Analysis and evaluation of soil fertility characteristics of Shanghai urban green area

The soil samples collected from both soil surface(0-30 cm)and soil profile(0-90 cm)in Shanghai urban green area were analyzed in terms of pH,electric conductivity(EC),and organic matter,N,P and K contents,and the soil fertility characteristics were comprehensively evaluated by the Nemoro index.The results indicated that the soil pH values were mostly 8.0-9.0,and 98.88%of the soils were over 7.5 in pH;The soil EC were mainly between 0.03-2.64 mS/cm and averagely0.17 mS/cm;The soils' organic matter contents were largely at a medium level;The soils' total N,total P and alkali-hydrolyzable N contents were basically at a medium to slightly low level;Most of the green area was lack of available P in soil,but the total K and readily available K were relatively rich.In terms of soil layers,the soil pH values varied less,while with the soil layer's depth increasing the soil EC increased but the organic matter,total N,alkali-hydrolyzable N,available P and readily available K contents decreased,and the contents in the surface soil were significantly higher than those in the subsurface and bottom soils;The total P and total K contents in the surface soil were higher than those in the bottom soil but there were not significant differences.The descending order of soil fertility was parks' green beltstreets' green beltroads' green belt.The comprehensive evaluation by the Nemoro index showed that the integrated soil fertility index in Shanghai urban green area was relatively low,being 0.9-1.8 in 63.94%of the soils and below 0.9 in 34.08%of the soils.The soil fertility was at a medium to infertile level,so soil improvement should be carried out appropriately.