| Continuous cropping obstacles have become a common phenomenon in crop production,which directly leads to soil degradation,thereby reducing crop yield and quality.Unreasonable fertilization is one of the main reasons for this problem,and combined application of soil amendments and chemical fertilizers is one of the effective measures to improve soil environment and promote crop growth.Therefore,in this study,Chinese cabbage was used as the experiment material to compare the effects of chemical fertilizer reduction combined with biochar,microbial agents,organic fertilizers,silicon-calcium-magnesium-potassium fertilizers on the growth and development of Chinese cabbage and soil fertility.Biochar was then selected,setting different biochar application rates(12,24,48 t/hm~2)and combined with Bacillus subtilis XF-1,discuss effects of single application of different dosages of biochar and biochar/XF-1 combined application treatments on the growth and development,nutrient absorption,rhizosphere soil fertility and microbial diversity of Chinese cabbage.The main results and conclusions are as follows:1.Field experiment on reduced chemical fertilizers combined with biochar,microbial agents,organic fertilizers,and silicon-calcium-magnesium-potassium fertilizers was carried out.The results showed that compared with CK,the application of biochar and organic fertilizer increased the VC content,soil urease and invertase activities of Chinese cabbage,the increase was 25.34%-49.58%,3.75%-33.21%and 42.75%-109.74%,respectively.And the application of biochar and organic fertilizer significantly increased superoxide dismutase(SOD)activity,peroxidase(POD)activity and soluble sugar and soluble protein accumulation,the increases were 31.48%-65.66%,52.69%-114.25%,45.04%-62.38%and24.09%-33.19%,respectively.And the content of malondialdehyde(MDA)of Chinese cabbage was reduced by 50.63%-81.89%.Reduced chemical fertilizer combined with each amendment increased the yield of Chinese cabbage,but the difference was not significant compared with CK.The results of correlation analysis show that:the yield of Chinese cabbage was mainly affected by soil urease activity,superoxide dismutase(SOD)activity and MDA content.VC content was regulated by soil invertase activity and plant root morphology.Due to the original soil fertility difference of the two areas,the effect of the amendments in the two areas was not completely the consistent.Compared with CK,the addition of organic fertilizer significantly increased the content of available phosphorus and available nitrogen in soil of Beigou village.There were no significant differences in soil p H and nutrient content among treatments in Fangcaiguan village.2.The results of single application of biochar and biochar/XF-1 combined application experiment showed that,compared with the control,the single application of different dosages of biochar increased the plant height,plant width,head longitudinal diameter and chlorophyll content of Chinese cabbage in different degrees,and promoted the growth of roots,nutrient absorption,increased the activity of SOD,POD,CAT and reduced the content of MDA,and increased the content of soluble sugar,protein and vitamin C,the effect of T2 treatment(24 t/hm~2 biochar)was the best.Compared with the single application of biochar,biochar/XF-1 combined application had better effects on the growth and development,yield and quality of Chinese cabbage.However,the difference was not significant,and the effect of T6 treatment(24 t/hm~2 biochar+XF-1)was better.Both the single application of biochar and biochar/XF-1 combined application increased the yield of Chinese cabbage,but the difference was not significant.Compared with CK,the single application of different amounts of biochar increased the soil p H,organic matter,total nitrogen,total phosphorus,total potassium,available phosphorus,available potassium content,and urease and invertase activities,thus the soil fertility was enhanced.Compared with the single application of biochar,biochar/XF-1 combined application had better effects on the improvement of soil nutrient content,but the difference was not significant.T6treatments had the best effect on improving soil nutrient content.Under T6 treatment,the total nutrients(organic matter and total nitrogen)of the rhizosphere soil of Chinese cabbage in two areas increased by 92.66%-202.23%and 14.77%-35.04%,respectively;the available potassium content increased 215.90%-275.90%;the activities of invertase and urease were increased by 140.81%-195.27%and 33.75%-51.20%,respectively.The effect of T2treatment was secondly better.The correlation analysis results showed that the yield was significantly positively correlated with soil organic matter,total nitrogen,available potassium content,urease activity,total root length and root tip number.3.The bacterial diversity and richness of the rhizosphere soil of Chinese cabbage increased under the single application of biochar and biochar/XF-1 combined application.The soil bacteria diversity and richness were the highest under T6 treatment.Biochar application increased the relative abundance of Actinobacteriota,Chloroflexi and Firmicutes.Biochar/XF-1 combined application increased the relative abundance of Arthrobacter,Sphingomonas and Bacillus genera at the genus level.Among them,the relative abundance of Bacillus genera of the rhizosphere soil of the two varieties increased under the single application of biochar and biochar/XF-1 combined application treatments.And the relative abundance of Bacillus genera under each biochar/XF-1 combined treatment was higher.The correlation analysis results show that norank-f--JG30-KF-CM45 and norank-f--norank-o?Gaiellales were significantly positively and negatively correlated with soil invertase activity,p H,total phosphorus,available phosphorus,organic matter,available potassium,total nitrogen and total potassium content,respectively.In summary,single application of biochar and biochar/XF-1 combined application can promote the growth,nutrient absorption,stress resistance and quality of cabbage,and can improve the soil fertility and the richness and diversity of bacteria of cabbage rhizosphere soil,can increase the relative abundance of dominant bacteria in soil to improve the rhizosphere environment of cabbage plants and promote growth and development.T6(24t/hm~2 biochar combined with Bacillus subtilis XF-1)has the best effect,followed by T2(24t/hm~2 biochar). |
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