1. The regularities of the transformation of the ferrous sulphate in the soils and organic manure, and the mechanisms of the effect of ferrous sulphate on controlling chlorosis of apple tree were studied. 2. The chlorosis of apple tree was cured rapidly by the application of 2% ferrous sulphate solution to the roots in hole, at a rate of 60 liters per tree. The curative effect lasted a month.3. By application of a mixture of ferrous sulphate and organic manure in the ratio 1:20 (or 1:10;1:5) to the roots in hole, at the rate of 22.5 kilograms per tree, the chlorosis of large apple tree was cured after a month. The curative effect lasted about a year. Injuries occured by watering after the treatment with the mixture in the ratio 1:5. 4. Favorable effect was acquired in hole application of mixture of ferrous sulphate and organic manure in the ratio 1:20 (or 1:10) at the rate of 22.5 kilograms per tree after the application of 2% ferrous sulphate solution 60 liters per tree. The curative effect of this method lasted about a year. 5. The application of manure alone to the root zone was ineffective under our experimental conditions.