| In order to evaluate the effect of walnut litter decomposition on the system evaluation,explore the potential allelopathy of walnut of litter and provide theoretical basis for the rational use of walnut litter,providing reference for scientific and reasonable choice of walnut forest crops,Juglans sigllata Dode was used as material to study the effect of walnut litter decomposition on physical and chemical properties of Juglans sigllata Dode and “Weiyu-3” rhizosphere soil,growth of Juglans sigllata Dode and potato “Weiyu-3” in pot culture experiments.Combined with natural grass test indoor and the wild ecological environmental survey of effect of walnut litter decomposition on plants and soil,ultimately analyzed the inf luence of walnut litter decomposition on receptor plant growth,soil environment and walnut site habitat.The following results were obtained.1.Compared with the original soil,adding walnut leaf to soil could decrease soil p H value,increase EC value,nutrient contents,microbial quantity and enzyme activities.Total nitrogen,total organic carbon and organic matter increased with the increasing of decomposition duration,temperature and leaf-to-soil ratio.Enzyme activities changed various with the different decomposition conditions,but the highest activities of alkaline phosphatase and catalase were associated with lower temperature(15℃),highest concentration(10:100)and shortest duration(0 days).Walnut leaf decomposition for 20 or 30 days,at 15 ℃ and with 10:100 ratios significantly promoted bacteria,fungi and total microbial quantity.2.Walnut husk decomposition could enhance and improve soil fertility.Soil p H,EC value,total nitrogen,total organic carbon,organic matter,total potassium contents,urease and alkaline phosphatase activity and the quantity of soil bacteria,fungi,actinomyc etes and total microorganisms increased with increasing the ratio of walnut husk power,and the highest values were all observed at the ratio of 10:100.The maximum value of soil nutrition indicators(Total nitrogen,phosphorus,potassium and total organic carbon,organic matter)and fungi and actinomycetes quantity mostly appeared in 0 ~ 30 d treatments,particularly in 20 d.In addition to the total nitrogen,catalase,and actinomycetes,the peak value of other measurement index were found at decomposed w ith 25℃.3.Walnut litter decomposition could improve the chemical and biological properties of Juglans sigllata Dode rhizosphere soil,improved soil fertility.Walnut litter could significantly increase iron walnut rhizosphere soil p H and EC value,TOC,OM,available N,available P,available K contents and microorganism quantity and soil enzyme activity,but the TN,TP,TK,C/N effect is not obvious.4.Treatments of 1.5,2,2.5 times itter’s annual amount could promote the growth of Juglans sigllata Dode,effect of lower levels of walnut litter treatment on Juglans sigllata Dode growth was not obvious.Middle and high concentration of walnut litter treatment could promote Juglans sigllata Dode root activity,promote absorption of mineral nutrition,then stimulated root growth.Walnut litter application promoted Juglans sigllata Dode photosynthetic pigment content,leaf POD and CAT activity and Pro content,but inhibited SOD activity and MDA content,and then walnut litter decomposition promoted the growth of Juglans sigllata Dode height and base diameter(except A1),blade and biomass accumulation.For promoting the growth of Juglans sigllata Dode,the optimal amount of returning litter was 1.5 times annual litter fall.5.Plant species of compositae and gramineae were not sensitive to walnut litter.Walnut litter decay could promote the growth of Poa annua L.and Bromus japonicus Thunb.ex Murr.and inhibit the growth of Galium aparine L..Both in artificial habitat(natural grass)and natural habitats,compositae and gramineae plant species within the canopy is significantly more than any other plant.Combined with field survey,compositae and gramineae were relatively not sensitive to walnut litter allelopathy compared with other plants,could achieve symbiosis with trees.6.Walnut litter had certain improvement effect on “Weiyu-3” rhizosphere soil chemical and biological properties.Walnut litter could improve “Weiyu-3” rhizosphere soil pH,EC value,available potassium content,fungi,actinomycetes quantity,invertase,alkaline phosphatase activity,but had no obvious effect on the urease activity,and inhibitied the quantity of bacteria and total microbial.The walnut litter improved “Weiyu-3” rhizosphere soil TOC,OM,TN,TP,TK,C/N,available N,available P ontents,but the rest treatments not reach significant difference levels compared with CK in addition to 10:100 treatment of.available N and available P.7.Walnut litter decomposition had a concentration effect on “Weiyu-3” growth and production.Treatments of 1.5,2,2.5 times itter’s annual amount restranted root activity,affected the absorption of N,P,K,Zn,B,significantly reduced “Weiyu-3” chlorophyll a and chlorophyll b,chlorophyll content of a+b,inhibited leaf photosynthesis,then inhibited “Weiyu-3” plant height,base diameter,branch number and stolon and root length,finally inhibited the potato tuber number and weight of per plant,inhibited of the accumulation of dry matter and plant biomass and the inhibition effect enhanced with the increasing of litter content.8.Walnut litter had different effect on soil chemical and biological properties in different habitats.Compared with the soil of canopy without walnut litter,walnut litter could improve the canopy soil microbial populations of every habitat,improved soil nutrient content,microbial number soil urease,alkaline phosphatase,and cellulose enzyme activity of canopy soil of artificial intercropping(intercropping with corn)and natural habitat.Artif icial habitat natural grass canopy soil microbial quantity was significantly more than in the soil outside the walnut tree. |
