NOVELTY - Preparing fertilizer using incinerated straw or alkaline wastewater, by adding concentrated acid solution drop-wise to straw, stirring mixture, adding and mixing charcoal, wastewater, plant straw, rice hull ash, alkali to mixed materials, neutralizing final pH of the mixture, cooling reaction product, neutralizing final pH of product, spraying mixed acid solution on back side of reaction mixture, sieving mixture, removing metals and drying mixture.    USE - The method is useful for preparing fertilizer used for adjusting or loosening soil using incinerated straw or alkaline wastewater, as a source of nitrogen, phosphorus and potassium for plants, improving saline-alkali soil compaction, and production of fruits and vegetables (claimed).    ADVANTAGE - The fertilizer can be used both in combination with livestock and poultry manure and nitrogen-phosphorus-potassium based fertilizer composition. The fertilizer improves yield of grains, vegetables and fruits. The method effectively recycles waste resources, and can be effectively stacks or buried inside landfill for preventing groundwater pollution and removing heavy metals chosen from lead, cadmium, mercury, chromium, nickel, manganese, copper and arsenic.    DETAILED DESCRIPTION - Method for preparing soil adjusting or loosening fertilizer using incinerated straw or alkaline wastewater, involves mixing one or more acids chosen from 50-86% industrial phosphoric acid, 30-98% industrial sulfuric acid and 10-98% industrial nitric acid with water to obtain 0.35-50% concentrated acid solution or 80-98% mixed solution, adding 0.35-8% concentrated aqueous acid solution drop-wise under metering pump control to straw in a reactor, allowing the straw to pass through spiral conveyer to cooling jacket, stirring mixture in the reactor at 20-30 revolutions per minute, adding and mixing charcoal, wastewater, plant straw, rice hull ash, alkali preferably potassium carbonate to mixed materials, allowing chemical reaction to occur, neutralizing final pH value of the mixture to 6-9 to obtain soil loosening fertilizer comprising potassium sulfate, potassium phosphate, potassium nitrate, potassium dihydrogen phosphate, potassium hydrogen phosphate, calcium nitrate, magnesium nitrate, calcium phosphate, magnesium phosphate, calcium hydrophosphate, monocalcium phosphate, magnesium hydrogen phosphate, magnesium dihydrogen phosphate, calcium sulfate and magnesium sulfate, cooling the reaction product, neutralizing final pH of the product to 9-14, spraying mixed acid solution on back side of the reaction mixture, sieving the mixture through 10-60 mesh size sieve, removing metals, maintaining the reactor at 180-260 degrees C and drying mixture until water content in the mixture reduces and pH value reaches 6-9 water to obtain the fertilizer.