Effects Of Organic Fertilizer On Microbial Diversity And Phosphorus Availability In Reclaimed Soil In Mining Area

In the process of coal mining and land consolidation,due to soil disturbance and large-scale equipment operation,the structure of newly reclaimed soil was destroyed,its quality was reduced,and its nutrients were poor,especially the content of available phosphorus in the soil was very low.Applying organic fertilizers could increase soil phosphorus content.However,were the effects of different organic fertilizers on soil available phosphorus and its effects on different profiles the same? In the process of reclamation,what was the response relationship of available P in calcareous soil with reclamation years? At what level of P application different organic fertilizers could achieve the maximum production efficiency of crops and how the microbial mechanism of P adsorption and desorption by organic fertilizers in soil with different P levels was still unknown.To this end,the paper depended on the positioning base fertilizer test（Shanxi Province Xiaoyi city Pian Cheng village in coal mining subsidence）,studied different organic fertilizers（chicken manure,pig,cow dung）in four phosphorus levels(0,25,50 and 100 kg·hm^-2)on the number of year of the reclamation,bacterial community structure and function of soil microbial diversity in the influence of carbon and phosphorus cycle related enzyme activity,and the characteristics of different organic fertilizers on corn for phosphorus,Olsen-P content in soil and soil phosphorus adsorption desorption of different organic fertilizers were investigated,which provided a scientific theoretical basis for the rational fertilization of reclaimed soil and the improvement of reclaimed soil micro-ecological environment in mining areas.The main findings were as follows:（1）The microbial diversity and the activities of carbon and phosphorus cycling-related enzymes all showed an increasing trend with the increase of reclamation years（except the number of soil fungi and the activities of dehydrogenase）.Compared with no fertilization treatment（CK）,all fertilization treatments significantly increased soil microbial biomass carbon（46.67%-131.57%）,microbial biomass phosphorus（246.57%-502.28%）,dehydrogenase activity(22.66%^-257.51%),phytase activity(36.61%^-206.39%),alkaline phosphatase activity（27.61%-105.21%）,invertase activity（88.36%-130.27%）,and microbial fungi numbers(90.78%^-233.76%).There was no significant difference between fertilization treatment and CK treatment in soil catalase activity at 3 years of reclamation.Fertilizer treatment had no significant effect on soil catalase activity at 4 years of reclamation,while organic fertilizer treatments significantly increased the activity of soil catalase.Compared with chemical fertilizer treatment,three years of organic fertilizer treatments significantly increased the number of soil bacteria,but did not significantly increase the number of microbial fungi and actinomycetes,catalase,alkaline phosphatase,dehydrogenase,phytase and invertase activities.After four years of reclamation,compared with chemical fertilizer,the activities of catalase（55.88%-123.53%）,alkaline phosphatase（19.04%-60.80%）and phytase（35.82-75.44%）were significantly increased by the three organic fertilizers.Compared with chemical fertilizer treatment,pig manure treatment significantly increased soil microbial biomass carbon（64.07%）,while cow manure treatment significantly increased soil microbial biomass phosphorus（73.78%）and soil fungus（69.42%）after four years of reclamation.In conclusion,the three kinds of organic manure increased soil microbial biomass carbon and catalase in the largest range.Among the three organic fertilizers,chicken manure increased the number of soil microbial bacteria,microbial biomass phosphorus,phosphatase,dehydrogenase and phytase.Cow dung treatment increased the number of fungi the most.（2）Bio Log-ECO technology was used to analyze the effects of different organic fertilizers(50kg·hm^-2 P level)on soil microbial carbon source utilization and microbial diversity index in three and four years of reclamation.The results showed that the AWCD value of each fertilization treatment increased with the increase of reclamation years.Among them,in the three years of reclamation,the order of the variation of soil AWCD value under different fertilization treatments with culture time was chicken manure ≥ cow manure ≥ pig manure ≥ chemical fertilizer.The four years of reclamation showed that pig manure ≥ cow manure ≥ chicken manure ≥ chemical fertilizer.In the third year of reclamation,compared with CK treatment,chicken manure treatment significantly increased the utilization degree of esters and acids carbon sources（766.67% and 462.50%）,while in the fourth year of reclamation,it significantly increased the utilization capacity of sugars and alcohols carbon sources（61.29% and 170.69%）.Compared with CK treatment,pig manure treatment significantly increased the utilization degree of carboxylic acid carbon sources（65.53% and 78.95%,respectively）,and cow manure treatment significantly increased the utilization degree of ester carbon sources（466.67% and 84.75%,respectively）compared with CK treatment.Principal component analysis showed that there was a significant difference between organic fertilizers and chemical fertilizer in the utilization of soil carbon sources,and the utilization of soil carbon sources was also different in different fertilization years.（3）Illumina Miseq high-throughput sequencing technology was used to analyze the effect of organic fertilizer treatment(50kg·hm^-2 phosphorus level)on bacterial community structure（three years of reclamation）.The results showed that the Chao1 index of Alpha diversity index of different treatments was pig manure ≥ chicken manure ≥ cow manure > fertilizer > CK,while the incense index and Simpson index were: Chicken manure ≥ chemical fertilizer ≥ pig manure ≥ cow manure ≥CK.The results showed that different organic fertilizers had different effects on soil microbial community structure.Compared with no fertilization（CK）,fertilization significantly increased the relative abundance of Proteobacteria and Acidobacteria.Compared with CK,the relative abundance of Firmicutes increased by 114.73% and144.74% in chicken manure and pig manure treatment,respectively.The relative abundance of Gemmatimonadetes in cow manure treatment was significantly higher than that in chemical fertilizer,chicken manure and pig manure treatment.The principal component analysis showed that fertilization changed the bacterial community structure,and the effects of organic fertilizer and chemical fertilizer on the bacterial community structure were different.RDA analysis showed that the activities of Olsen-P,phytase,alkaline phosphatase and catalase had a great influence on the diversity of soil bacterial community.Soil Olsen-P content was positively correlated with phytase,dehydrogenase,phosphatase and invertase,and negatively correlated with catalase.（4）In the process of mining reclamation,fertilization significantly affected maize grain yield,soil Olsen-P content and phosphorus adsorption and desorption characteristics.With the increase of reclamation years,soil Olsen-P content and desorption rate of all fertilization treatments showed an increasing trend,while soil phosphorus absorption showed a decreasing trend.Different fertilization treatments on corn grain yield,phosphorus uptake,phosphorus utilization,Olsen-P content and desorption rate were in the order of chicken manure ≥ pig manure ≥ chemical fertilizer ≥ cow manure.With the increase of P application level,the grain yield and P uptake of maize increased firstly and then remained unchanged,while the recovery rate of P fertilizer in season showed a downward trend.The content of Olsen-P increased with the increase of phosphorus application level.By constructing the 4-year P effect equation,it was found that the average optimal P application rate of chemical fertilizer,chicken manure,pig manure and cow manure were 66.51kg·hm^-2,37.25 kg·hm^-2,38.23 kg·hm^-2 and 59.98kg·hm^-2,respectively,and the theoretical maximum yield could be obtained for maize.Therefore,the recommended P application rate of organic fertilizer was less than that of chemical fertilizer.