Effect Of Mulching With Smashed Stand Residue On Soil Fertility And Growth In Camellia Oleifera

In order to make full and efficient use of Camellia oleifera residue and reduce the use of chemical fertilizer,this experiment analyzed the effect of C.oleifera residue returning forest on soil fertility maintenance and fertilizer cultivation in C.oleifera forest,and provided a theoretical basis for the virtuous circle of C.oleifera forest ecosystem.Our study set up four different thickness of C oleifera residue cover treatments in 4-year-old C.oleifera forest.The cover thickness was 0 cm(control,H1),4 cm(H2),8 cm(H3),and 12 cm(H4).After covering,the sample sites were observed once every 3 months and continuously observed for one year.The growth status,soil physicochemical index and the changes of bacteria and fungi in rhizosphere soil were measured.The results are as follows:(1)Different cover thickness of C.oleifera residue can improve soil structure and increase soil fertility.The bulk density of different soil layer was decreased with different cover thickness,and the total porosity and soil moisture content were increased.With the increase of the covering thickness of C.oleifera residue,the bulk density of soil layer decreases first and then increases,while the change trend of total porosity of soil is opposite.The content of alkali-hydrolyzed nitrogen,available phosphorus,available potassium,organic matter,humic acid carbon,fulvic acid carbon and humic acid carbon was significantly increased by different mulching treatments compared with H1 treatment,but the effect on soil pH was not significant.And the longer the mulching time,the more significant the soil nutrient and humus content increased.In addition,the mulching treatment reduced soil polyphenol oxidase activity and increased soil cellulase,sucrase and urease activity.(2)Compared with H1 treatment,the reforestation of C.oleifera residues can significantly increase the gene copy number of bacteria and fungi in the rhizosphere soil of C.oleifera.Among them,the gene copy number of bacteria and fungi in the rhizosphere soil of H3 treatment is the highest.The gene copy number of bacterial and fungal in each treated soil was H3>H4>H2>H1、H3>H2>H4>H1,from high to low,respectively(3)The various mulching treatments promoted the growth and development of C.oleifera plants.Among them,the H3 treatment had the most obvious effect on the fresh weight,dry weight,tree height,ground diameter and crown growth of the C.oleifera plants.The H3 and H4 treatments slightly increased the fruit setting rate of the C.oleifera.Comparing with the H1 treatment,the total length,total root area,average root diameter and root tip number of C.oleifera treated with H3 and H4 increased significantly,but the total root volume of C.oleifera was not significantly affected by each mulching treatment.Covering C.oleifera residues can also effectively inhibit the growth of weeds.The thicker the mulching effect is,the H4 treatment of weeds coverage is only about 5%.(4)According to the comprehensive analysis of the principal component analysis method,one year after the oil-tea camellia residues were returned to the forest,the improvement effect of each treatment on the physical and chemical properties of the 0-15 cm soil layer of the oil-tea camellia forest was H4>H3>H2>H1 in order from high to low.The effect of improving the physical and chemical properties of 15-30 cm soil layer is H3>H4>H2>H1 from high to low,and the promoting effect on the growth and development of Camellia oleifera seedlings from high to low is H3>H4>H2>H1.In general,different coverage The effect of treatment to forest return was H3>H4>H2>H1.In conclusion,the residue mulching of C.oleifera can improve the soil permeability,increase the content of alkali hydrolyzable nitrogen,available phosphorus,available potassium,organic matter and humus,promote the growth and nutrient absorption of C.oleifera,increase the number of bacteria and fungi,and reduce the coverage rate of weeds.Comparing the effects of the above several treatments on the physical and chemical properties of soil,soil microorganisms,weed coverage and the growth and development of C.oleifera,it is more appropriate to cover the residues of C.oleifera with 8cm thickness.