Talks on Manures Part 23

"The upper six inches of soil, one foot square, contained all the main roots of 18 strong plants; the next six inches, only small root fibres, and in the third section, a six-inch slice cut down at a depth of 12 inches from the surface, no distinct fibres could be found. The soil was almost completely saturated with rain when it was dug up on the 13th of September, 1866: Lbs.

The upper six inches of soil, one foot square, weighed 60 The second " " " 61 The third " " " 63

"These three portions of one foot of soil, 18 inches deep, were dried nearly completely, and weighed again; when the first six inches weighed 51 lbs.; the second six inches, 51 lbs. 5 oz.; and the third section, 54 lbs. 2 oz.

"The first six inches contained 3 lbs. of silicious stones, (flints), which were rejected in preparing a sample for a.n.a.lysis; in the two remaining sections there were no large sized stones. The soils were pounded down, and pa.s.sed through a wire sieve.

"The three layers of soil, dried and reduced to powder, were mixed together, and a prepared average sample, when submitted to a.n.a.lysis, yielded the following results:

Composition of Clover-Soil, 18 Inches Deep, From Part of 11-Acre Field, Twice Mown for Hay.

{Organic matter 5.86 {Oxides of iron 6.83 {Alumina 7.12 {Carbonate of lime 2.13 Soluble in {Magnesia 2.01 hydrochloric acid. {Potash .67 {Soda .08 {Chloride of sodium .02 {Phosphoric acid .18 {Sulphuric acid .17

{Insoluble silicious matter, 74.61.

{ Consisting of: {Alumina 4.37 {Lime, (in a state of silicate) 4.07 Insoluble in acid {Magnesia .46 {Potash .19 {Soda .23 {Silica 65.29 ----- 99.68 =====

"This soil, it will be seen, contained, in appreciable quant.i.ties, not only potash and phosphoric acid, but all the elements of fertility which enter into the composition of good arable land. It may be briefly described as a stiff clay soil, containing a sufficiency of lime, potash, and phosphoric acid, to meet all the requirements of the clover-crop. Originally, rather unproductive, it has been much, improved by deep culture; by being smashed up into rough clods, early in autumn, and by being exposed in this state to the crumbling effects of the air, it now yields good corn and forage crops.

"In separate portions of the three layers of soil, the proportions of nitrogen and phosphoric acid contained in each layer of six inches, were determined and found to be as follows:

Soil dried at 212 deg. Fahr.

1st six 2d six 3d six inches. inches. inches.

Percentage of phosphoric acid .249 .134 .172 Nitrogen 1.62 .092 .064 Equal to ammonia .198 .112 .078

"In the upper six inches, as will be seen, the percentage of both phosphoric acid and nitrogen, was larger than in the two following layers, while the proportion of nitrogen in the six inches of surface soil, was much larger than in the next six inches; and in the third section, containing no visible particles of root-fibres, only very little nitrogen occurred.

"In their natural state, the three layers of soil contained:

1st six 2d six 3d six inches. inches. inches.

Moisture 17.16 18.24 16.62 Phosphoric acid .198 .109 .143 Nitrogen .134 .075 .053 Equal to ammonia .162 .091 .064 Lbs. Lbs. Lbs.

Weight of one foot square of soil 60 61 63

"Calculated per acre, the absolute weight of one acre of this land, six inches deep, weighs:

Lbs.

1st six inches 2,613,600 2d six inches 2,657,160 3d six inches 2,746,280 =========

"No great error, therefore, will be made, if we a.s.sume in the subsequent calculations, that six inches of this soil weighs two and one-half millions of pounds per acre.

"An acre of land, according to the preceding determinations, contains:

1st six 2d six 3d six inches, inches, inches, Lbs. Lbs. Lbs.

Phosphoric acid 4,950 2,725 3,575 Nitrogen 3,350 1,875 1,325 Equal to ammonia 4,050 2,275 1,600 ===== ===== =====

"The proportion of phosphoric acid in six inches of surface soil, it will be seen, amounted to about two-tenths per cent; a proportion of the whole soil, so small that it may appear insufficient for the production of a good corn-crop. However, when calculated to the acre, we find that six inches of surface soil in an acre of land, actually contain over two tons of phosphoric acid. An average crop of wheat, a.s.sumed to be 25 bushels of grain, at 60 lbs. per bushel, and 3,000 lbs. of straw, removes from the land on which it is grown, 20 lbs. of phosphoric acid.

The clover-soil a.n.a.lyzed by me, consequently contains an amount of phosphoric acid in a depth of only six inches, which is equal to that present in 247 average crops of wheat; or supposing that, by good cultivation and in favorable seasons, the average yield of wheat could be doubled, and 50 bushels of grain, at 60 lbs. a bushel, and 6,000 lbs.

of straw could be raised, 124 of such heavy wheat-crops would contain no more phosphoric acid than actually occurred in six inches of this clover-soil per acre.

"The mere presence of such an amount of phosphoric acid in a soil, however, by no means proves its sufficiency for the production of so many crops of wheat; for, in the first place, it can not be shown that the whole of the phosphoric acid found by a.n.a.lysis, occurs in the soil in a readily available combination; and, in the second place, it is quite certain that the root-fibres of the wheat-plant can not reach and pick up, so to speak, every particle of phosphoric acid, even supposing it to occur in the soil in a form most conducive to 'ready a.s.similation by the plant.'

"The calculation is not given in proof of a conclusion which would be manifestly absurd, but simply as an ill.u.s.tration of the enormous quant.i.ty in an acre of soil six inches deep, of a const.i.tuent forming the smaller proportions of the whole weight of an acre of soil of that limited depth. It shows the existence of a practically unlimited amount of the most important mineral const.i.tuents of plants, and clearly points out the propriety of rendering available to plants, the natural resources of the soil in plant-food; to draw, in fact, up the mineral wealth of the soil, by thoroughly working the land, and not leaving it unutilized as so much dead capital."

"Good," said the Deacon, "that is the right doctrine."

"The roots," continues Dr. Vlcker, "from one square foot of soil were cleaned as much as possible, dried completely at 212, and in that state weighed 240 grains. An acre consequently contained 1,493 lbs. of dried clover-roots.

"The clover-roots contained, dried at 212 Fahr.,

Organic matter* 81.33 Mineral matter, (ash) 18.67 ------ 100.00 ====== * Yielding nitrogen 1.635 Equal to ammonia 1.985 Including insoluble silicious matter, (clay and sand) 11.67

"Accordingly the clover-roots in an acre of land furnished 24 lbs. of nitrogen. We have thus:

Lbs. of nitrogen In the six inches of surface soil 3,350 In large clover-roots 24 In second six inches of soil 1,875 --------- Total amount of nitrogen in one acre of soil 12 inches deep 5,249 Equal to ammonia 6,374 =========

Or in round numbers, two tons six cwt. of nitrogen per acre; an enormous quant.i.ty, which must have a powerful influence in encouraging the luxuriant development of the succeeding wheat-crop, although only a fraction of the total amount of nitrogen in the clover remains may become sufficiently decomposed in time to be available to the young wheat-plants.

CLOVER-SOIL FROM PART OF 11-ACRE FIELD OF BURCOTT LODGE FARM, LEIGHTON BUZZARD, ONCE MOWN FOR HAY, AND LEFT AFTERWARDS FOR SEED.

"Produce 2 tons of clover-hay, and 3 cwt. of seed per acre.

"This soil was obtained within a distance of five yards from the part of the field where the soil was dug up after the two cuttings of hay. After the seed there was some difficulty in finding a square foot containing the same number of large clover-roots, as that on the field twice mown; however, at last, in the beginning of November, a square foot containing exactly 18 strong roots, was found and dug up to a depth of 18 inches.

The soil dug after the seed was much drier than that dug after the two cuttings of hay:

The upper six inches deep, one foot square, weighed 56 lbs.

The next " " " 58 "

The third " " " 60 "

"After drying by exposure to hot air, the three layers of soil weighed:

The upper six inches, one foot square 49 lbs.

The next " " 50 "

The third " " 51 "

"Equal portions of the dried soil from each six-inch section were mixed together and reduced to a fine powder. An average sample thus prepared, on a.n.a.lysis, was found to have the following composition:

Composition of Clover-Soil Once Mown for Hay, and Afterwards Left for Seed. Dried at 212 Fahr.

{ Organic matter 5.34 { Oxides of iron 6.07 { Alumina 4.51 { Carbonate of lime 7.51 Soluble in { Magnesia 1.27 hydrochloric Acid { Potash .52 { Soda .16 { Chloride of sodium .03 { Phosphoric acid .15 { Sulphuric acid .19

{ Insoluble silicious matter, { 73.84. Consisting of: { Alumina 4.14 { Lime (in a state of silicate) 2.69 Insoluble in acid { Magnesia .68 { Potash .24 { Soda .21 { Silica 65.88 ----- 99.59 =====

"The soil, it will be seen, in general character, resembles the preceding sample; it contains a good deal of potash and phosphoric acid, and may be presumed to be well suited to the growth of clover. It contains more carbonate of lime, and is somewhat lighter than the sample from the part of the field twice mown for hay, and may be termed heavy calcareous clay.

"An acre of this land, 18 inches deep, weighed, when very nearly dry:

Lbs.