| The Melaleuca alternifolia is a kind of tree with high economic benefit.However,due to the short introduction time,the influence of the Melaleuca alternifolia on the soil is neglected in the process of expanding the planting scale,and the basis for rational fertilization is lacking.How to improve each other?The yield of leaf white layer and the improvement of soil fertility in forest land are important issues in the development of Melaleuca alternifolia.In this paper,we studied 15 groups of different ages,and analyzed seven physical indicators,fourteen chemical indexes and four soil enzyme activities.The indicators were analyzed by one-way ANOVA,correlation analysis,redundancy analysis,principal component analysis,factor analysis,grey correlation analysis,etc.,and the soil fertility quality of the F.chinensis plantations in the red soil region of southern Hunan was evaluated.A more reasonable and reliable soil fertility quality evaluation system for the Melaleuca alternifolia plantation was established,which provided a scientific basis for rational fertilization and improvement of the economic benefits of the Melaleuca alternifolia plantation.The main conclusions are as follows:(1)There are significant differences in soil physical properties and non-capillary porosity indexes of 20-40cm and 60-100cm soil layers(p<0.05),and other physical indicators are between different forest ages.There was no significant difference(p>0.05).The soil water holding capacity and porosity index of the Melaleuca alternifolia plantations were lower than that of the control unforested shrubs.Among the fourteen chemical indicators measured,except for pH and total potassium,organic matter,total nitrogen,total phosphorus,alkali nitrogen,available phosphorus,available potassium,available calcium,available magnesium,available iron,effective manganese,effective copper,effective Zinc has significant differences in different ages.The chemical index content of the uncultivated grassland shrubs was mostly higher than that of the cross-leaf clematis plantations.The contents of pH,total nitrogen,total phosphorus,available potassium,available magnesium,available iron,available manganese,available copper and available zinc decreased with the increase of the age of the leaves.The total potassium,alkali nitrogen and available calcium content were significantly higher than those of other forests in the three-year-old plantation,and showed a significant downward trend in five years and seven years.The organic matter content was the lowest in the three-year-old plantation forest,and showed a slow increase trend in five years and seven years.The five-year-old plantation has the lowest available phosphorus content and has a small increase in seven years.(2)The soil urease activity,phosphatase activity,invertase activity and catalase activity of the uncultivated sloping land in the control plot were higher than that of the Melaleuca alternifolia.The invertase and the seven-year urease content were different in different soils.There was a significant difference between the layers,and the surface catalase activity was significantly different between different forest ages.The activities of urease,sucrase and phosphatase decreased firstly with the increase of forest age,and the activity of catalase decreased with the increase of forest age.Urease has the strongest correlation with phosphatase with a correlation coefficient of 0.61.Sucrase is most strongly associated with urease with a correlation coefficient of 0.432.Catalase is most strongly associated with urease with a correlation coefficient of 0.355.(3)Correlation analysis shows that except for the weak correlation between pH and chemical and physical indicators,there is a significant positive correlation between other chemical indicators and most physical indicators except bulk density.The bulk density has only a significant negative correlation with organic matter and a significant positive correlation with total potassium.There was also a strong correlation between soil urease,sucrase and catalase activity and chemical indicators.Phosphatase was only significantly correlated with organic matter,total phosphorus and total potassium.The results of redundancy analysis showed that the chemical indicators with strong correlation with soil enzyme activity were:organic matter,total phosphorus,total potassium,available potassium,available calcium,available manganese,available copper,and effective magnesium.Among a large number of elements,organic matter has the greatest influence on it,and effective calcium in medium and trace elements has the greatest influence on it.The most relevant enzyme with chemical indicators is catalase.(4)Based on the principal component analysis and the calculation of Norm value,the five data of effective magnesium,available potassium,total phosphorus,organic matter and catalase were determined as the minimum data for soil fertility quality evaluation of Melaleuca alternifolia.set.(5)The comprehensive scores obtained by factor analysis based on the full indicator showed that the soil fertility order of the different forest ages of the Melaleuca alternifolia was>control>three years>five years>seven years.The average composite score for the control was 0.701,with an annual average of 0.12,a three-year birth of-0.065,a five-year birth of-0.274,and a seven-year birth of-0.469.It is indicated that the results obtained by the factor analysis based on the full indicator are in line with the actual situation,which can explain the soil fertility of the different forest ages.(6)The results obtained by the soil quality index method and the grey correlation method based on the minimum data set MDS are significantly correlated with the comprehensive scores calculated by the full index factor analysis.The results can reflect the soils of different forest ages.The actual situation of fertility.The soil quality of the three results is all as follows:control>one year>three years>five years>seven years,of which the difference between five years and seven years is extremely small.The average SQI value of the group was 0.7712,the annual average was 0.546,the three-year life was 0.37,the five-year life was 0.2624,and the seven-year birth was 0.2615.The comprehensive scores calculated by factor analysis were normalized and correlated with SQI-MDS.The results showed that the overall trend was consistent,R2=0.9398.The average gray correlation coefficient of the control group was 0.7185,which was 0.5144 per year,0.4254 for three years,0.3846 for five years,and 0.3829 for seven years.After the normalized scores of the factor analysis were normalized and correlated with the gray correlation degree-MDS,the overall trend of the two was consistent,and R2 = 0.863.The results showed that the soil fertility quality decreased after planting the leaves,and a certain degree of soil fertility declined.The organic matter and P element were important factors affecting the soil fertility quality of the Melaleuca chinensis plantation in the study area.Should pay attention to the supplement of organic fertilizer and P fertilizer.In the future,reasonable human management measures should be taken to improve soil quality and better promote the sustainable development of the Baiji layer plantation industry. |
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