10-12 pts. wt.); zinc sulfate (2-4 pts. wt.); tricalcium phosphate (6-8 pts. wt.); potassium chloride (10-12 pts. wt.); dry pig manure (18-22 pts. wt.); soybean dreg (15-17 pts. wt.); polyacrylamide (4-5 pts. wt.); ammonium bicarbonate (0.1-0.2 pts. wt.); selenium yeast (2-4 pts. wt.); dodecyl dimethyl benzyl ammonium chloride (1-2 pts. wt.); zinc gluconate (2-4 pts. wt.); and auxiliary agent (4-5 pts. wt.).    USE - As selenium-enriched slow release composite fertilizer (claimed) used for improving the growth of crops.    ADVANTAGE - The slow-releasing fertilizer has low cost; is efficient; and provides environmental protection. The fertilizer raw material has wide source; is rich in nutrients; the nutrient is not easy to lose from soil and the fertilizer effect is more durable in the soil. It increases the content of selenium in crops and fruits, and also increases economic value of melon and fruits.    DETAILED DESCRIPTION - Selenium-enriched slow release composite fertilizer, comprises: 1250-2000 meshes diatomite (10-15 pts. wt.); urea (20-25 pts. wt.); ammonium dihydrogen phosphate (10-12 pts. wt.); zinc sulfate (2-4 pts. wt.); tricalcium phosphate (6-8 pts. wt.); potassium chloride (10-12 pts. wt.); dry pig manure (18-22 pts. wt.); soybean dreg (15-17 pts. wt.); soybean straw powder (10-12 pts. wt.); tung seed cake (10-12 pts. wt.); plantain (4-6 pts. wt.); water hyacinth powder (3-5 pts. wt.); carboxymethyl cellulose (10-12 pts. wt.); polyacrylamide (4-5 pts. wt.); ammonium bicarbonate (0.1-0.2 pts. wt.); camphor (0.2-0.3 pts. wt.); selenium yeast (2-4 pts. wt.); dodecyl dimethyl benzyl ammonium chloride (1-2 pts. wt.); nano-carbon (2-3 pts. wt.); zinc gluconate (2-4 pts. wt.); vinegar (6-8 pts. wt.); and auxiliary agent (4-5 pts. wt.). The auxiliary agent comprises: poultry feather (15-18 pts. wt.); vinegar (20-25 pts. wt.); copper citrate (1-2 pts. wt.); manganese citrate (1-2 pts. wt.); nano-carbon (1-2 pts. wt.); hydroxyapatite (6-8 pts. wt.); and common andrographis herb water extract (4-5 pts. wt.). Preparation of the auxiliary agent involves high temperature sterilizing of the poultry feather, disinfecting, followed by crushing, adding in edible vinegar solution, and heating to 50-60 degrees C, hydrolyzing for 5-6 hours, adding copper and manganese citrates, nano-carbon, stirring for 15-20 minutes, then adding hydroxyapatite, common andrographis herb water extract, stirring, and dispersing 40-50 minutes to obtain the finished product. An INDEPENDENT CLAIM is included for a method for preparing the selenium-enriched fertilizer, involving: 1) taking water and diatomite in equal parts by weight, mixing, and grinding for 20-30 minutes to form a slurry, stirring the slurry, adding vinegar and zinc gluconate, stirring for 15 minutes, then adding nano-carbon, stirring, and drying to prepare diatomite coating material; 2) mixing the dry pig manure, soybean dreg, soybean straw powder, and seed cake with selenium yeast, adding proper amount of water, mixing uniformly, conducting fermentation until it is completely decomposed; 3) mixing carboxymethyl cellulose, and polyacrylamide, adding proper amount of deionized water, stirring to completely dissolve, followed by adding plantain leaf, ammonium hydrogen carbonate, stirring for 20-30 minutes, mixing with sustained-released agent; 4) mixing the remaining materials and materials from step (1) and (2) uniformly, putting into granulator, granulating, spraying on a surface made in step (3), coating with sustained release coating agent, drying and cooling to room temperature.