Influence Of Sugarcane Straw And Goat Manure On Soil Nutrients Transformation And Bacterial Communities Composition

Over-use of synthetic fertilizers especially nitrogen in modern agriculture not only cause soil acidification and contamination but also reduce the soil fertility in China.However,in China,sugarcane is considered main field crop having large biomass and requires extensive inorganic fertilizer for a long time.On the contrary,raw cane stalks are harvested for sugar industries and remaining approximately 20%of sugarcane field biomass including shoots,leaves,and leaf sheaths are compressed and discarded from the fields.These straws hold extensive amounts of carbon,nitrogen,phosphorus,potassium and other trace elements,as well as huge cellulose,which can contribute to nutrients transformation.Unfortunately,farmers commonly burn the sugarcane straw which is recognized as a traditional practice which not only contaminates the environment but also damages the nutrients.But,only organic materials(straw and manure)amendment in the organic farming system is a very beneficial strategy,which reduces the extensive use of synthetic fertilizers,improves crop yield and soil fertility(SF)as well as ensures the ecosystem sustainability.The primary advantages of this practice are determined by the activities of soil microorganisms.However,goat manure(M),single straw(S)and goat manure plus straw(MS)amendment influence the soil bacteria,their activities,and SF in clay-loam soil remains un-definable.Therefore,this study distinguished the effect of M,MS and S amendment on multiple bacterial communities structure and their activities,and availability of nutrients including the transformation in a clay-loamy soil with respect to two different phases(50&100 days).For this purpose,high-throughput-sequencing(HTS)strategy and soil enzyme activity(SEA)analyses were performed to evaluate bacterial communities' compositions and their activities.Amendment of both M and MS significantly improved the soil pH and available nutrients,especially N,C,K,and P as well as SEA for C and N cycles in both phases.Additionally,the increase in nutrient availability was more in M and MS amended-soil in the second phase(100 days)compared to the M and S amended-soil in the first phase(50 days).Moreover,plant growth promoting and lignocellulose degrading bacterial genera were enhanced under M and MS amended-soil compared to CK and S amended-soil in both phases.M amended-soil was dominated by these genera(Simiduia,Luteimonas,Azoarcus,Opitutus,unidentified Xanthomonadales,Altererythrobacter)as compared to CK,MS and S amended-soil whereas MS amended soil was dominated by genera(Proteiniphilum,Petrimonas,Ruminofilibacter,Thermomonas,Pseudomonas,Hydrogenophaga,Arenimonas)as compared to CK,M and S in the first phase(after 50days).Whereas in the second phase,dominant genera(SM1A02,Chryseolinea,unidentified Xanthomonadales,Altererythrobacter)were found in the M amended-soil as compared to CK,MS and S amended-soil.Likewise,MS amended-soil was dominated by Paludibaculum,Candidatus jettenia,and Opitutus as compared to CK,M and S amended-soil in the second phase(100 days).Distance-based redundancy analysis(dbRDA)showed that soil pH,carbon-nitrogen ratio(C:N)and nitrates(NO3-)were inducing least changes,while total nitrogen(TN),total carbon(TC),available nitrogen(AN),total phosphorus(TP),available phosphorus(AP),available potassium(AK)and ammonium(NH4+)were main the operators of variation in bacterial populations.Overall,this study increased our current knowledge that M and MS amendment is better than S amendment to improve the SF in the clay-loamy soil in both phases,but more fertility was exhibited in the second phase.Additionally,straw amendment with manure or only manure is satisfactory to improve SF as compared to the single straw amendment.This study also highlighted the role of time in nutrients transformation under different organic amendment types,which will be supportiv? to explain the mechanism of nutrients cycling.Moreover,in organic farming,these results can also provide the proper awareness for the organic amendment to increase nutrients for crop productivity.