Gypsum is not a cure for alkali, but simply a means of transforming black alkali into white, which is less corrosive and therefore less destructive to plants, but there may be easily too much white alkali present - so much that the land would be made sterile by it. You cannot remove alkali by flooding unless two conditions can be assured: first, that the water itself is free from alkali before application to the land; second, that you underdrain the land at a depth of from three to four feet with tile, so that the fresh water on the surface can flow through the soil into the drains, carrying away from the land the alkali, which it dissolves in its course. To flood land even with fresh water without making arrangements for carrying off the alkali water below, is to increase the alkali on the surface as the water evaporates, and such treatment does land injury rather than benefit. We cannot give you any estimate as to the cost of washing out. It depends altogether upon local conditions: whether you use hand work or machinery for the ditching, and what your water will cost. Alkali, Gypsum and Shade Trees. Kindly advise how to apply gypsum, and how much, to heavy, sticky soil, the worst sort of adobe and heavily saturated with alkali. We want to plant shade trees. Eucalyptus and peppers succeed fairly well after once started. Gypsum seems to help, but I don't know how much to use. The amount of gypsum required to neutralize black alkali depends upon how much black alkali there is to be neutralized, and no definite amount, therefore, can be prescribed beforehand as sufficient without a determination of the amount of alkali. In some experiments gypsum to the amount of thirty tons to the acre or more has been used just for the purpose of seeing how much the land would take, and a fine growth of grain has been secured after using that much gypsum, but that, of course, would be out of the question because the outlay would be more than the land or the crop would be worth. In the planting of trees at some distance apart, the tree can be protected from destruction and enabled to make a stand in the soil by using gypsum on the spot rather than the treatment of the whole surface. In this way five or ten pounds of gypsum could be used by mixing with the soil to fill a good-sized hole. Distribution of Alkali. I am told by all the ranchers on the east and south sides of the valley that their wells are excellent. But they all say that on the west side - they are bringing up alkali. One also said that the water level was rising throughout all the valley. Is it safe to depend on this in part, or will the alkali spread over all the valley and the foothills?