The Story of the Soil Part 18

asked Percy.

"No, we have not done that," answered the Chief. "Those are old methods of investigation which have been tried for many years and yet no chemist can tell in advance what will be the effect of a given fertilizer upon a given crop on a given soil."

"That is true," said Percy, "but neither can any merchant tell in advance just what effect will be produced on the next day's business by the addition of a given number of a given kind of shoes to a given stock on his shelves. There are many factors involved in both cases."

"Yes, you are right in that," said the Chief, "we are just beginning to understand the chemistry of the soil, and we hope soon to have very complete proof of the advanced ideas we already have concerning the causes of the fertility and infertility of soils."

"Referring to the specific case of the Leonardtown loam of Maryland," said Percy, "I find the following statement on page 33 of the Report of the Field Operations of the Bureau of Soils for 1900.

After describing the Norfolk loam of St. Mary County, the writer says:

"'The Leonardtown loam is a very much heavier type of soil. It covers about forty-one per cent. of St. Mary County. The soil is a yellow silty soil, resembling loess in texture, underlaid by a clay subsoil with layers or pockets of sand. This soil has been cultivated for upward of two hundred years, but it is now little valued and is covered with oak and pine over much of its area. It is worth from $1 to $3 per acre. The cultivated areas produce small crops of corn, wheat, and an inferior grade of tobacco.'"

"The generally low estimation in which this land is held is probably wholly unjustified," replied the Chief. "There are two or three farms in the area which, under a high state of cultivation with intelligent methods, will produce from twenty to thirty bushels of wheat per acre and corresponding crops of corn. Those farmers are a credit to the country. They furnish the towns with good milk and b.u.t.ter and vegetables, and they also help to keep the towns clean and sanitary by hauling out the animal excrements, and other waste and garbage that tend to pollute the air and water of the village."

"I can see how that might maintain the fertility of those farms,"

said Percy. "It seems that the general condition of this kind of land is about the same in Prince George County. On page 45 of the 1901 Report of the Field Operations of the Bureau of Soils, I have noted the following statement:

"'The Leonardtown loam, covering 45,770 acres of the area, is the nearest approach among the Maryland Coastal Plain Soils to the heavy clays of the limestone regions of Western Maryland and Pennsylvania.

The surface is generally level and the drainage fair. The soil is not adapted to tobacco, and has consequently been allowed to grow up to scrub forest, so that large portions of it are at present uncleared. Such unimproved lands can be bought for $1.50 to $5.00 an acre, even within a few miles of the District line. The soil has been badly neglected, and when cultivated the methods have not been such as to promote fertility. When properly handled, as it is in a few places, good yields of wheat, corn and gra.s.s are obtained.'"

"That's right," said the Chief, "exactly right. Upon the whole it is one of the most promising soils of the locality, although it is not considered so by the resident farmers."

"You mean that it should be handled the same as is done by the successful farmers of St. Mary County?" inquired Percy.

"Yes, it needs thorough cultivation and the rotation of crops; and the physical condition of the soil needs to be improved by the addition of lime and manure, or green crops turned under."

"I have been looking over some of the other Reports of Field Operations," said Percy." I became interested in the description of a Virginia soil called Porters black loam. I find the following statements on page 210 of the Report for 1902:

"'The Porters black loam occurs in all the soil survey sheets, extending along the top of the main portion of the Blue Ridge Mountains in one continuous area. This type consists of the broad rolling tops and the upper slopes of the main range of the Blue Ridge Mountains. Locally the Porters black loam is called "black land" and "pippin" land, the latter term being applied because, of all the soils of the area, it is pre-eminently adapted to the Newtown and Albermarle Pippin. This black land has long been recognized as the most fertile of the mountain soils. It can be worked year after year without apparent impairment of its fertility.

Wheat winter kills, the loose soils heaving badly under influence of frost. The areas lie at too high elevations for corn. Oats do well, making large yields. Irish potatoes, even under ordinary culture, will yield from two hundred to three hundred bushels per acre. It seeds in blue gra.s.s naturally, which affords excellent pasturage.

Clover and other gra.s.ses will also grow luxuriantly upon it. The areas occupied by this soil are mostly cleared.'"

"Yes, Sir," said the Chief, "the Potters black loam is a fine soil--loose and porous as stated in the Report. You see it has a good physical condition."

"There is one other description in this Report for 1903 that is of special interest to me," said Percy. "This relates to a type of soil which the surveyors found in the low level areas of prairie land in McLean County, Illinois, and which they have called Miami black clay loam. I think we have several acres of the same kind of soil on our own little farm. I found the following statements on page 787:

"'When the first settlers came to McLean County they found the areas occupied by the Miami black clay loam wet and swampy, and before these areas could be brought under cultivation it was necessary to remove the excess of moisture. With the exception of a few large ditches for outlets, tile drains have taken the place of open ditches. Drainage systems in some instances have cost as much as $25 an acre, but the very productive character of the soil, and the increase in the yields fully justify the expense. There are few soils more productive than the Miami black clay loam. Some areas have been cropped almost continuously in corn for nearly fifty years without much diminution in the yields.'"

"Now there you are again," said the Chief. "Drainage, that's all it needed. You see it's a simple matter; and that's what the Leonardtown loam needs in places. Give it good drainage and good cultivation with a rotation of crops, and you'll get results all right."

"Has the Bureau of Soils tried these methods on any of this soil near Washington?" asked Percy.

"No use," replied the Chief. "We've got the scientific facts and besides, as I told you, some few farms are kept up in both Prince George and St. Mary counties and they are as good demonstrations as anyone could want. Now I suggest that you meet some of our scientists."

CHAPTER XXII

THE CHEMIST'S LABORATORY

THE Chief showed Percy into the laboratories of the Bureau and introduced him to the soil physicist and the soil chemist. Percy was greatly interested in the various lines of work in progress and gladly accepted an invitation to return after lunch and become better acquainted with the methods of investigation used.

In the afternoon the physicist showed him how the soil water could be removed from an ordinary moist soil by centrifugal force, and the chemist was growing wheat seedlings in small quant.i.ties of this water and in water extracts contained in bottles. The seedlings were allowed to grow for twenty days and then other seedlings were started in the same solution and also in fresh solution, and it was very apparent that in some cases the wheat grew better in the fresh solutions.

The chemist explained that he also a.n.a.lyzed the soil solutions and water extracts from different soils and that there was no relation between the crop yields and the chemical composition of the soils.

"But it seems to me," said Percy, "that your a.n.a.lysis refers to the plant food dissolved in the soil water only at the time when you extract it. How long a time does it require to make the extraction?"

"As a rule we shake the soil with water for three minutes and then it takes twenty minutes to separate the water from the soil. This gives us the plant food in solution and with the addition of more water the nitrates, phosphoric acid, and potash in the soil immediately dissolve sufficiently give us a nutrient solution of the same concentration as we had before. Thus there is always sufficient plant food in the soil so long as there is any of the original stock."

"That is surely quick work," said Percy, "but I wonder if the corn plant might not get somewhat different results from the soil a.n.a.lysis which it makes."

"How do you mean?"

"Did you ever plant a field of corn and then cultivate it and watch it grow with increasing rapidity, until along about the Fourth of July every leaf seemed to nod its appreciation and thanks as you stirred the soil; and to show its grat.i.tude, too, by growing about five inches every twenty-four hours when the nights were warm?"

"No," replied the Chemist, "I have never had any experience of that sort. I am devoting my life to the more scientific investigations relating to the fundamental laws which underlie these soil fertility problems."

"Well, I was only thinking," Percy continued, "that you a.n.a.lyze a fraction of a pound of soil in a few minutes, while the corn plant a.n.a.lyzes about a ton of soil by a sort of continuous process, which covers twenty-four hours every day for about one hundred and twenty days, and it takes into account every change in temperature and moisture, the aeration with any variation produced by cultivation, and also the changes brought about by the nitrifying bacteria and all other agencies that promote the decomposition of the soil and the liberation of plant food, including the action upon the insoluble phosphates and other minerals of the carbonic acid exhaled by the roots of the corn plants, the nitric acid produced by the process of nitrification, and the various acids resulting from the decay of organic matter contained in the soil."

"I am very familiar with the literature of the whole subject of soil fertility," replied the Chemist, "and our theories are being accepted everywhere. I have just returned from a lecture tour extending from Florida to Michigan, and our ideas and methods are being very generally adopted, not only in this country but also in Europe."

"The Chief of the Bureau very kindly permitted me to look over the maps and reports relating to the soils of Maryland and Virginia,"

said Percy, "but in this literature I found no data as to the amount of plant food contained in the various soil types that have been found in the surveys. May I ask if the Bureau has made any a.n.a.lyses to ascertain the total amounts of the different essential plant food elements contained in these different soils?"

"No," the Chemist replied, "a chemical a.n.a.lysis gives practically no information concerning the fertility of the soil. We have made no ultimate a.n.a.lyses of soils, although we have used the same methods of a.n.a.lysis in a study of the partial composition of the soil separates, or particles of different grades, such as the sand, the silt, and the clay."

"And have you also determined the percentages of sand, silt, and clay in the soils themselves?"

"Oh, yes, the physical composition of the soil is a matter of very great importance, and this is always determined and reported for every soil. Did you not see that in the Reports you examined this morning?"

"I think I did notice it," Percy replied, "but it is so easy for the farmer himself to tell a sandy soil from a clay soil that I did not appreciate the value of those physical a.n.a.lyses.

"In any case, I shall be very glad to know what results were obtained from the chemical a.n.a.lysis of the soil separates to which you referred."

"Those results are all reported in Bulletin No. 54 of the Bureau of Soils," said the Chemist, "and I have extra copies right here and will be glad to present you with one. And let me give you our Bulletin 22 also. This will enable you to get a clear idea of the principles we are developing which are solving the soil fertility problems that have completely baffled the scientists heretofore."