NOVELTY - Super absorbent polymer fertilizer containing nitrogen is obtained by pulverizing maize straw to obtain powder, mixing powder with chloroacetic acid, filtering the stirred mixture, drying the filtrate to obtain modified powder, dissolving the powder in water, performing ultrasonic processing the mixture to form modified cellulose solution, adding cerium ammonium nitrate and nitrous acid into the solution, performing ultrasonic processing to obtain mixed solution, drying the solution into gel and immersing the gel in urea or liquid urea to obtain product.    USE - The super absorbent polymer fertilizer is useful for improving the growth of crops.    ADVANTAGE - The raw material is cost-effective and environmentally-friendly. The method can be performed simply and rapidly.    DETAILED DESCRIPTION - Super absorbent polymer fertilizer containing nitrogen is obtained by pulverizing the maize straw to obtain powder, mixing the powder with chloroacetic acid and ethanol, stirring the mixture at 60-80 degrees C, washing and filtering the stirred mixture using ethanol solution, drying the filtrate to obtain modified powder, dissolving the powder in water, performing ultrasonic processing the mixture for 4-7 minutes to form modified cellulose solution, adding cerium ammonium nitrate and nitrous acid which are dissolved in water into the solution, performing ultrasonic processing for 1-2 minutes to obtain mixed solution, adding potassium persulfate solution into the mixed solution, drying the solution into gel and immersing the gel in urea or mixing the gel in liquid urea to obtain product. An INDEPENDENT CLAIM is included for method for preparing super absorbent polymer fertilizer, which involves pulverizing the maize straw using mesh size of 80-200 to obtain powder, mixing (in parts weight) powder (10-50) with ethanol (100-200) and 50% sodium hydroxide deionized water (20-100), stirring the mixture at 25-40 degrees C for 1-2 hours, adding chloroacetic acid (15-70) and ethanol (45) to the mixture, stirring the mixture at 60-80 degrees C for 1-2 hours, washing and filtering the stirred mixture using 80-90% ethanol solution, drying the mixture to obtain modified powder, extracting two fraction of modified powder, performing ultrasonic processing for 4-7 minutes to form the modified cellulose solution, dissolving the solution in cerium ammonium nitrate (0.1-0.2) and nitrous acid (0.225-0.64), extracting the solution (15-40) and N, N-methylene-bisacrylamide (0.045-0.225), adding the solution into the modified cellulose solution, performing ultrasonic processing for 1-2 minutes, adding potassium persulfate (4) into the mixed solution, reacting the solution in oven at 60-100 degrees C for 30-60 minutes until to obtain gel, soaking the gel in solution for 7-12 hours or directly adding liquid urea to the gel and drying the gel in oven at 640-700 degrees C to obtain product.