| Excessive application of chemical fertilizer not only increases crop yield,but also causes problems such as soil compaction,acidification,nutrient imbalance,and decreased fertility,which not only leads to the waste of nutrient resources but also has a negative impact on the environment.A lot of biomass resources idle in our country are excellent raw materials for the manufacture of biochar and organic fertilizer.Biochar has excellent characteristics such as large surface area,developed pore structure and rich surface functional groups.Organic fertilizer contains a lot of organic matter,which can continuously release nutrients to the soil through slow decomposition.Both can improve soil physical and chemical properties,reduce nutrient leaching and promote crop growth.This paper focuses on biochar based organic fertilizer and takes tomato as the test object.The changes of soil environment and tomato growth and development after application of carbon-based organic fertilizer were analyzed,and the fertilizer efficiency of carbon-based organic fertilizer was evaluated.The results showed that:(1)the change of carbon fertilizer ratio would significantly affect the growth promotion effect of carbonbased organic fertilizer and the soil bulk density.In the range of 0～50%,with the increase of carbon/fertilizer ratio,straw dry weight first increased and then decreased,and soil bulk weight gradually decreased.The growth promotion effect was the best at 30%carbon/fertilizer ratio,and the soil bulk density was the lowest at 50%.Compared with blank treatment and traditional fertilization treatment,straw dry weight increased by 65%and 19%,and soil bulk density decreased by 8.3% and 9.8%,respectively.(2)Carbonbased organic fertilizer(BCOR)can increase soil nutrient content and reduce soil nutrient loss,and the overall effect is better than that of traditional chemical fertilizer(NPK)and single application of biochar(BC)and organic fertilizer(OR).Compared with blank treatment(CK),the content of soil available nutrients and organic matter could be maintained at a higher level at seedling stage,flowering and fruiting stage and early fruiting stage.Compared with traditional chemical fertilizer treatment,the nutrient release amount of charcoal-based organic fertilizer was lower in the early application stage(tomato seedling stage)when tomato nutrient demand was small,while in the middle and late stage(tomato flowering and fruit setting stage and first fruit stage)when tomato nutrient demand was high,the soil nutrient could be kept at a higher level,which could not only ensure the normal growth and development of tomato but also reduce the risk of nutrient loss.(3)Application of carbon-based organic fertilizer could significantly promote the growth and development of tomato,and the overall effect was better than that of traditional chemical fertilizer and single application of biochar and organic fertilizer.Carbon-based organic fertilizer can significantly increase the yield of tomato fruit per mu,compared with blank treatment and traditional fertilizer treatment can increase 97% and 86%,respectively.It could significantly increase the accumulation of N and P nutrients in fruit by 31% to 69%.It can increase the contents of Fe,Mn,Cu and Zn trace elements in fruit by 31% to 108%.The dry weight of tomato straw in BCOR group was 55% and 60% higher than that in blank treatment and traditional fertilization treatment,respectively.In this paper,heavy metal contents in soil,tomato plants and fruits were analyzed,and heavy metal pollution risks and human health risks of carbon-based organic fertilizer were evaluated.The results showed that:(1)Application of carbon-based organic fertilizer could reduce the content of available heavy metals in soil,straw and fruits.Compared with blank treatment,the application of carbon-based organic fertilizer can significantly reduce the soil available Cd concentration by 14%,but there is no significant difference with traditional fertilizer.It could significantly reduce the soil available Cr concentration by 19% and 9%,respectively,compared with blank and traditional fertilization treatments.Compared with blank straw,the concentration of As,Pb and Cr in straw can be significantly reduced,with ranges of 38%,23% and 22%.However,there is no significant difference between the concentration of As and Pb and that of traditional fertilization treatment,and the concentration of Cr has a trend of significant increase.Compared with blank treatment,the concentration of As and Cr in tomato fruits was significantly decreased by 66% and 41%,respectively,and the concentration of Cr was also significantly lower than that of traditional fertilization treatment.(2)Application of carbon-based organic fertilizer can reduce heavy metal pollution of tomato.Compared with the blank treatment,the tomato pollution index and the enrichment index of As and Cr were significantly decreased,and the enrichment index of Cr was also significantly decreased compared with the traditional fertilization treatment.The transfer index of As,Cr and Pb was significantly decreased compared with blank and traditional fertilization treatment,and the transfer index of As and Cr was significantly decreased compared with traditional fertilization treatment.(3)Application of carbon-based organic fertilizer can reduce carcinogenic and non-carcinogenic health risks of tomato fruits,and the effect is better than other fertilization treatments.In this paper,the life cycle evaluation of different fertilization treatments was carried out to analyze the impact of carbon-based organic fertilizer on the environment.The results showed that: the energy consumption of biochar and carbon-based organic fertilizer was negative,and both had energy output.The combined effect of biochar environment was lower than that of traditional fertilization,and carbon-based fertilizer was higher than that of biochar or organic fertilizer alone,but lower than that of organic fertilizer alone.In this paper,a set of carbon-based organic fertilizer molding die is developed.By combining the plunger with the press roll with variable diameter,the friction between the flat die and the press roll can be reduced during rotation,and the power waste and parts wear can be reduced.After mechanical simulation,the strength of the mold is determined to be within the safe range,and the production efficiency of the mold can reach 269 kg/h by calculation.Based on the systematic study of carbon-based organic fertilizer,the application effect and its influence on human health and natural environment were evaluated.The results show that the overall fertility of organic fertilizer is better than that of traditional fertilizer,and it is better than the individual use of biochar and organic fertilizer,and the environmental impact is less than the single organic fertilizer,which is better than the traditional fertilizer,which can reduce the health risk of the human metal in the fruit of the tomato.It provides a reference for replacing traditional fertilizer with biochar based organic fertilizer,realizing the reduction application of traditional fertilizer and the soilization application of carbon based organic fertilizer. |
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