Talks on Manures Part 43

In this case, as before, the land was a two-year-old clover-sod. It was plowed about the first of May, and harrowed until it was in a good mellow condition. The potatoes were planted in hills 3 feet apart each way. The following table shows the manures used and the yield of potatoes per acre.

Experiments on Potatoes at Moreton Farm.

P. Number of Plot.

Y/A Yield of Potatoes per acre, in bushels.

I/A Increase of Potatoes per acre, in bushels, caused by manure.

---+-----------------------------------------------------+-----+---- Description of Manures Used, and Quant.i.ties P. Applied per Acre. Y/A I/A ---+-----------------------------------------------------+-----+---- 1. No manure 95 2. 150 lbs. sulphate of ammonia 140 45 3. 300 lbs. superphosphate of lime 132 37 4. 150 lbs. sulphate of ammonia, and 300 lbs. superphosphate of lime 179 84 5. 400 lbs. of unleached wood-ashes 100 5 6. 100 lbs. plaster, (gypsum, or sulphate of lime,) 101 6 7. 400 lbs. unleached wood-ashes and 100 lbs. plaster 110 15 8. 400 lbs. unleached wood-ashes, 150 lbs. sulphate of ammonia and 100 lbs. plaster 109 14 9. 300 lbs. superphosphate of lime, 150 lbs. sulphate of ammonia and 400 lbs. unleached wood-ashes 138 43 ---+-----------------------------------------------------+-----+----

The superphosphate of lime was made expressly for experimental purposes, from calcined bones, ground fine, and mixed with sulphuric acid in the proper proportions to convert all the phosphate of lime of the bones into the soluble superphosphate. It was a purely mineral article, free from ammonia and other organic matter. It cost about two and a half cents per pound.

The manures were deposited in the hill, covered with an inch or two of soil, and the seed then planted on the top. Where superphosphate of lime or sulphate of ammonia was used in conjunction with ashes, the ashes were first deposited in the hill and covered with a little soil, and then the superphosphate or sulphate of ammonia placed on the top and covered with soil before the seed was planted. Notwithstanding this precaution, the rain washed the sulphate of ammonia into the ashes, and decomposition, with loss of ammonia, was the result. This will account for the less yield on plot 8 than on plot 2. It would have been better to have sown the ashes broadcast, but some previous experiments with Peruvian guano on potatoes indicated that it was best to apply guano in the hill, carefully covering it with soil to prevent it injuring the seed, than to sow it broadcast. It was for this reason, and for the greater convenience in sowing, that the manures were applied in the hill.

The ash of potatoes consists of about 50 per cent of potash, and this fact has induced many writers to recommend ashes as a manure for this crop. It will be seen, however, that in this instance, at least, they have very little effect, 400 lbs. giving an increase of only five bushels per acre. One hundred pounds of plaster per acre gave an increase of six bushels. Plaster and ashes combined, an increase per acre of 15 bushels.

One fact is clearly brought out by these experiments: that this soil, which has been under cultivation without manure for many years, is not, relatively to other const.i.tuents of crops, deficient in potash. Had such been the case, the sulphate of ammonia and superphosphate of lime--manures which contain no potash--would not have give a an increase of 84 bushels of potatoes per acre. There was sufficient potash in the soil, in an available condition, for 179 bushels of potatoes per acre; and the reason why the soil without manure produced only 95 bushels per acre, was owing to a deficiency of ammonia and phosphates.

Since these experiments were made, Dr. Vlcker and others have made similar ones in England. The results on the whole all point in one direction. They show that the manures most valuable for potatoes are those rich in nitrogen and phosphoric acid, and that occasionally potash is also a useful addition.

"There is one thing I should like to know," said the Doctor. "Admitting that nitrogen and phosphoric acid and potash are the most important elements of plant-food, how many bushels of potatoes should we be likely to get from a judicious application of these manures?"

"There is no way," said I, "of getting at this with any degree of certainty. The numerous experiments that have been made in England seem to show that a given quant.i.ty of manure will produce a larger _increase_ on poor land than on land in better condition."

In England potatoes are rarely if ever planted without manure, and the land selected for this crop, even without manure, would usually be in better condition than the average potato land of this section, and consequently a given amount of manure, applied to potatoes here, would be likely to do more good, up to a certain point, than the same amount would in England.

Let us look at some of the experiments that have been made in England:--

In the Transactions of the Highland and Agricultural Society of Scotland for 1873 is a prize essay on "Experiments upon Potatoes, with Potash Salts, on Light Land," by Charles D. Hunter, F.C.S., made on the farm of William Lawson, in c.u.mberland. Mr. Hunter "was charged with the manuring of the farm and the purchasing of chemical manures to the annual value of 2,000," or say $10,000.

"Potatoes," says Mr. Hunter, "were largely grown on the farm, and in the absence of a sufficiency of farm-yard manure, potash naturally suggested itself as a necessary const.i.tuent of a chemical potato-manure. The soil was light and gravelly, with an open subsoil, and the rainfall from 29 to 38 inches a year."

The first series of experiments was made in 1867. The following are some of the results:-- Bushels per acre.

No manure 221 4 cwt. mineral superphosphate 225 4 cwt. mineral superphosphate and } 240 4 cwt. of muriate of potash } 15 tons farm-yard manure 293

"That does not say much for potash and superphosphate," said the Deacon.

"The superphosphate only produced four bushels more than the no manure, and the potash and superphosphate only fifteen bushels more than the superphosphate alone."

It may be worth while mentioning that one of the experimental plots this year was on a head-land, "where the cattle frequently stand for shelter." This plot was dressed with only eight and a half tons of manure, and the crop was over 427 bushels per acre, while a plot alongside, without manure, produced only 163 bushels per acre.

"That shows the importance," said the Deacon, "of planting potatoes on rich land, rather than to plant on poor land and try to make it rich by applying manure directly to the crop."

The following are some of the results in 1868:

Bushels per acre.

1. No manure 232 {4 cwt. superphosphate } 2. {2 " muriate of potash } 340 {2 " sulphate of ammonia } 3. 20 tons farm-yard manure 342 4. {4 cwt. superphosphate } 274 {4 " muriate of potash }

"Here again," said the Doctor, "superphosphate and potash alone give an increase of only forty-two bushels per acre, while on plot 2, where two hundred weight of muriate of potash is subst.i.tuted by two hundred weight of sulphate of ammonia, the increase is 108 bushels per acre. It certainly looks as though a manure for potatoes, so far as yield is concerned, should be rich in available nitrogen."

The following are some of the results in 1869:

Bushels per acre.

1. No manure 176

2. {4 cwt. superphosphate } { " sulphate of magnesia } 306 {2 " muriate of potash } {2 " sulphate of ammonia }

3. 4 cwt. superphosphate 189

4. {4 cwt. superphosphate } 201 {2 " sulphate of ammonia }

5. {4 cwt. superphosphate } {2 " muriate of potash } 340 {2 " sulphate of ammonia. }

6. {4 cwt. superphosphate } 249 {2 " muriate of potash }

"This is a very interesting experiment," said the Doctor.

"Superphosphate alone gives an increase of thirteen bushels.

Superphosphate and potash an increase of seventy-three bushels. The potash, therefore, gives an increase of sixty bushels. Superphosphate _and_ ammonia give twelve bushels more than superphosphate alone, and the reason it does not produce a better crop is owing to a deficiency of potash. When this is supplied the ammonia gives an increase (plots 5 and 6) of ninety-one bushels per acre."

In 1870 the above experiments were repeated on the same land, with the same general results.

In 1871 some experiments were made on a sharp, gravelly soil, which had been over-cropped, and was in poor condition. The following are the results:--

Bushels per acre.

1. {9 cwt. superphosphate } 186 {3 " sulphate of ammonia }

2. {9 cwt. superphosphate } {3 " muriate of potash } 204 {3 " sulphate of ammonia }

3. No manure 70

4. {9 cwt. superphosphate } {3 " muriate of potash } 205 {3 " sulphate of ammonia }

5. 20 tons farm-yard manure 197

"On this poor soil," said the Doctor, "the ammonia and superphosphate gave an increase of 116 bushels per acre; and 3 hundred weight of muriate of potash an increase, on one plot, of eighteen bushels, and on the other nineteen bushels per acre."

In the same year, 1871, another set of experiments was made on a better and more loamy soil, which had been in gra.s.s for several years. In 1869 it was sown for hay, and in 1870 was broken up and sown to oats, and the next spring planted with potatoes. The following are some of the results:

Bushels per acre.

{6 cwt. superphosphate } 1. {2 " muriate of potash } 321 {2 " sulphate of ammonia }

2. {6 cwt. superphosphate } 296 {2 " sulphate of ammonia }

3. No manure 252

4. {6 cwt. superphosphate } 311 {2 " muriate of potash }

5. 2 cwt. sulphate of ammonia 238