Talks on Manures Part 25

"Proposition No. 5, will not be disputed; and I think we may accept No.

6, also, though we can not be sure that allowing clover to go to seed, had anything to do with the increased quant.i.ty of clover-roots.

"Proposition No. 7, may or may not be true. We have no proof, only a 'probability;' and the same may be said in regard to propositions Nos.

8, 9, and 10."

The Deacon seemed uneasy. He did not like these remarks. He had got the impression, while Charley was reading, that much more was proved than Dr. Vlcker claims in his Summary.

"I thought," said he, "that on the part of the field where the clover was allowed to go to seed, Dr. Vlcker found a great increase in the amount of nitrogen."

"That seems to be the general impression," said the Doctor, "but in point of fact, we have no proof that the growth of clover, either for hay or for seed, had anything to do with the quant.i.ty of nitrogen and phosphoric acid found in the soil. The _facts_ given by Dr. Vlcker, are exceedingly interesting. Let us look at them:

"A field of 11 acres was sown to winter-wheat, and seeded down in the spring, with 13 lbs. per acre of clover. The wheat yielded 40 bushels per acre. The next year, on the 25th of June, the clover was mown for hay. We are told that 'the _best part_ of the field yielded three tons (6,720 lbs.) of clover-hay per acre; the whole field averaging 2 tons (5,600 lbs.) per acre.'

"We are not informed how much land there was of the 'best part,' but a.s.suming that it was half the field, the poorer part must have yielded only 4,480 lbs. of hay per acre, or only two-thirds as much as the other. This shows that there was considerable difference in the quality or condition of the land.

"After the field was mown for hay, it was divided into two parts: one part was mown again for hay, August 21st, and yielded about 30 cwt.

(3,360 lbs.) of hay per acre; the other half was allowed to grow six or seven weeks longer, and was then (October 8th), cut for seed. The yield was a little over 5 bushels of seed per acre. Whether the clover allowed to grow for seed, was on the richer or poorer half of the field, we are not informed.

"Dr. Vlcker then a.n.a.lyzed the soil. That from the part of the field mown twice for hay, contained per acre:

First six Second six Third six Total, 18 inches. inches. inches. inches deep.

Phosphoric acid 4,950 2,725 3,575 11,250 Nitrogen 3,350 1,875 1,325 6,550

"The soil _from the part mown once for hay, and then for seed_, contained per acre:

First six Second six Third six Total, 18 inches. inches. inches. inches deep.

Phosphoric acid 3,975 4,150 3,500 11,625 Nitrogen 4,725 3,350 2,225 10,300

"Dr. Vlcker also ascertained the amount and composition of the clover-_roots_ growing in the soil on the two parts of the field. On the _part mown twice for hay_, the roots contained per acre 24 lbs. of nitrogen. On the _part mown once for hay, and then for seed_, the roots contained 51 lbs. of nitrogen per acre."

"Now," said the Doctor, "these facts are very interesting, _but there is no sort of evidence tending to show that the clover has anything to do with increasing or decreasing the quant.i.ty of nitrogen or phosphoric acid found in the soil_."

"There was more clover-roots per acre, where the clover was allowed to go to seed. But that may be because the soil happened to be richer on this part of the field. There was, in the first six inches of the soil, 3,350 lbs. of nitrogen per acre, on one-half of the field, and 4,725 lbs. on the other half; and it is not at all surprising that on the latter half there should be a greater growth of clover and clover-roots.

To suppose that during the six or seven weeks while the clover was maturing its seed, the clover-plants could acc.u.mulate 1,375 lbs. of nitrogen, is absurd."

"But Dr. Vlcker," said the Deacon, "states, and states truly, that 'more leaves fall on the ground when clover is grown for seed, than when it is mown for hay; and, consequently, more nitrogen is left after clover-seed than after hay, which accounts for wheat yielding a better crop after clover-seed than after hay.'"

"This is all true," said the Doctor, "but we can not accept Dr.

Vlcker's a.n.a.lyses as proving it. To account in this way for the 1,375 lbs. of nitrogen, we should have to suppose that the clover-plants, in going to seed, shed _one hundred tons_ of dry clover-leaves per acre!

The truth of the matter seems to be, that the part of the field on which the clover was allowed to go to seed, was naturally much richer than the other part, and consequently produced a greater growth of clover and clover-roots."

We can not find anything in these experiments tending to show that we can make land rich by growing clover and selling the crop. The a.n.a.lyses of the soil show that in the first eighteen inches of the surface-soil, there was 6,550 lbs. of nitrogen per acre, on one part of the field, and 10,300 lbs. on the other part. The clover did not create this nitrogen, or bring it from the atmosphere. The wheat with which the clover was seeded down, yielded 40 bushels per acre. If the field had been sown to wheat again, it probably would not have yielded over 25 bushels per acre--and that for want of available nitrogen. And yet the clover got nitrogen enough for over four tons of clover-hay; or as much nitrogen as a crop of wheat of 125 bushels per acre, and 7 tons of straw would remove from the land.

Now what does this prove? There was, in 18 inches of the soil on the poorest part of the field, 6,550 lbs. of nitrogen per acre. A crop of wheat of 50 bushels per acre, and twice that weight of straw, would require about 92 lbs. of nitrogen. But the wheat can not get this amount from the soil, while the clover can get _double the quant.i.ty_. And the only explanation I can give, is, that the clover-roots can take up nitrogen from a weaker solution in the soil than wheat-roots can.

"These experiments of Dr. Vlcker," said I, "give me great encouragement. Here is a soil, 'originally rather unproductive, but 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 produces 40 bushels of wheat per acre, and part of the field yielded three tons of clover-hay, per acre, the first cutting, and 5 bushels of clover-seed afterwards--and that in a very unfavorable season for clover-seed."

You will find that the farmers in England do not expect to make their land rich, by growing clover and selling the produce. After they have got their land rich, by good cultivation, and the liberal use of animal and artificial manures, they may expect a good crop of wheat from the roots of the clover. But they take good care to feed out the clover itself on the farm, in connection with turnips and oil-cake, and thus make rich manure.

And so it is in this country. Much as we hear about the value of clover for manure, even those who extol it the highest do not depend upon it alone for bringing up and maintaining the fertility of their farms. The men who raise the largest crops and make the most money by farming, do not sell clover-hay. They do not look to the roots of the clover for making a poor soil rich. They are, to a man, good cultivators. They work their land thoroughly and kill the weeds. They keep good stock, and feed liberally, and make good manure. They use lime, ashes, and plaster, and are glad to draw manure from the cities and villages, and muck from the swamps, and not a few of them buy artificial manures. In the hands of such farmers, clover is a grand renovating crop. It gathers up the fertility of the soil, and the roots alone of a large crop, often furnish food enough for a good crop of corn, potatoes, or wheat. But if your land was not in good heart to start with, you would not get the large crop of clover; and if you depend on the clover-roots alone, the time is not far distant when your large crops of clover will be things of the past.

AMOUNT OF ROOTS LEFT IN THE SOIL BY DIFFERENT CROPS.

"We have seen that Dr. Vlcker made four separate determinations of the amount of clover-roots left in the soil to the depth of six inches. It may be well to tabulate the figures obtained:

Clover-Roots, in Six Inches of Soil, Per Acre.

------+--------------------------------+---------+---------+---------- Air-dry Nitrogen Phosphoric roots, in roots, acid in per acre. per acre. roots, per acre.

------+--------------------------------+---------+---------+---------- 1st Year. No. 1. Good Clover from brow 7705 100 of the hill " 2. Bad " " " 3920 31 " " " 2d Year. " 3. Good Clover from bottom 7569 61 27 of the field " 4. Thin " " brow 8064 66 " " hill " 5. Heavy crop of first-year clover mown twice for hay 24 " 6. Heavy crop of first-year clover mown once for hay, 51 and then for seed " 7. German experiment, 10 inches deep 8921 191 74 ------+--------------------------------+---------+---------+----------

I have not much confidence in experiments of this kind. It is so easy to make a little mistake; and when you take only a square foot of land, as was the case with Nos. 5 and 6, the mistake is multiplied by 43,560.

Still, I give the table for what it is worth.

Nos. 1 and 2 are from a one-year-old crop of clover. The field was a calcareous clay soil. It was somewhat hilly; or, perhaps, what we here, in Western New York, should call "rolling land." The soil on the brow of the hill, "was very stony at a depth of four inches, so that it could only with difficulty be excavated to six inches, when the bare limestone-rock made its appearance."

A square yard was selected on this shallow soil, where the clover was good; and the roots, air-dried, weighed at the rate of 7,705 lbs. per acre, and contained 100 lbs. of nitrogen. A few yards distance, on the same soil, where the clover was bad, the acre of roots contained only 31 lbs. of nitrogen per acre.

So far, so good. We can well understand this result. Chemistry has little to do with it. There was a good stand of clover on the one plot, and a poor one on the other. And the conclusion to be drawn from it is, that it is well worth our while to try to secure a good catch of clover.

"But, suppose," said the Doctor, "No. 2 had happened to have been pastured by sheep, and No. 1 allowed to go to seed, what magic there would have been in the above figures!"

Nos. 3 and 4 are from the same field, the second year. No. 4 is from a square yard of thin clover on the brow of the hill, and No. 3, from the richer, deeper land towards the bottom of the hill.

There is very little difference between them. The roots of thin clover from the brow of the hill, contain five lbs. more nitrogen per acre, than the roots on the deeper soil.

If we can depend on the figures, we may conclude that on our poor stony "knolls," the clover has larger and longer roots than on the richer parts of the field. We know that roots will run long distances and great depths in search of food and water.

Nos. 5 and 6 are from a heavy crop of one-year-old clover. No. 5 was mown twice for hay, producing, in the two cuttings, over four tons of hay per acre. No. 6 was in the same field, the only difference being that the clover, instead of being cut the second time for hay, was allowed to stand a few weeks longer to ripen its seed. You will see that the latter has more roots than the former.

There are 24 lbs. of nitrogen per acre in the one case, and 51 lbs. in the other. How far this is due to difference in the condition of the land, or to the difficulties in the way of getting out all the roots from the square yard, is a matter of conjecture.

Truth to tell, I have very little confidence in any of these figures. It will be observed that I have put at the bottom of the table, the result of an examination made in Germany. In this case, the nitrogen in the roots of an acre of clover, amounted to 191 lbs. per acre. If we can depend on the figures, we must conclude that there were nearly eight times as much clover-roots per acre in the German field, as in the remarkably heavy crop of clover in the English field No. 5.

"Yes," said the Deacon, "but the one was 10 inches deep, and the other only six inches deep; and besides, the German experiment includes the 'stubble' with the roots."

The Deacon is right; and it will be well to give the complete table, as published in the _American Agriculturist_:

Table Showing the Amount of Roots and Stubble Left Per Acre by Different Crops, and the Amount of Ingredients Which They Contain Per Acre.

-------------------------+---------------+------------+--------------- No. of lbs. of stubble & roots No. of lbs.

(dry) per acre No. of lbs. of ash, free to a depth of of Nitrogen from carbonic 10 inches. per acre. acid, per acre.

-------------------------+---------------+------------+--------------- Lucern (4 years old) 9,678.1 136.4 1,201.6 Red-Clover (1 year old,) 8,921.6 191.6 1,919.9 Espa.r.s.ette (3 years old) 5,930.9 123.2 1,023.4 Rye 5,264.6 65.3 1,747.8 Swedish Clover 5,004.3 102.3 974.6 Rape 4,477. 56.5 622.3 Oats 3,331.9 26.6 1,444.7 Lupine 3,520.9 62.2 550.

Wheat 3,476. 23.5 1,089.8 Peas 3,222.5 55.6 670.7 Serradella 3,120.1 64.8 545.6 Buckwheat 2,195.6 47.9 465.5 Barley 1,991.4 22.8 391.1 -------------------------+---------------+------------+---------------

Contents of the Ashes, in Pounds, Per Acre.