TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Method: The method involves crushing the waste stems, branches and leaves of cassava into broken shred having cross section area less than 0.3 cm2, piling the crushed cassava waste on fermentation field, paving one layer of waste having height of 8-12 cm, uniformly scattering one layer of inorganic phosphorus fertilizer and yeast on the waste, paving one layer of waste on the formed layer, and scattering one layer of inorganic phosphorus fertilizer and yeast, repeatedly paving till the waste layer has height of 1.5 m, watering the waste to make the water content of the waste to 50-60%, mixing and pressing the stack with turning machine, standing and fermenting mixture, turning and stirring after temperature reaches 60-70 degrees C, turning once per 3-5 days, and fermenting for 15-25 days, conveying the mixture to drier to dry the waste to make water content of the waste to 10-20%, where the weight of the inorganic phosphorus fertilizer scattered on each layer of the waste is 3-5% of total amount of the crushed waste, and the weight of the yeast is 0.02-0.07% of total weight of the crushed waste, conveying the fermented dry waste to the mixer and mixing with nitrogen, phosphate and potassium fertilizer, where the weight of the nitrogen, phosphate and potassium fertilizer is 50-60% of total weight of the dried waste, crushing the waste to less than 80 meshes, extruding and pelletizing mixture, roll drying mixture at 200-250 degrees C for 10-15 minutes, and packing product. The fermentation field is cement terrace stock dump having a sloping surface of 2-5 degrees , where four sides of the terrace stock dump are provided with cement shallow ridges, one corner of the terrace stock dump is provided with a waste water recycle pool, the waste after seeped from the stacked cassava waste flows to the recycle pool, and the wastewater in the pool is used for regulating humidity of waste stems, branches and leaves of cassava when fermenting. The inorganic nitrogen, phosphate and potassium fertilizer is urea or calcium superphosphate. The yeast is chosen from Candida utilis, C.tropicalis and Saccharomyces cerevisiae. The nitrogen, phosphate and potassium fertilizer is urea, ammonium sulfate, diammonium phosphate, calcium superphosphate, potassium sulfate or potassium chloride. ACTIVITY - Fertilizer.