One Thousand Questions in California Agriculture Answered

by Edward J. Wickson

Is there any simple soil test for alkali that can be made without a chemical analysis?

You can ascertain the presence of alkali by using red litmus paper, which will be turned blue by the alkali in the soil, if the soil is moist enough. This does not determine the amount of alkali, but the quickness of the turning to the blue color and the depth of the color are both attained when the alkali is very strong. When there is less alkali, the reaction is slower and weaker. This test, however, gives you only a rough idea whether the soil is suitable for growing plants. You can tell that better by the appearance of the plants which you find. Any druggist can furnish the litmus paper, and give you a demonstration of how it acts on contact with alkali.

Using Gypsum for Alkali.

Is it better, to kill the black alkali in the soil with gypsum, just to scatter it over an alkalied spot or to plow the soil first and then use the gypsum? I am going to sow alfalfa.

Use the gypsum after plowing, for it will wet down more quickly, and the gypsum has to be dissolved to act freely. The best way to cure your spot is to run an underdrain into it, if possible, so the rain-water can run through the soil freely and take the alkali with it.

Blasting or Tiling.

In planting trees where hardpan is four feet from the surface is it necessary to blast the hardpan, or is there no benefit derived by the blasting?

If there should be a good available soil under a shallow layer of hardpan, which you say is four feet from the surface, it might be of considerable advantage to bore into the hardpan and explode a dynamite cartridge in it. But if your good soil is really only four feet deep and hardpan continuous below, the blast might cause fissures which would prevent standing water in the upper stratum. If you are sure of four feet of good soil above the hardpan you will have no difficulty in growing good trees, if you get the moisture just right and the hardpan slopes in such a way that surplus moisture will move away. If, however, you have hardpan at different depths on the tract, so that it may really make basins which will hold water, you are likely to have trouble from accumulations of water which will not only prevent the roots extending to the full depths of the soil, but will also cause some trees to die. Such a danger could be removed by draining the soil to a depth of three and a half or four feet with tile, in order to prevent accumulations at any point. This would be expensive perhaps, but you would be sure that you had rendered your four feet of soil safe and available. If you trust to blasting you will have to wait several years for the trees to tell you whether you helped them or not.

Effects of Blasting.

I have land which is underlaid with hardpan two or three feet deep and this in turn is underlaid with sand or sandpan. What I would like to know is whether blasting the holes before setting trees would allow more moisture coming from this sandpan, or, rather, what effect it would have as to moisture.