Effects Of Different Soil Amendments On Soil Nutrients And Fungal Communities At The Tillering Stage Of Sugarcane

Sugarcane is the most important sugar crop in China and even in the world.It is also often used as an important raw material for biomass energy,fiber material and feed production.The soil fertility of sugarcane area in China is poor,and the content of organic matter is generally low.In addition,long-term continuous cropping and large-scale application of chemical fertilizer lead to further decline of soil fertility.In recent years,straw returning and organic fertilizer input have become important measures to improve soil fertility and soil properties,but the related research is not comprehensive and systematic,the research results are quite different,and there is no conclusion of regularity and mechanism.Therefore,in this study,we studied the differences of soil nutrient index,soil enzyme activity and fungal community structure in different locations(rhizosphere and bulk soil)of newly planted sugarcane at tillering stage under four kinds of soil improvement treatments(CK:blank control;OM: organic fertilizer(peat soil);OS: organic fertilizer(peat soil)+ sugarcane leaves returning to the field;SS: sugarcane leaves returning to the field),and analyzed the effects of each treatment on the sugarcane agronomic characteristics and yield components at harvest time.It is proposed to provide scientific basis for technical measures and evaluation methods of soil improvement by using organic materialsreasonably.Research shows:1)Compared with the control,soil improvement significantly improved AK,TN,TC,C/N,SOM,DOC,DON and other soil nutrient indexes in the short term,of which OM treatment had a superior effect;during the short term(tillering period)after treatment in this study.Soil p H decreased significantly,especially in the rhizosphere soil of SS treatment.The treatment effect of all the tested indexes showed significant difference between rhizosphere and bulk,among which the TC,C / N,SOM of rhizosphere soil were significantly higher than that of bulk soil,and the effect of treatment with organic fertilizer(OM,OS)was more obvious;Each treatment,soil p H,AK,DOC and DON of rhizosphere soil were significantly lower than those of bulk soil.The AP,TN and TC of rhizosphere soil of sugarcane leaf returning treatment(SS)were significantly higher than that of the bulk soil,which reflected the main factors related to root metabolism demand and the biological feedback effect of root system on soil improvement.The above results provide an important reference for the construction of scientific soil improvement evaluation index system and sampling analysis technology.2)The main enzyme activity studies showed that the difference effect of soil enzyme activity in different sampling locations was greater than that in different soil improvement treatments,and soil enzyme activity in rhizosphere location was significantly higher than that in bulklocation.3)The diversity analysis of soil fungal community showed that the difference effect of different sampling locations were greater than that of different soil improvement treatments,indicating that the soil sampling location at the tillering stage of sugarcane was an important factor to evaluate the structural characteristics of the fungal community;the study also showed that the root growth and metabolism in the early stage of sugarcane might have regulatory effect of crop adaptability and stability on the fungal community in the rhizosphere soil.4)The results showed that Ascomycota and Mortierellomycota were significant interaction effect by different soil improvement treatments and different sampling locations.In addition,the soil fungi Basidiomycota,Mortierellomycota,unclassified＿k＿＿fungi and rozellomycota were more affected by different soil sampling locations compared with different soil improvement treatments,and the soil fungi Ascomycota was more affected by different soil improvement treatments compared with different soil sampling locations;The relative abundance of Mortierellomycota in bulk soil under OM treatment was significantly higher than that in other treatments,and the relative abundance of Ascomycota in rhizosphere soil under OM treatment was significantly higher than CK;the relative abundance of rozelomycota in SS treatment was significantly lower than CK and OM treatments.RDA analysisshowed that soil p H,EC,WC,AP,AK,TC,TN,C/N,DOC and DON could explain 72.38% of the influencing factors of fungal community structure,among which p H,TC,C/N,AP,SOM,AK,DOC and DON were the main influencing factors,The effects of p H,AK,DON and DOC on the main fungal groups were similar,while the effects of AP and SOM on the main fungal groups were similar.5)OM and OS treatments showed significant promoting effect on sugarcane growth(plant height,dry weight of aboveground biomass)at tillering stage,but had no significant promoting effect on root dry weight,tillering rate and NBI.At the harvest stage,the treatment with improved materials,especially the treatments with organic fertilizer(OM,OS)showed a comprehensive and significant promoting effect on sugarcane individual growth traits(plant height,stem diameter),population traits(effective stem number,sugarcane yield)and quality traits(sugar content).The stem diameter,sugar content and sugarcane yield of SS treatment were also significantly improved compared with the control.