THE EFFECTS OF IRON IN THE SEWAGE IRRIGATION WATER ON SOIL PROPERTIES AND RICE GROWTH

The effects of iron in the sewage irrigation water flowing into the field on rice growth have been scarcely reported. This pot culture experiment aims at the effects of the sewage water with different concentration of iron on the soil pH, the contents of soluble and exchangable ferrous iron, the iron contents of the plant,the rice growth and yield. During two crops,it was found that the yield was remarkably reduced when the iron content in the sewage water was more than 1000 ppm; there was a tendancy of yield reduction when the iron content was between 600 and 800 ppm; no remarkable effects were observed when the iron contene was less than 600ppm;when the rice suffered from ferrous iron torxcity, disease occured at the middle part of the older leaf sheath. The iron content in the brown rice in the second crop was 4 to 9 times as that in the first crop.