A study on the impact of soil thickness and matrix matching of roof garden on plant growth

Through observation and comparison of roof environmental factors and ground environmental factors, it can be known that roof is 3300lux stronger, 5% lower, 6°C higher and 0.6m/s faster than ground in terms of illumination intensity, relative humidity, temperature and wind velocity respectively at sunny midday. Set seven different soil thicknesses (8cm, 16cm, 20cm, 25cm, 30cm, 40cm), observe the growth of Aralia continentalis Kitagawa and determine all growth indexes including growth height, leaf length, leaf width, root length, numbers of lateral roots, etc. The results of determination are: all growth indexes increase significantly with the increase of soil thickness which ranges between 8 to 30cm; differences of growth indexes are not marked when soil thickness reaches more than 30cm. By carring out experimental observations on seven matching schemes of roof garden soil matrix, the best matching scheme is that the proportion of turfy soil, leaf mold and garden soil is 1∶1∶1. And the second best scheme is that the proportion between leaf mold and garden soil is 3∶2 while the proportion between turfy soil and garden soil is 1∶1.