One Thousand Questions in California Agriculture Answered

by Edward J. Wickson

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?

It is not unusual to find people who predict the rise of alkali almost anywhere except on their own premises. No one can exactly tell where alkali will go, because no one has complete knowledge of the water movement in underlying strata. Wherever the ground water rises on lower levels because of irrigation on higher levels there is danger of the rising of the alkali, for which the only cure is underdrainage with tile so that this rising water is carried to an outflow and not allowed to approach within three or four feet of the surface. If you have such an outflow and desire to undertake the expense of tiling, you can insure yourself against a serious rise of alkali indefinitely. We do not see, however, how alkali can rise to the higher lands of the valley. Its first effect would be to make lakes or ponds in the lowest parts of the valley, and even then the surrounding mesa lands would not be injured.

Plants Will Tell About Alkali.

Please give information as to the application of gypsum to my soil which is somewhat alkaline. I do not care to have an analysis made of my soil, and believe that you can advise me without it.

If your soil is too alkaline for the growth of plants you can demonstrate that fact by experiment, or if it is capable of being used by the application of gypsum, that also can be determined by experiment and noting the behavior of the same plants afterwards. It is rather a slow process but it is sure enough.

Litmus and Alkali.