Combined Effects Of Tea Polyphenols And Low Molecular Weight Organic Acids On Theiron Species In Soil

During the planting process,tea trees produce plant polyphenols(PPs)and low molecular weight organic acids(LMWOAs),and enter the soil layer in a variety of ways to affect the chemical cycle of soil materials.A large amount of land in western Sichuan has been converted into tea planting.Studies have shown that tea polyphenols and low molecular weight organic acids produced by tea planting have certain effects on soil iron.In this study,macroscopically combined with microscopic methods,the first method was to change the rice field to the tea garden soil,and the combination of iron form continuous extraction and environmental magnetic technology was used to analyze the changes of soil iron form and iron oxide after tea planting.Lifting and culture experiments gradually analyze 2 plant polyphenols(ie epigallocatechin gallate(EGCG)and rutin)and 2 low molecular weight organic acids(ie citric acid and oxalic acid)for acidic,neutral,lime The distribution of iron form of purple soil.The results show:(1)Paddy fields and different tea planting years(3,6,and 10 years)The 110 cm soil in the tea garden soil is characterized by red iron(Red-Fe)> oxidizable iron(Oxi-Fe)> acid soluble iron(Acid-Fe);rice fields changed to tea gardens and as the tea planting period was extended,the soil Acid-Fe and Oxi-Fe in the surface layer(0-10cm)and sub-surface layer(10-20cm)increased significantly,while the whole soil Red-Fe decreased.After 3 years of rice field conversion to tea plantation,0~30cm soil showed mass magnetic susceptibility(MS),saturated isothermal remanence(SIRM),soft remanence(IRMs),and hard remanence(IRMh)decreased;With the extension of the tea age,the soil showed a trend of decreasing the magnetic parameters,and the ferrimagnetic minerals dominated the soil magnetic characteristics.After the paddy field was changed to tea garden,the soil gradually acidified and the organic matter accumulated,which made the ferrimagnetic mineral unstable,which further caused Red-Fe to dissolve and transform into Acid-Fe and OxiFe,and some iron oxide crystals with the extension of the tea planting period.Degree will increase.(2)Tea polyphenols(TPs)and low molecular weight organic acids(LMWOA)can increase the soluble purple iron(Fes)and the neutral purple soil Fes by the separate action of the acid polyphenols.For the calcareous purple soil,TPs will promote Its Fes increases,while LMWOA has the opposite effect.After the combination of EGCG and LMWOAs,both acidic and calcareous purple soils show that LMWOAs masks the dissolution of iron by EGCG by promoting the conversion of Fes into Fe(Fep);the combination of rutin and LMWOA is acidic.The dissolution of purple soil iron shows a synergistic effect,while the calcareous purple soil shows that LMWOA inhibits the dissolution of rutin on iron.For neutral purple soil,the combination of TPs and LMWOA can promote the conversion of free iron(Fed)to Fes.It weakens the inhibition of iron dissolution by PPs.(3)The results of indoor continuous culture experiments showed that both TPs and LMWOAs could activate residual iron in acid purple soil,but their effect was weakened with the extension of time,and their combined effect was enhanced,both of which could promote soil efficiency.The increase in iron,but as the culture time increases,its increase will be reduced,and the release of effective iron in the soil is inhibited.Under the action of phenolic acid,the soil magnetic minerals increased.Among them,rutin and EGCG will have fibrite in the early stage of culture,and the ferriite will increase.With the prolongation of culture time,hematite and goethite will be formed.In neutral purple soil,EGCG,rutin and citric acid can promote the conversion of Res-Fe to Red-Fe,while the interaction of oxalic acid and the combination of TPs and LMWOAs will transform Oxi-Fe and Red-Fe to Res-Fe,making more iron and layer.A combination of silicate minerals.EGCG and rutin can promote the increase of soil available iron in the early stage of culture.Under the combined action of oxalic acid,the effective iron content of soil can be increased,the magnetic minerals of soil increase,the ferrimagnetic minerals and incomplete antiferromagnetic minerals dissolve,and the culture is late.Magnetite and maghemite are formed;in calcareous purple soil,soil iron is converted from Red-Fe to Res-Fe to Res-Fe to Red-Fe with the prolongation of culture time.TPs and LMVOAs can increase the effective iron content of calcareous purple soil to a certain extent,and with the extension of culture time,the effect is enhanced,and soil magnetite and maghemite increase.