Abstract
Abstract: In recent years, the fertility of cultivated land in China has declined significantly due to excessive reclamation. As a result, chemical fertilizer is widely used to increase the fertility of the soil. However, the excessive use of chemical fertilizer results in many side effects such as soil pollution, water pollution and waste of resources. Therefore, it is necessary to develop a kind of environmentally friendly chemical fertilizer and its preparation method.China has a large number of biomass resources. For example, the crop straw produces as many as 700 million tons each year. With the enhancement of environmental protection consciousness and development of biomass thermo-chemical conversion technology, the biomass resources are widely used in the preparation of biomass biochar, bio-oil and gas. Biochar is the solid product of pyrolysis obtained from crop straw and other biomass materials under the restriction or absence of oxygen conditions. Scientific and rational application of biochar in soil is beneficial for increasing the soil fertility, because it can not only compensate for the consumption of soil organic matter, but it also improves the soil pH value and further increases the production of crops.Carbon based fertilizer, which is a new compound fertilizer mixed by biomass carbon and other fertilizers, has been regarded as one of the most effective methods for the application of biochar in soil. With rich pore structure, carbon based fertilizer can increase the soil fertility, improve venting capability, and slow down the release rate of fertilizer, etc.The present studies of carbon based fertilizers focus on the mixture of biochar and a base fertilizer applied into the soil without granulation molding. However, this cannot be industrialized because of the limitation of transportation, storage and other aspects. Moreover, adhesive is required in granulation molding, which will corrode equipment, complicate the production process, increase economic investment, and bring about side effects to the soil such as soil caking, if it is applied over a long term.In this study, a new preparation method for carbon based fertilizer was proposed. Urea, calcium superphosphate, diammonium phosphate and kalium chloratum were used as the basic fertilizer to provide N, P, K. According to the national standard of compound fertilizer material, straw charcoal, urea, calcium superphosphate, diammonium phosphate potassium chloride and a certain amount of water, were mixed together to form granulation without adding any adhesive. The product was granulated with an extruder at room temperature and dried at 50 °C for 4 hours. Finally, the performance indicators of the fertilizer were measured according to the corresponding standards, such as nutrients, moisture content, strength, water solubility, and release effects. The results showed that the formed carbon based fertilizer preferred formula was: 16.64% straw carbon, 70.36% based fertilizer, N: P2O5: K2O=10:8:10. Without adding any adhesives, the performance indicators of molding carbon based fertilizers after drying were as follows: mass fraction of Nitrogen is 10.07%, mass fraction of water soluble phosphorus is 5.47%, mass fraction of phosphorus is 8.38%, water soluble phosphorus accounting for 65.27% of total phosphorus, mass fraction of kalium is 10.45%, water content is 3.24%, strength is 85%, and the pH value is 6.41. These performance results met the relevant national standards. The design of the process is simple and feasible, and provides a reference for the industrial production of carbon based fertilizers.
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