Influence of Phragmites australis on physical and chemical improvement of hedoro ground: Lysimeter experiment

The physical (dry bulk density, pF, cone index etc,) and chemical (Cl(-), SO4(2-), Na, EC etc.) properties of soil in each soil profiles were investigated in a Phragmites australis plot and a bare soil plot of lysimeter, where pipes of soil sampling are opened for about three years from April25, 1985 continuously without closing at a depth of 70 cm, to elucidate the influence of P. australis on the physical and chemical improvement of Hedoro ground. After comparing the P. australis plot with bare soil plot, it became clear that the improvement of Hedoro ground by P. australis is very effective in the physical and chemical properties of soil. The results obtained are as follows. 1) In the layers between surface and 10 cm deep of bare soil plot, the dry bulk density increases, compared to that in the P. australis plot. In the layers 20 and 100 cm deep of P. australis plot, the dry bulk density increased remarkably, compared to that in the bare soil plot. 2) The water retentivity in the P. australis plot becomes remarkably lower in layers more than 10 cm below the ground surface, compared to that in the bare soil plot. 3) The depth of the invasion of gaseous in the P. australis plot is greater than that in the bare soil plot. 4) The cone penetration index in the P. australis plot is greater than that in the bare soil plot in the layers between surface and 100 cm deep. 5) Exchangeable Na and exchangeable Ca contents of soils in the P. australis plot become lower in layers more than 70 cm below the ground surface, compared to those in the bare soil plot. 6) Exchangeable K content of soil in the P. australis plot becomes lower in the layers 10 and 70 cm deep, compared to that in the bare soil plot. 7) Cl(-) concentration of the soil in the P. australis plot becomes remarkably lower in the layers 10 and 100 cm deep. compared to that in the bare soil plot