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More work of this kind was done and other interesting results obtained, but the work so far has only been preliminary, and further details are postponed.
When theory only is considered, our soil would seem to need drains to carry off the rain-fall, and one would expect to see the water stand and stagnate on the surface with such an impenetrable clay subsoil as our experiments seem to show it to be, but observation and experience show otherwise. It took two days for an inch of water to pass through seven inches of the packed saturated clay subsoil in the cylinder. The soil of the Experiment Farm very quickly dries, however, even after a heavy rain, and is called a "thirsty soil.” Probably one reason for this is to be found in the fact that veins of quartz-rock traverse the clay in all directions. These can be seen in many places in this section, where cuts have been made for carriage or railroads. The soil seems to be naturally and thoroughly drained. In the process of root-washing, the writer has frequently come across quite large conduits of this kind of small broken rock in which apparently an unlimited amount of water can be poured and carried off. As a consequence of this good natural drainage, the crops were but slightly injured by the unusually wet spring. It remains to be seen what the effect will be of a long continued drought.
ON THE MOISTU'RE IN THE SOIL.
It is very important in this study of the soil and soil temperature and of the development of the cotton-plant, to determine what amount of water is present at certain frequent intervals of time and at certain depths of soil. A five-inch wrought-iron pipe just six inches long was used to take a succession of samples to any required depth. A sample of soil so taken, after being weigheid, was spread out on heavy wrapping-paper, and dried at the ordinary temperature of the air. When the samples were air-dry, they were again weighed and the loss in weight was counted as moisture. When this loss was figured into per cents of the original material, the results were found to vary so much as to be perfectly useless for the purpose of comparison. The stones and small rocks in each sample were then separated and weighed. It was intended that a sieve of ten meshes to the inch be used in this separation, but by mistake one of five meshes to the inch was used, and the mistake was not discovered until nearly one-half of the samples had been worked over, after which its use was continued. The material passing through this sieve was called “fine earth,” and it was assumed that all the water would be held in this and practically none in the stones and rocks. The per cent. of water figured on the original “fine earth" gave results which were much more intelligible, although, as will be seen, the per cents do not appear perfectly uniform, doubtless owing, in large measure, to the varying amounts of small stones still present. Practically, however, we have a very good idea presented of the amount of water held by the soil at the different depths, at the disposal of the crop. Owing to the irregular character of the soil, the results are not as exact as an ordinary chemical analysis performed in the laboratory is expected to be, but as preliminary work on the subject of soil temperature and plant development, and as a record the results are undoubtedly valuable.
As results expressed in per cent. are apt to convey but little meaning to the farmer, the amount of water is also calculated into pounds per acre. For this the capacity of the cylinder was found. It held 1980 c. c. of distilled water at 25.5°C. Without making an allowance for the temperature, it was found that the capacity of the sampler must be multiplied by 311374.15 for an acre, six inches deep, and this factor was used. The average weight of the fresh and air-dry soil and subsoil, and of the rocks contained in the sampler, and of the average amount of moisture contained in the air-dry soil and subsoil, is given, for a limited number of samples, the number of samples from which the average is taken being voted in the following table:
The amount of moisture remaining in the air-dry material was very constant for the different depths, the extremes varying but 0.4 per cent. for the first six inches, 0.7 per cent. for the second, 0.9 per cent. for the third, and 1.8 per cent. for the fourth. Part of this loss at 110°C. may have been due to oxidation, and as the amount of moisture so found was practically constant, its presence was disregarded. These results of themselves are of interest.
The following table gives the principal data obtained on this subject of soil moisture :
12 inches. 18 inches. 24 inches. 6 inches. 12 inches. 18 inches. 24 inches.
CONDITION OF SURFACE SOIL.
Cotton not all up.
Long, severe drought ended after this.
The record of the weights of stones in samples xix to XXXII was lost or mislaid in moving into our new buildings, per cent. of moisture in the “fine earth” is not given, and, for reasons above stated, the per cent, calculated on the original substance conveys so little meaning, that the pounds per acre only are given. It is to be remembered that determinations of this kind, however carefully performed, can never be as exact as could be wished. For instance, take an extreme case: the lowest weight of stones in the 24-inch sample was one 1} ounces, and the greatest 20 ounces, nearly four times greater thau the average weight of stones found at this depth. These stones would evidently not hold up so much water as the same weight of “fine earth,” but it would seem impossible to determine what the error would be. It is hoped that the relatively large amount of soil lised in these determinations and their number will help to make the results at least of comparative value.
Another thing that should be borne in mind is the distribution of the rain-fall, it having rained several times just before the sample was taken. The samples were taken, when possible, on Friday morning. The distribution of the rain-fall can be seen in the table of the sunshine record. This was mostly supplied by Mr. T. C. Harris, of the Department of Agriculture, from his gauge in Raleigh, as our large signal-service gauge was not in place at the time. An inch of water per acre weighs 225,960 pounds. In the last column the general condition of the soil of the Experiment Farm is given, as noted at the time, and may aid in recalling to mind the general character of the past growing season. Through all of June and to the middle of July the farmers were complaining of the unusually wet season. Cotton hardly commenced to grow until the 16th of July, when it took a start and for two weeks or more grew rapidly. By the 30th the farmers were complaining of the warm, dry weather. The following was entered in our note-book on this date:
“The ground contains just about moisture enough now for cotton and tobacco, if it had been about like this all along, but this hot, dry spell following the unusually wet season has occasioned much injury to the tobacco. Corn