Abstract: Soil bulk density is one of the important soil physical properties. Different soil with different soil bulk?density and stability，at the same time，soil regulation ability of soil-water，soil-gas，soil-heat capacity changed with?unstability of soil bulk density. It can improve soil fertility degree and the continuing demand factors of plant growth?if the soil's automatically adaptational ability was enhanced，therefore，it is necessary to research how soil bulk density vary and how to regulate and control it. In order to study the mechanism of the impact of soil physical properties?on high and stable yield of maize，this paper，with cultivated brown soil and pot experiment，studied the effect of soil?bulk density on maize root growth parameters(root length，root area，root volume)，furthermore，it studied the result?of regulation by application of organic fertilizer and simulation of different tillage depth in shenyang agricultural university. The results showed that soil bulk density had distinct effect on maize root growth，maize root growth index?showed downward with increased soil bulk density at the designing range of bulk density. When soil bulk density?changed from 1. 2 g/cm³to 1. 3 g/cm3，the maize root growth parameters were distinct difference among all treatments(P ＜0. 01)，and it was not obvious influence on maize root growth when soil bulk density over 1. 3 g/cm³，?meanwhile，maize root activity were significant distinction when soil bulk density exceed 1. 3 g/cm³，it showed decrease with soil bulk density growing(P ＜0. 01). Organic fertilizer is more effective to high soil bulk density compared with low ones，treatment effect were not obvious when organic fertilizer level were 4% and 5%，while it was?consecutive obvious for low soil bulk density at the designing range of soil bulk density，the reason was organic fertilizer significantly reduced the soil bulk density，at the same time it efficiently increased the soil porosity，water capacity and air porosity. With the thickness of tillage increased，plant height，stem diameter，total root length，chlorophyll a and yields of maize were decrease，but effect was not significantly distinct. Index of maize growth was not?changed when the top layer thickness adjustment to 30 cm to 40 cm，adding thickness was no longer apparent effect.?In brief，You must use organic fertilizer for compact soil which was good structure，simultaneously，using turn-over?tillage.

Key words: Soil bulk density, Maize(Zea mays L. ), Growth of root, Regulation

CLC Number: 

• S513.01