Effects Of The Essential Oil Extraction Residues Of Melaleuca Alternifolia On Soil And Stand Growth

With the continuous management of Melaleuca alternifolia plantation,the quality of forest soil continues to decrease,and some problems such as soil hardening,gradual weakening of microbial community,serious loss of water and fertilizer,and reduced management sustainability are highlighted.In addition,the residue of Melaleuca alternifolia essential oil after extraction has some problems,such as random dumping and difficult reuse.In view of the above reasons,the residue of Melaleuca alternifolia essential oil was tried to be returned to forest.In this study,three experimental groups(compound fertilizer group CF,residue group FR,residue+microbial agent group FR+EB)and one control group(CK)were set up,with a total of 12 standard experimental plots,to explore the decomposition law and nutrient release characteristics of residues in woodland environment,and their effects on the physical and chemical properties of plantation soil,the growth of Melaleuca young forest and the distribution characteristics of undergrowth vegetation.Make full use of Melaleuca alternifolia essential oil to extract residues,and at the same time,achieve the purpose of improving the soil quality of plantation and promoting the growth of stand,and explore a new way for the management of plantation.The research results are as follows:(1)The decomposition rate of essential oil extracted residues from Melaleuca alternifolia treated with microbial agents was significantly higher than that of untreated residues.At the end of the experiment,the mass residue rates of FR group and FR+EB group were 43.5%and 26.8%,respectively.Compared with the initial nutrient content,the contents of C,N,P and K elements in the residue were all reduced,and the decreasing ranges were 2.3%～8.3%,6.4%～8.8%and 8.7%～10.3%,respectively.The nutrient release amounts were 2.71～3.56 t hm-2,74.1～94.4 kg hm-2,1.122～1.391 kg·hm-2 and 13.2～16.4 kg·hm-2,respectively.The release amounts of four nutrient elements in FR+EB group were higher than those in FR group.In addition,Olson model predicted that the time required for complete decomposition(t95%)of FR group and FR+EB group was 3.83a and 2.25a(2)The application of Melaleuca alternifolia essential oil extraction residue has certain influence on the physical and chemical properties of the soil in the middle and upper layer(0-40cm)of the plantation,while the application of compound fertilizer has little influence on the physical properties of the soil in the plantation,but has certain influence on the chemical properties of the soil in the middle and upper layer.0-20cm soil layer,FR group or FR+EB group significantly reduced soil bulk density,increased soil capillary porosity,non-capillary porosity,total porosity,natural water content,alkalihydrolyzable nitrogen,available phosphorus,available potassium,organic carbon,humic acid and fulvic acid content;20-40cm soil layer,FR group or FR+EB group significantly increased the soil non-capillary porosity,available potassium,organic carbon,humic acid and fulvic acid content;In 40-60cm soil layer,the two residue application groups had no significant effect on soil physical and chemical properties.It can be seen that,with the increase of soil depth,the influence ability of residue on soil gradually decreases.(3)Applying the residue of Melaleuca alternifolia essential oil and compound fertilizer can promote the growth of plantation.Compared with the control group,the height of Melaleuca alternifolia in CF group,FR group and FR+EB group increased by 8.0%～14.5%,ground diameter increased by 3.9%～9.2%,crown width increased by 7.5%～36.4%,biomass increased by 18.7%～40.3%,and oil yield per plant increased by 33.3%～56.FR and FR+EB groups increased the root-shoot ratio of Melaleuca alternifolia by 45.6%and 79.4%,while CF group decreased the root-shoot ratio of Melaleuca alternifolia by 16.2%.Compared with compound fertilizer application,residue application has greater potential for promoting the growth of Melaleuca alternifolia.(4)The residue extracted from Melaleuca alternifolia essential oil can inhibit the undergrowth vegetation,but the difference between compound fertilizer and control group is not significant.Compared with the control group,the coverage of undergrowth in FR group and FR+EB group decreased by 57.1%and 51.6%respectively,the species number of undergrowth decreased by 51.1%and 49.6%respectively,and the biomass of undergrowth decreased by 48.2%and 20.7%respectively.The application of residues inhibited the growth of undergrowth vegetation,and made more space,light and soil nutrients available for the growth of Melaleuca alternifolia seedlings,thus promoting the growth of Melaleuca alternifolia seedlings.Conclusion:The decomposition rate of essential oil extracted residues from Melaleuca alternifolia treated with microbial agents was obviously accelerated,and at the end of the experiment,the nutrient release was significantly higher than that of untreated residues.The application of residues can effectively improve the physical properties of middle and upper soil,reduce soil bulk density,increase soil porosity and natural water content,increase the available N,P,K content,organic matter and humus content in different degrees,and improve soil fertility.It significantly promoted the growth of Melaleuca alternifolia young forest,and significantly increased the height,ground diameter,biomass,root-shoot ratio and oil yield per plant of artificial forest.But also inhibits the growth of weeds under the forest.On leftovers forests decomposition time+bacterium agent is 2.25 a,in line with Melaleuca alternifolia thousand layer recovery cycle,this pattern can be used in the practical application to improve oil extraction residue recycle and plantation of output,after drug treatment of Melaleuca alternifolia thousand layer oil extraction residue to forest can replace compound fertilizer application,in order to achieve the purpose of sustainable management.