| Coal gangue is one of the largest industrial solid wastes accumulated in China.Coal gangue is rich in silicon and aluminum,and it can be used to prepare silicon fertilizers if this silicon can be activated.This present study proposes a new method for preparing soil improvers from wastes.Industrial waste coal gangue and plant ash were mixed and calcined,and vinegar residue was added to prepare soil improvers,and provides a new way of thinking and methods for the comprehensive utilization of solid waste and environmental restoration.The main research contents and conclusions are as follows:(1)Through hydroponic experiments,explore the effects of single or mixed application of Si/K on the growth,physiology,ion absorption characteristics and micro-area distribution in ryegrass.When the ratio of Si: K was 1:2,the germination and growth indicators of ryegrass were significantly higher than other treatments.When the salt-alkali concentration was 50 mmol·L-1,the application of Si: K = 1:2 The germination rate was significantly increased by 47.7% under the 1:2 Si/K ratio as compared to the control,and it was 17.6% higher than the K application alone.It showed that the application of Si/K can alleviate the saline-alkali stress of ryegrass plants,obvious advantages were observed as compared to the silicon and potassium alone treatments.After mixed application of Si and K,the Na+ content in the leaves was reduced,more Na+ was presented in the soluble components in the roots and the cell wall,and the K+/Na+ in the roots,stems,and leaves of ryegrass was increased,thereby effectively alleviating the inhibitory effect of saline-alkali stress on plant growth.The above studies provided a theoretical basis for the application of silicon and potassium fertilizers and accurate ratios.(2)Preparation of silicon-potassium(Si-K)fertilizer through calcination experiment and characterization by ICP showed that the best calcination conditions were: 700 °C,1h,and coal gangue and plant ash ratio of 1: 4.XRD analysis found that compared to coal gangue and Ca CO3,K2CO3 mixed calcination,the silicon-potassium fertilizer prepared by calcining with mixture of coal gangue and plant ash contains more soluble silicon components(potassinite,potashite,sodalite,ferrosilicon Potassium acid and calcium silicate),resulting in increased silicon dissolution rate under acidic conditions.FT-IR results showed that the Si-O-Si bond disappeared.SEM analysis found that when calcined mixture of coal gangue and plant ash,particles agglomerated and sintered,and were rich in Al,Si,Ca,K,Mg,Na and other elements,which confirmed the oxides in the plant ash.(K2O,Ca O)reacts with the Si-O bond in coal gangue to reduce the crystallinity of Si,promote the dissolution of silicon,and reduce the dissolution of potassium.The above studies provided theoretical guidance for the preparation of silicon and potassium fertilizers.(3)Based on the best Si/K ratio from(1)and the best calcination conditions obtained from(2),vinegar residue was added to prepare Silicon-potassium fertilizer-based improver.Through soil culture experiment,comparing the effects of five treatments,it was found that compared with Si fertilizer and K fertilizer,the application of Si-K fertilizer increased the growth and physiological indexes of corn,and the application of Silicon-potassium fertilizer-based improver was more effective than Si-K fertilizer.It is obvious and significantly improves soil physical and chemical properties.After applying Silicon-potassium fertilizer-based improver,the K+/Na+ was increased by 1.3 times as compared to the Si-K fertilizer.The soil p H was reduced by 2.6% as compared to the Si-K fertilizer.The above results show that Si-K fertilizers can enhance soil fertility,enhance K+ absorption and transport,and vinegar can improve soil physical and chemical properties and structure.Therefore,the growth of maize plants could be improved by the application of Silicon-potassium fertilizer-based improver.The above research provided a theoretical basis for the application of silicon-potassium fertilizer-based modifiers in saline-alkali soil. |
