Study On Organic-mineral Complex Characteristics In Mengshan Tea Plantation Soils

The combination of soil organic maters and mineral was an important mechanism to form a good soil structure.As the active part of soil,soil organic-mineral complex closely impact the changes of soil fertility characteristics.The various phenomena and processes which take place in soil have relationship with organic-mineral complex.By way of collection soil samples outdoor and analysis indoor and taking the Mengshan tea plantation soil as the research materials,the paper investigated status of organic-mineral complexion, the Fe and aluminum oxides,the combined forms of soil humus,the composition of particle diameter of soil organic-mineral complex and the status of soil fertility.The relationships among all of these indexes under different planting-year were discussed too. The main results were as followed:(1)The content of organic carbon in tea plantation soil was 13.6～20.3g/kg,and the content of heavy soil organic carbon was 11.22～14.59g/kg.Both of them were increasing obviously with planting-year increasing.(2)The amount of organic-mineral complex of surface tea plantation soil of Mengshan was 10.97～13.99g/kg,and increasing with the increase of planting years.The degree of organic-mineral complex in tea plantation soil was 68.13～80.66%and was decreased following the increment of tea planting-year.Correlation analysis showed that the content of organic carbon was positively related with quality of organic-mineral complex and was negatively related with degree of organic-mineral complex.(3)The light organic carbon in tea plantation soil increased significantly greater than the heavy organic carbon,with the result that the organic-mineral complex degree decreased.However,in considering the proportion of increment to the total organic carbon, the heavy organic carbon content has increased significantly lighter than the light organic carbon,which represented additional complex quality and complex degree,and increased the amount of organic carbon that combined with soil minerals.(4)The content of soil free iron oxide was 11.68～12.38g/kg,and there were no clear difference and rules between tea plantation soil and the control and different planting year. The content of tea plantation soil amorphous iron oxide was in the range of 2.67～4.18g/kg, and increasing with the year of planting tea increased.The content of soil complex state iron was in the range of 0.545～0.567g/kg,the content of complex state aluminum was 0.0191～0.0199g/kg.The activation degree of iron was 22.81～33.76%.The correlation analysis showed that there was positive correlation between the tea plantation soil organic matter and amorphous iron,complex state iron and aluminum.(5)The content of tightly combined humus accounted for the most of humus in tea plantation soil,followed by the loosely combined humus,the content of stable combined humus accounted the least.The nature of Mengshan tea plantation soil was high acidity and low calcium which was the important reasons cause the content of loosely combined humus far more than the content of stable combined humus.After planting tea in natural soil,the content of loosely combined humus,stable combined humus and tightly combined humus were increased obviously.(6)The content of loosely combined humus,stable combined humus and tightly combined humus accounted for 38.06～43.32%,9.71～10.84%,46.61～52.23%in the heavy organic carbon,and the component was tightly combined humus＞loosely combined humus＞stable combined humus.The loosely and tightly combined humus accounted for most of organic matter in complex.The ratio of loosely and tightly combined humus was 0.73～0.93,more than the control,and changed with the increasing of planting year.(7)The＞50μm organic-mineral complex content was the most in organic-mineral complex components of tea plantation soil,followed by the 10～50μm organic-mineral complex content,＜2μm organic-mineral complex content was the lowest.Years of tea cultivation,making the content of sand-class complex reduced,the content of clay-class complex increased,improved the sand-soil texture,but complex of the sand level was still the main complex.(8) Compared with the control,the organic carbon content in each particle diameter of organic-mineral complex was increased in different degree as the planting-year increased. The＜2μm organic-mineral complex hold most of the organic carbon.The trend of distribution of organic carbon content in each organic-mineral complex of unit weight of soil and its percentage ratio of total carbon shown in fine silt level(2～10μm)＞clay level (＜2μm)＞sand level(＞50μm)＞coarse silt level(10～50μm). (9) Nutrient indicators of Mengshan tea plantation soil were higher than those of control,and had varying degrees of growth with the extending of planting year.Correlation analysis showed that the heavy organic carbon,the quality of organic-mineral complex,the content of loosely combined humus,the stable combined humus,the tightly combined humus,the total nitrogen,the alkaline nitrogen,the available phosphorus,the available potassium had significant positive correlation.