| The eight-year continuous fertilization experiment farmland in Wangtuan Town of Tongxin County was used as the research object to reveal the evolution laws of different fertilization measures on the soil quality of cultivated land in Ningxia dryland.It will explore the the evolution law among the soil microbial community,soil physical and chemical properties of different fertilization measures as well as their relationship,which will also provide a scientific basis for promoting regional soil productivity and sustainable agricultural development.The main findings are as follows:(1)In terms of soil physical properties,the agglomerates in the dry sieve method are mainly in the range of>5mm and 5-2mm size fractions,accounting for 41%-54%of the total aggregates,which is the advantage of soil aggregates.In the>5mm and 5-2mm size fractions,the content of aggregates between chemical fertilizer and cow dung(T2)as well as sheep manure(T3)were the lowest,which were respectively 25.30%and 24.66%.Compared with the control(TO),it respectively decreased by 41.38%and 45.05%.Among the 5-2mm,2-lmm,and 1-0.5mm size fractions in the wet sieve method,the content of aggregates between chemical fertilizer and cow manure(T2)treatment were the highest,which were respectively 3.35%,2.64%,and 3.95%.Compared with the treatment without fertilizer(TO),it respectively increased by 87.15%,118.18%,and 113.51%.The single application of chemical fertilizer reached the highest level in the 0.5-0.25mm fraction,reaching 6.75%,which was 1.35 times of the no-fertilization(TO)treatment,and the difference reached a significant level(p<0.05).The organic carbon in the treated aggregates were mainly in the 2-lmm-scale aggregates.The total nitrogen content in the soil aggregates and the organic carbon content in the soil aggregates showed similar trends and all fertilization treatments could reduce the soil carbon-nitrogen ratio.(2)In terms of soil chemical properties,compared with no fertilization treatment,continuous fertilization for 8 consecutive years significantly increased soil total nitrogen,alkali nitrogen,available phosphorus,available potassium,and organic carbon.After the rise,the total phosphorus showed the downward trend.The soil pH has been reduced,from strong alkaline to alkaline.From 2011 to 2018,the pH of each treatment decreased by 7.08%,8.87%,9.65%,9.15%,6.71%and 5.07%.meanwhile,the soil pH decreased most in fertilizer with cow dung and sheep manure.(3)In terms of crop yield in 2017,single application of chemical fertilizer apparently increased the crop yield,which with chemical fertilizer combined with cow dung and sheep manure treatment reached the highest;in 2018,compared with the treatment without fertilization,single application of chemical fertilizer and chemical fertilizer combined with potassium fulvic acid respectively increased by 15.11%and 14.74%and there was no significant difference between treatments.The combination of chemical fertilizer with cow dung,sheep manure and bio-organic fertilizer significantly increased corn yield,respectively by 88.47%,118.90%and 38.42%.(4)In terms of soil microbial quantity and structure,organic combined with inorganic fertilizers is beneficial to increasing the biomass of bacteria,fungus and actinomycetes in soil;fertilizer combined with cow manure and sheep manure are reduced the ratio of Gram-positive bacteria to Gram-negative bacteria.Proteobacteria are the dominant bacteria in the soil in five different fertilization treatments.The analysis of the diversity of a showed that fertilization had no significant effect on the richness and diversity of soil bacteria. |
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