Recycling Potential Of Litter Of Common Greening Trees In Northern Cities

In order to explore the potential of recycling and reuse of the fallen leaves of common greening trees in northern cities,this study used Prunus cerasifera、Firmiana simplex、Ginkgo biloba、Koelreteria paniculata、Cerasus serrulata、Rhus typhina、Malus spectabilis、Broussonetia papyrifera、Aesculus chinensis and Liriodendron chinense etc.waiting for 10kinds of trees with fallen leaves as objects.Two experimental studies were carried out:（1）Using nylon mesh bag buried soil decomposition method,the decomposition law and nutrient release characteristics of 10 species of tree litter were studied.The purpose is to use tree litter as a fertilizing material for farmland（directly fertilize after crushing or as a biomass organic fertilizer additive material）Provide scientific basis;（2）Using the Petri dish filter paper method,the effects of 10 tree litter extracts on the seed germination and seedling growth of 4 crops including Cucumis sativus,Sorghum vulgare,Triticum aestivum and Brassica campestris were studied.The allelopathy effect is to provide a scientific basis for effectively avoiding the allelopathy inhibition on crops when the fallen leaves of trees are used as farmland fertilization.The main results are as follows:（1）The N content of Broussonetia papyrifera litter is higher(40.37 mg?g^-1),and the litter of Malus spectabilis,Cerasus serrulata,Rhus typhina,Prunus cerasifera,and Koelreteria paniculata are the next(21.25～27.50 mg?g^-1).The content of P is higher in Aesculus chinensis,Broussonetia papyrifera,Cerasus serrulata and Liriodendron chinense litter(12.92～23.03mg?g^-1).The K content is higher in the litter of Cerasus serrulata,Malus spectabilis,Broussonetia papyrifera and Prunus cerasifera(3.52～6.38 mg?g^-1)（2）Among the 10 types of trees,the litter of Broussonetia papyrifera,Rhus typhina and Prunus cerasifera decomposes quickly（T is 1.02～1.08 a）,Koelreteria paniculata,Liriodendron chinense,Cerasus serrulata,Malus spectabilis,Aesculus chinensis and Firmiana simplex followed（T is 1.12～1.18 a）,and Ginkgo biloba litter decomposed slowly（T is 1.22 a）.The correlation test shows that,the higher content of N and P in litter is beneficial to the decomposition of litter,while the higher content of lignin and higher lignin/N value in litter is not conducive to the decomposition of litter.（3）Broussonetia papyrifera,Cerasus serrulata and Rhus typhina（T is 1.02～1.22 a）are the fastest release of N element during the decomposition of litter,and the slower release of Ginkgo biloba（T is 9.15 a）;the faster release of P element is Malus spectabilis,Rhus typhina,Liriodendron chinense,Broussonetia papyrifera and Cerasus serrulata leaves（T is 1.01～1.18a）,Ginkgo biloba and Prunus cerasifera release slowly（T is 2.62～2.63 a）;for K element,except Aesculus chinensis and Ginkgo biloba,The release of litter is slightly slower（T is1.26～1.43 a）,and the release of other litter is faster（T is 1.00～1.05 a）.（4）The litter extract has a comprehensive promotion effect on Cucumis sativus seed germination and seedling growth,including Prunus cerasifera,Cerasus serrulata,Broussonetia papyrifera,Malus spectabilis,Koelreteria paniculata,and Aesculus chinensis（comprehensive principal component value F respectively:1.5072,1.0892,1.0282,0.6877,0.6668,0.4840,the same below）,the inhibitory effects are Ginkgo biloba,Firmiana simplex,Rhus typhina,Liriodendron chinense（F:-0.3967,-0.7596,-1.8695,-2.4373.respectively）;Litter extracts promoted the germination of Sorghum vulgare seeds and the growth of seedlings,including Cerasus serrulata,Malus spectabilis,Koelreteria paniculata,Aesculus chinensis,Broussonetia papyrifera,and Ginkgo biloba（F:1.7435,1.0228,0.8654,0.6652,0.4063,0.3046.respectively）,The inhibitory effects are Prunus cerasifera,Firmiana simplex,Liriodendron chinense,and Rhus typhina（F:-1.1134,-1.1886,-1.3105,-1.3951.respectively）;The litter extract has a comprehensive promotion effect on Triticum aestivum seed germination and seedling growth,including Firmiana simplex,Aesculus chinensis,Prunus cerasifera,Cerasus serrulata,Koelreteria paniculata,and Malus spectabilis（F:1.4416,0.8410,0.8129,0.5584,0.4209,0.2930.respectively）,the inhibitory effects are Broussonetia papyrifera,Ginkgo biloba,Liriodendron chinense,Rhus typhina（F:-0.2057,-1.0905,-1.1389,-1.9327.respectively）;The litter extract has a comprehensive promotion effect on Brassica campestris seed germination and seedling growth,including Cerasus serrulata,Malus spectabilis,Prunus cerasifera,Aesculus chinensis,and Broussonetia papyrifera（F:2.037,1.6368,0.9058,0.7645,0.3359.respectively）.the inhibitory effects are Koelreteria paniculate,Firmiana simplex,Ginkgo biloba,Rhus typhina,Liriodendron chinense（F:-0.4059,-0.6642,-0.8000,-1.7002,-2.0763.respectively）.（5）Combining the above results:1)According to the nutrient content and decomposition and release characteristics of different litters,it can be selectively and pertinently applied to farmland fertilization or preparation of biomass organic fertilizer.Among them,Broussonetia papyrifera,Koelreteria paniculata,and Prunus cerasifera are suitable as nitrogen fertilizers,Liriodendron chinense,Cerasus serrulata,Broussonetia papyrifera and Aesculus chinensis are suitable as phosphate fertilizers,and Prunus cerasifera,Broussonetia papyrifera,Malus spectabilis and Cerasus serrulata are suitable as potassium fertilizers;2)At least 3 types of litter such as Liriodendron chinense,Rhus typhina,Firmiana simplex and Ginkgo biloba have allelopathic inhibitory effects,so avoid the above 4 types of litter when fertilizing crops;3)The extracts of Cerasus serrulata,Malus spectabilis,Aesculus chinensis,Prunus cerasifera,Broussonetia papyrifera and Koelreteria paniculata litter have obvious comprehensive promotion effects on at least 3 kinds of crops.Therefore,it is recommended to fertilize directly as substrate fertilizer or develop potential tree species of bioorganic fertilizer.The litter extracts of Liriodendron chinense,Rhus typhina,Firmiana simplex and Ginkgo biloba have obvious comprehensive inhibitory effects on at least 3 kinds of crops.Therefore,they should not be used as base fertilizer and seedling fertilization when used as farmland fertilization,but they can be used as the potential for the development of biological herbicides species.