Along with the city to speed up the process of city development caused by the area of soil erosion, pollution or resource degradation, leading to the city soil quality and city ecological capacity challenges [1]. soil is purifier garden plant growth medium and environmental pollutants, is the main carrier of green belt and part of its fertility quality is directly related to the growth and ecological the effect of landscape garden plants play, green city soil quality directly determines the quality level of city greening [2-3]. therefore, in the management of ecological health in the process of city, improve the city greenbelt soil fertility quality is to give full play to the ecological benefits of city green space is an important measure of [4]. due to the effects of automobile exhaust and highway microclimate, city greening science with the characteristics of the soil will be changed, the soil compaction, soil fertility decline, heavy metal exceed the standard, pH change Phenomenon and so on. To this end, Zhang Qi et al. (2007) investigated and evaluated the soil fertility quality of Pudong highway greenbelt in Shanghai city; Zhen Hua et al. (2005) studied the relationship between soil erosion and TSP pollution in urban road greening. Based on the investigation of main roads in Pudong New Area Shanghai city greenbelt soil fertility quality, soil improvement by applying fertilizer, and the detection of soil nutrient characteristics and variation of greenbelt after fertilization, understand the road greenbelt soil nutrient status, provide the basis for the construction of green renovation projects and daily maintenance management.
1 test materials and methods
1.1 survey sampling sites
According to the growth status of the Pudong highway greening plants, selection of green belt soil survey sampling sites (Table 1), survey sites are mainly S20 Road (east 5 Ring Road (standard) and Zhang Yang island sea - Zhaojiagou bridge) a total of 2 regions in 8 sampling sites, sampling points to the ground, planting vegetation camphor (Cinnamomumcamphora), poplar (Populuseuramevicanacv. '), Bermuda (Cynodondactylon), Rose (Rosachinensis) etc.. In February 10, 2010, soil samples were collected at five points in each region, and soil sampling was divided into two layers, 30-60cm and 0-30cm were sampled. In December 10, 2010, soil samples were collected at the same point in 10 months after fertilization.
1.2 determination of physical and chemical properties of soil
The soil sample is natural air dry, and the aluminum box is used to load and load, and then put in the oven to bake, bake until a constant weight, then weigh, calculate the soil moisture content. The value of pH 2.5:1 water leaching potential method; soil electrical conductivity (EC) with a 1:5 ratio of water determination; organic matter is oxidized by K2Cr2O7 -- external heating method; effective phosphorus extraction with sodium bicarbonate; potassium with ammonium acetate extraction - Flame photometric method; nitrogen diffusion method [7].
2 soil improvement effect analysis and evaluation
2.1 soil pH and EC values
From (Table 2) analysis showed that in 0-30cm soil, fertilizing soil before pH was 8.21-8.65, the average value is 8.50; after pH fertilizer is 8.23~8.73, the average value is 8.55; in the 30~60cm soil layer, soil pH before applying for 8.32~8.79, the average value is 8.50; pH after fertilization was 8.39~8.79, average is 8.59. therefore, after fertilization, the greenbelt soil pH high.
In 30-60cm soil layer, the soil EC value was 0.049~0.099mS/cm, the average value of 0.071mS/cm was 0.1~0.3mS/cm, the EC value was 0.047~0.127mS/cm, the mean value was 0.108mS/cm, and the mean value was 34.25%, but the effect of applying fertilizer on EC was normal. The change of EC in 30~60cm soil layer was larger than that before fertilization, but the change of EC value of 0-30cm in the soil layer was smaller than that before fertilization.
2.2 soil nutrient content
Soil organic matter and nitrogen, phosphorus and potassium content of soil organic matter content of soil organic matter content was 17.27g/kg, mean 14.04g/kg, mean 12.03~16.24g/kg, mean 19.88g/kg, mean 11.86~18.24g/kg, 13.38~20.86g/kg, 0-30cm, and 30~60cm in soil. This showed that the soil organic matter content was 14.16g/kg, the mean value was 15.71~28.11g/kg, and the organic matter was not increased or slightly increased.
The effective phosphorus in soil was obviously improved, and the proportion of different soil layers was different (Table 3). The soil available phosphorus increased in some sampling points, and the soil available phosphorus was slightly decreased, which may be due to the uneven application of the process, but also with the garden plants to the effective phosphorus uptake rate.
Soil available potassium is an important indicator of soil potassium content. The content of soil total potassium is 1%~2%. The content of soil potassium is 101.8~287.7mg/kg. The content of 127.2~304.5mg/kg is 190.16mg/kg, the average is 216.55mg/kg, the content of soil available potassium is increased significantly, and the content of soil available potassium is increased by 30~60cm
From table 3, the total nitrogen content in soil was not significantly improved, but in 0~30cm soil layer, the soil nitrogen content was 0.99g/kg, the average content was 0.66g/kg., the soil nitrogen content was 0.32~0.98g/kg, the average content of soil sampling sites was 83.08%, which showed that the growth of garden plants was difficult to meet the requirements of soil nitrogen.
3 conclusions
For a long time, China's highway greening planning and landscape planting more attention but seldom pays attention to scientific maintenance, although many road green belt was weak, but few people to analyze the reasons, simply attributed to automobile exhaust and dust affects the growth of garden plants, take the death of plants and then replant the simple measures ground. The essence of soil quality is the main limiting factor to limit plant growth and ecological landscape effect, and how to improve and improve soil quality is one of the most important problems that need to be faced and solved in the construction of garden afforestation in Shanghai.
Because most of the roads are built, especially in the process of urban expansion in the process of building land are farmland or abandoned land, so the green belt is built on the barren land, garden plant growth lack of nutrition. According to the nutrient classification criteria of the second soil survey, the soil organic matter content of the highway greenbelt in Shanghai is of medium level. This study also shows that the average consumption of organic matter 1.55g/kg and the organic degradation rate of 9.5%. in the sampling period of 10 months.
PH, EC value and organic matter are the conventional projects in city. The quality of green land in Shanghai city. The results show that the pH value of the soil is not changed, and the effect of EC is still normal, but the effect of soil nutrient is obvious. N, P and K are essential nutrients for plant growth, and the application of modified soil directly affects the content of available phosphorus, available potassium and total nitrogen in soil.
Through data analysis, the effective phosphorus content in soil increased most, up to 2000 times; the content of available potassium, total nitrogen content increased by an average of 1/3; not only did not increase but decrease generally. This is mainly because the green belt soil is relatively poor, the use of fertilizer containing a large amount of nitrogen and phosphorus, garden plants to nitrogen and phosphorus potassium uptake is not balanced, it may be uneven, these factors lead to different sampling points of the sample, but overall, the amount of nitrogen absorbed by the garden plant, followed by phosphorus, potassium, at least.
In this study, the soil physical and chemical properties and soil nutrients from the point of view of the green belt landscape plant growth requires a large number of nutrients, poor soil often seriously affect the growth of plants. It is necessary to improve the soil by applying fertilizer, but it can not change the nature of the soil, and it can not meet the growth of garden plants. Therefore, it must be based on a large number of data acquisition and analysis, the use of adequate organic fertilizer, compound fertilizer, and even the use of fertilizer, to improve the soil physical and chemical properties and soil nutrients, and promote the growth of garden plants. In addition, if the soil improvement should be combined with the recycling of urban organic waste, and promote the recycling of waste recycling [3], this will be able to meet the development of the concept of circular economy, improve the ability of the entire urban ecosystem self good cycle, and create a good ecological environment of highway greening. (omitted)
Reference
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