| North district of Yan'an new area is a typical city of cutting mountains to enlarge the area of the city.However,the urban soil conditions restrict the growth of urban landscape plants,especially the restricted soil conditions in the road greenbelt.It is difficult for cultivated plants to play its role in ecological protection function.In the present study,the field sampling and laboratory analysis were employed to determine the plant growth status of the road greenbelt in main road of north district of Yan'an new area,incuding Yangjialing,Yinjiagou,and Administration Committee of Yan'an New Area(AC),the soil physical and chemical indexes were measured,and the soil fertility was evaluated by referring to the classification standard of second National Soil Census and the Nemero index method.Based on that,the soil improvement plan was prepared,which provided a scientific basis for the improvement of the soil fertility of the road greenbelt in north district of Yan'an new area.The main results are as follows:1.The soil fertility of road greenbelt in north district of Yan'an new area is quite poor.According to the classification standard,the soil organic matter(mean 16.39 g kg-1)was classified into grade 4 and the content is low,the alkali-hydrolyzed nitrogen(mean 7.16 mg kg-1)was classified into grade 4 with low content,the available phosphorus(mean 5.57 mg kg-1)was classified into grade 4 and it is low in content,while the available potassium(mean 44.24 mg kg-1)was classified into grade 5 with very low content.The soil p H was range from 8.47 to 9.21,in overall the soil exhibited the alkaline-strong alkaline.The soil bulk density was 1.31 g cm-3-1.83 g cm-3,and the bulk density greater than 1.35 g cm-3 accounted for 88.88% of the total.The content of available nutrients and organic matter in soil in the soil layer of 20-40 cm is lower than that in the 0-20 cm.The analysis of the comprehensive fertility index of nemero indicated that the soil in the road greenbelt of Yan'an new district(north district)was classified into the level 4 and the fertility of soil was poor(< 0.9).2.There was a significant positive correlation between root activity and electrical conductivity.In addition,the leaf area was positively correlated with the content of available nitrogen,while it was negatively correlated with the content of available phosphorus.Similarily,the water content of leaf was positively correlated with its electrical conductivity.However,it was negatively correlated with the content of the available phosphorus.The content of plant chlorophyll was negatively correlated with soil bulk density.3.Soil minimally invasive transfixion combined with gen sheng products and bi long products can improve soil physical and chemical properties and soil fertility to a certain extent.The application effect of this technology is different in different areas.For the soil in the road green belt of the Guanweihui,the one-time additive application with minimally invasive perforation was the best.Compared with the control group,the p H and bulk density decreased by 8.29% and 20.16%,and the content of available P increased by 122.12%.For the soil of Yangjialing road green belt,the content of available K increased significantly by 31.33% with minimally invasive transplanting and one-time additive application compared with the control group.For the soil of Yinjiagou road green belt,the minimally invasive transplanting combined with two times of additive application has the best effect,the soil bulk density is reduced significantly by 15.38%,available N and available K are increased by 158.70% and 22.05%..4.Soil minimally invasive penetrating combined with additive has significant influence on plant physiological indexes.This technique can significantly improve leaf area,leaf water content,chlorophyll content and root activity.Due to the difference of plant physiological characteristics,investigation time and soil characteristics,the improvement effect of each section is different.All the three improved methods can promote the increase of leaf area and chlorophyll content to some extent.For Ginkgo biloba in green belt of Yangjialing Road,minimally invasive penetration combined with one time of additive has effect on plant leaf area,leaf water content,chlorophyll and root activity,among which root activity is increased by 17.09% compared with the control group.For Catalpa ovata from Yingjiagou Road,the minimally invasive penetrating combination with twice application of additives had the best effect on the improvement of leaf area and root activity,and the root activity increased by 76.38% compared with the control group.However,for chlorophyll content,the minimally invasive penetrating combination with once application of additives had the best effect.For Aesculus chinensis in the road green belt of the Guanweihui,minimally invasive threading combined with two times of additive application can effectively improve the leaf area,chlorophyll content and root activity of plants,among which the root activity was significantly increased by 64.95% compared with the control group. |
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