Slow Released Fertilizer Preparation Process From Lignin Residue

China is a large agricultural production country,and agricultural production requires the application of large amounts of fertilizers.According to statistics,the annual fertilizer application in my country has exceeded 60 million tons,but the effective utilization rate of chemical fertilizers in my country is low,and the utilization rate of nitrogen,phosphorus and potassium has not exceeded 40%,which is lower than the international average.At the same time,excessive use of chemical fertilizers can easily cause problems such as accumulation of heavy metal pollution,reduction of microbial activity,difficulty in nutrient conversion and utilization,nutrient imbalance,salt accumulation,and acidbase balance imbalance.The relatively mild impact on the production and use of organic fertilizers is conducive to the sustainable development of agriculture.However,my country's organic fertilizer output cannot meet the application requirements,and fertilizer application is still dominated by chemical fertilizers.Lignin is one of the raw materials that can be used in organic fertilizers.Its output is second only to the renewable biomass resources of cellulose.The annual output of lignin in my country is more than 200 million tons,and its application potential is huge.At the same time,the current lignin is mainly derived from biomass refining industry wastes such as wood fiber ethanol and papermaking,which has a low utilization rate and easily causes environmental pollution.Therefore,the fertilization of lignin can not only fill the output gap of organic fertilizer,but also provide a channel for the utilization of high output value for lignin as biomass waste.Therefore,this study prepared lignin compound fertilizer,biochar base fertilizer and lignin slow-release fertilizer three kinds of fertilizers using lignin residue as raw materials,and studied the preparation process and fertilizer efficiency of the three fertilizers.The main research work and results are as follows:Using lignin residues as raw materials,fully mixed and ground with inorganic nutrients to prepare lignin compound fertilizer,leaching experiment was conducted under the same conditions as inorganic fertilizer,the soil leaching effect was compared,and the water absorption and water retention capacity of lignin compound fertilizer and its Slow release effect on N nutrients.The results showed that the lignin compound fertilizer increased water absorption and had a certain water retention effect,and its release rate in still water and soil slowed down.The adsorption effect of lignin compound fertilizer on aqueous solution to Pb(?) was determined.The result was that the lignin compound fertilizer adsorbed Pb(?) in aqueous solution was 8.93mg/g.The pot experiment was carried out,and the Chinese cabbage was planted for 18 days.The germination rate,leaf length,leaf width,dry weight and root length were tested.The results showed that lignin compound fertilizer can greatly increase the plant height of the Chinese cabbage(6.6 cm to 12.9 cm),And the combined application of lignin can make the root system of Chinese cabbage more developed(6.7 cm to 7.4 cm).The biochar material is prepared by hydrothermal method and high-temperature oxygen-limiting method using lignin residue,and then compounded with urea under high temperature and high pressure to prepare biochar base fertilizer.Soil leaching experiments were carried out to determine the water-absorbing and water-retaining capacity of the biochar-based fertilizer,the nitrogen element slow-release effect and the nitrogen element release rule.The results show that the water absorption capacity of the biochar-based fertilizer is enhanced but the water retention effect is not obvious.Carry out the adsorption experiment to determine the adsorption effect of biochar-based fertilizer on heavy metals in aqueous solution and soil.Considering the yield and adsorption capacity,FL500 has the strongest adsorption capacity of 46.3mg/g.In the experiment of lignin adsorption of heavy metals in soil,1:1 mixing of FL500 and lignin has the best adsorption effect on heavy metal Pb(?) in the soil.At this time,the heavy metal Pb(?) in the soil precipitation is already less than the content of heavy metal Pb(?) in the source water in the national standard Requirements(<0.01mg/l).A pot experiment was carried out,and the Chinese cabbage was planted for 18 days.The germination rate,leaf length,leaf width,dry weight and root length were tested.The result was that the biochar-based fertilizer could significantly increase the root length of the Chinese cabbage(2.1 cm to 7.4 cm)and Significantly increase the germination rate of Chinese cabbage(40% to 90%).The lignin residue is crosslinked with degradable polyvinyl alcohol(PVA)to prepare a nitrogen element slow-release film,and the slow-release film is used to prepare a ligninbased nitrogen element slow-release fertilizer.Control the film-forming conditions of nitrogen element slow-release film and select the best preparation conditions.Soil leaching experiment was carried out to determine the water absorption and water retention capacity of the lignin-based slow-release fertilizer,nitrogen element slow-release effect and nitrogen element release rule,and adsorption experiments were carried out to determine the heavy metal Pb(II)Adsorption effect.The results show that the ligninbased compound fertilizer has increased water absorption and has a strong water-retaining effect(the time when the water content is 10% is delayed by about 9 days).The ligninbased slow-release fertilizer has a strong slow-release effect in soil.Compared with inorganic fertilizer,it was slowed by 60%.A pot experiment was carried out.Eighteen days of Chinese cabbage were planted.The germination rate,leaf length,leaf width,dry weight and root length were tested.The results showed that lignin-based slow-release fertilizer can significantly increase plant roots.Long and fresh weight.