Chapter 52

FERMENTING MANURE.

Dr. Vœlcker placed 2,838 lbs. of fresh mixed manure in a heap Nov. 3, 1854, and the next spring, April 30, it weighed 2,026 lbs., a shrinkage in weight of 28.6 per cent. In other words 100 tons of such manure would be reduced to less than 71½ tons.

The heap was weighed again, August 23d, and contained 1,994 lbs. It was again weighed Nov. 15, and contained 1,974 lbs.

The following table shows the composition of the heap when first put up, and also at the three subsequent periods:

Table Showing Composition of the Whole Heap; Fresh Farm-Yard Manure (No. I.) Exposed--Expressed in Lbs.

----------------------------+---------+---------+---------+--------- |When put |April 30,|Aug. 23, |Nov. 15, |up, Nov. |1855. |1855. |1855. |3, 1854. | | | ----------------------------+---------+---------+---------+--------- Weight of manure in lbs. | 2,838 | 2,026 | 1,994 | 1,974 Amt. of water in the manure | 1,877.9 | 1,336.1 | 1,505.3 | 1,466.5 Amt. of dry matter in the | | | | manure | 960.1 | 689.9 | 488.7 | 507.5 Consisting of-- | | | | Soluble organic matter { | 70.38| 86.51| 58.83| 54.04 Soluble mineral matter { | 43.71| 57.88| 39.16| 36.89 Insoluble organic matter { | 731.07| 389.74| 243.22| 214.92 Insoluble mineral matter { | 114.92| 155.77| 147.49| 201.65 | --------| --------| --------| -------- | 960.1 | 689.9 | 488.7 | 507.5 | | | | Containing nitrogen | 4.22| 6.07| 3.76| 3.65 Equal to ammonia | 5.12| 7.37| 4.56| 4.36 Containing nitrogen | 14.01| 12.07| 9.38| 9.38 Equal to ammonia | 17.02| 14.65| 11.40| 11.39 | --------| --------| --------| -------- Total amount of nitrogen in | | | | manure | 18.23| 18.14| 13.14| 13.03 Equal to ammonia | 22.14| 22.02| 15.96| 15.75 | | | | The manure contains ammonia | | | | in free state | .96| .15| .20| .11 The manure contains ammonia | | | | in form of salts, easily | | | | decomposed by quicklime | 2.49| 1.71| .75| .80 Total amount of organic | | | | matters | 801.45| 476.25| 302.05| 268.96 Total amount of mineral | | | | matters | 158.15| 213.65| 186.65| 238.54 ----------------------------+---------+---------+---------+---------

“It will be remarked,” says Dr. Vœlcker, “that in the first experimental period, the fermentation of the dung, as might have been expected, proceeded most rapidly, but that, notwithstanding, very little nitrogen was dissipated in the form of volatile ammonia; and that on the whole, the loss which the manure sustained was inconsiderable when compared with the enormous waste to which it was subject in the subsequent warmer and more rainy seasons of the year. Thus we find at the end of April very nearly the same amount of nitrogen which is contained in the fresh; whereas, at the end of August, 27.9 per cent of the total nitrogen, or nearly one-third of the nitrogen in the manure, has been wasted in one way or the other.

“It is worthy of observation,” continues Dr. Vœlcker, “that, during a well-regulated fermentation of dung, the loss in intrinsically valuable constituents is inconsiderable, and that in such a preparatory process the _efficacy of the manure becomes greatly enhanced_. For certain purposes fresh dung can never take the place of well-rotted dung. * * The farmer will, therefore, always be compelled to submit a portion of home-made dung to fermentation, and will find satisfaction in knowing that this process, when well regulated, is not attended with any serious depreciation of the value of the manure. In the foregoing analyses he will find the direct proof that as long as heavy showers of rain are excluded from manure-heaps, or the manure is kept in water-proof pits, the most valuable fertilizing matters are preserved.”

This experiment of Dr. Vœlcker proves conclusively that manure can be kept in a rapid state of fermentation for six months during winter, with little loss of nitrogen or other fertilizing matter.

During fermentation a portion of the insoluble matter of the dung becomes soluble, and if the manure is then kept in a heap exposed to rain, there is a great loss of fertilizing matter. This is precisely what we should expect. We ferment manure to make it more readily available as plant-food, and when we have attained our object, the manure should be applied to the land. We keep winter apples in the cellar until they get ripe. As soon as they are ripe, they should be eaten, or they will rapidly decay. This is well understood. And it should be equally well known that manure, after it has been fermenting in a heap for six months, cannot safely be kept for another six months exposed to the weather.

The following table shows the composition of 100 lbs. of the farm-yard manure, at different periods of the year:

Composition of 100 Lbs. of Fresh Farm-Yard Manure (No. I.) Exposed in Natural State, at Different Periods of the Year.

-------------------------+--------+--------+--------+--------+-------- |When put|Feb. 14,|Apr. 30,|Aug. 23,|Nov. 15, |up, Nov.|1855. |1855. |1855. |1855. |3, 1854.| | | | -------------------------+--------+--------+--------+--------+-------- Water | 66.17 | 69.83 | 65.95 | 75.49 | 74.29 Soluble organic matter | 2.48 | 3.86 | 4.27 | 2.95 | 2.74 Soluble inorganic matter | 1.54 | 2.97 | 2.86 | 1.97 | 1.87 Insoluble organic matter | 25.76 | 18.44 | 19.23 | 12.20 | 10.89 Insoluble mineral matter | 4.05 | 4.90 | 7.69 | 7.39 | 10.21 +--------+--------+--------+--------+-------- | 100.00 |100.00 |100.00 |100.00 |100.00 Containing nitrogen | .149| .27 | .30 | .19 | .18 Equal to ammonia | .181| .32 | .36 | .23 | .21 Containing nitrogen | .494| .47 | .59 | .47 | .47 Equal to ammonia | .599| .57 | .71 | .62 | .57 Total amount of nitrogen | .643| .74 | .89 | .66 | .65 Equal to ammonia | .780| .89 | 1.07 | .85 | .78 Ammonia in a free state | .034| .049 | .008 | .010 | .006 Ammonia in form of salts | | | | | easily decomposed | | | | | by quicklime | .088| .064 | .085 | .038 | .041 Total amt. of organic | 28.24 | 22.30 | 23.50 | 15.15 | 13.63 matter | | | | | Total amt. of mineral | 5.59 | 7.87 | 10.55 | 9.36 | 12.08 substances | | | | | -------------------------+--------+--------+--------+--------+--------

It will be seen that two-thirds of the fresh manure is water. After fermenting in an exposed heap for six months, it still contains about the same _percentage_ of water. When kept in the heap until August, the percentage of water is much greater. Of four tons of such manure, three tons are water.

Of _Nitrogen_, the most valuable ingredient of the manure, the fresh dung, contained 0.64 per cent; after fermenting six months, it contained 0.89 per cent. Six months later, it contained 0.65 per cent, or about the same amount as the fresh manure.

Of mineral matter, or ash, this fresh farm-yard manure contained 5.59 per cent; of which 1.54 was soluble in water, and 4.05 insoluble. After fermenting in the heap for six months, the manure contained 10.55 per cent of ash, of which 2.86 was soluble, and 7.69 insoluble. Six months later, the soluble ash had decreased to 1.97 per cent.

The following table shows the composition of the manure, at different periods, in the _dry state_. In other words, supposing all the water to be removed from the manure, its composition would be as follows:

Composition of Fresh Farm-Yard Manure (No. I.) Exposed. Calculated Dry.

-------------------------+--------+--------+--------+--------+-------- |When put|Feb. 14,|Apr. 30,|Aug. 23,|Nov. 15, |up, Nov.|1855. |1855. |1855. |1855. |3, 1854.| | | | -------------------------+--------+--------+--------+--------+-------- Soluble organic matter | 7.33 | 12.79 | 12.54 | 12.04 | 10.65 Soluble inorganic matter | 4.55 | 9.84 | 8.39 | 8.03 | 7.27 Insoluble organic matter | 76.15 | 61.12 | 56.49 | 49.77 | 42.35 Insoluble mineral matter | 11.97 | 16.25 | 22.58 | 30.16 | 39.73 +--------+--------+--------+--------+-------- | 100.00 | 100.00 | 100.00 | 100.00 | 100.00 | | | | | Containing nitrogen | .44 | .91 | .88 | .77 | .72 Equal to ammonia | .53 | 1.10 | 1.06 | .93 | .88 Containing nitrogen | 1.46 | 1.55 | 1.75 | 1.92 | 1.85 Equal to ammonia | 1.77 | 1.88 | 2.12 | 2.33 | 2.24 Total amount of nitrogen | 1.90 | 2.46 | 2.63 | 2.69 | 2.57 Equal to ammonia | 2.30 | 2.98 | 3.18 | 3.26 | 3.12 Ammonia in free state | .10 | .062| .023| .041| .023 Ammonia in form of salts | | | | | easily decomposed by | | | | | quicklime | .26 | .212| .249| .154| .159 Total amount of organic | | | | | matter | 83.48 | 73.91 | 69.03 | 61.81 | 53.00 Total amount of mineral | | | | | substances | 16.52 | 26.09 | 30.97 | 38.19 | 47.00 -------------------------+--------+--------+--------+--------+--------

“A comparison of these different analyses,” says Dr. Vœlcker, “points out clearly the changes which fresh farm-yard manure undergoes on keeping in a heap, exposed to the influence of the weather during a period of twelve months and twelve days.

“1. It will be perceived that the proportion of organic matter steadily diminishes from month to month, until the original percentage of organic matter in the dry manure, amounting to 83.48 per cent, becomes reduced to 53 per cent.

“2. On the other hand, the total percentage of mineral matter rises as steadily as that of the organic matter falls.

“3. It will be seen that the loss in organic matter affects the percentage of insoluble organic matters more than the percentage of soluble organic substances.

“4. The percentage of soluble organic matters, indeed, increased considerably during the first experimental period; it rose, namely, from 7.33 per cent to 12.79 per cent. Examined again on the 30th of April, very nearly the same percentage of soluble organic matter, as on February the 14th, was found. The August analysis shows but a slight decrease in the percentage of soluble organic matters, while there is a decrease of 2 per cent of soluble organic matters when the November analysis is compared with the February analysis.

“5. The soluble mineral matters in this manure rise or fall in the different experimental periods in the same order as the soluble organic matters. Thus, in February, 9.84 per cent of soluble mineral matters were found, whilst the manure contained only 4.55 per cent, when put up into a heap in November, 1854. Gradually, however, the proportion of soluble mineral matters again diminished, and became reduced to 7.27 per cent, on the examination of the manure in November, 1855.

“6. A similar regularity will be observed in the percentage of nitrogen contained in the soluble organic matters.

“7. In the insoluble organic matters, the percentage of nitrogen regularly increased from November, 1854, up to the 23d of August, notwithstanding the rapid diminution of the percentage of insoluble organic matter. For the last experimental period, the percentage of nitrogen in the insoluble matter is nearly the same as on August 23d.

“8. With respect to the total percentage of nitrogen in the fresh manure, examined at different periods of the year, it will be seen that the February manure contains about one-half per cent more of nitrogen than the manure in a perfectly fresh state. On the 30th of April, the percentage of nitrogen again slightly increased; on August 23d, it remained stationary, and had sunk but very little when last examined on the 15th of November, 1855.

“This series of analyses thus shows that fresh farm-yard manure rapidly becomes more soluble in water, but that this desirable change is realized at the expense of a large proportion of organic matters. It likewise proves, in an unmistakable manner, that there is no advantage in keeping farm-yard manure for too long a period; for, after February, neither the percentage of soluble organic, nor that of soluble mineral matter, has become greater, and the percentage of nitrogen in the manure of April and August is only a very little higher than in February.”

“Before you go any further,” said the Deacon, “answer me this question: Suppose I take five tons of farm-yard manure, and put it in a heap on the 3d of November, tell me, 1st, what that heap will contain when first made; 2d, what the heap will contain April 30th; and, 3d, what the heap will contain August 23d.”

Here is the table:

Contents of a Heap of Manure at Different Periods, Exposed to Rain, etc.

-------------------------------+---------+---------+---------+-------- |When |Apr. 30. |Aug. 23. |Nov. 15. |put up, | | | |Nov. 3. | | | -------------------------------+---------+---------+---------+-------- Total weight of manure in heap |10,000 | 7,138 | 7,025 | 6,954 Water in the heap of manure | 6,617 | 4,707 | 5,304 | 5,167 Total organic matter | 2,824 | 1,678 | 1,034 | 947 Total inorganic matter | 559 | 753 | 657 | 840 Total nitrogen in heap | 64.3 | 63.9 | 46.3 | 46.0 Total soluble organic matter | 248 | 305 | 207 | 190 Total insoluble organic matter | 2,576 | 1,373 | 857 | 757 Soluble mineral matter | 154 | 204 | 138 | 130 Insoluble mineral matter | 405 | 549 | 519 | 710 Nitrogen in soluble matter | 14.9 | 21.4 | 13.2 | 12.9 Nitrogen in insoluble matter | 49.4 | 42.5 | 33.1 | 33.1 -------------------------------+---------+---------+---------+--------

The Deacon put on his spectacles and studied the above table carefully for some time. “That tells the whole story,” said he, “you put five tons of fresh manure in a heap, it ferments and gets warm, and nearly one ton of water is driven off by the heat.”

“Yes,” said the Doctor, “you see that over half a ton (1,146 lbs.) of dry organic matter has been slowly burnt up in the heap; giving out as much heat as half a ton of coal burnt in a stove. But this is not all. The manure is cooked, and steamed, and softened by the process. The organic matter burnt up is of no value. There is little or no loss of nitrogen. The heap contained 64.3 lbs. of nitrogen when put up, and 63.9 lbs. after fermenting six months. And it is evident that the manure is in a much more active and available condition than if it had been applied to the land in the fresh state. There was 14.9 lbs. of nitrogen in a soluble condition in the fresh manure, and 21.4 lbs. in the fermented manure. And what is equally important, you will notice that there is 154 lbs. of soluble ash in the heap of fresh manure, and 204 lbs. in the heap of fermented manure. In other words, 50 lbs. of the insoluble mineral matter had, by the fermentation of the manure, been rendered soluble, and consequently immediately available as plant-food. This is a very important fact.”

The Doctor is right. There is clearly a great advantage in fermenting manure, provided it is done in such a manner as to prevent loss. We have not only less manure to draw out and spread, but the plant-food which it contains, is more soluble and active.

The table we have given shows that there is little or no loss of valuable constituents, even when manure is fermented in the open air and exposed to ordinary rain and snows during an English winter. But it also shows that when the manure has been fermented for six months, and is then turned and left exposed to the rain of spring and summer, the loss is very considerable.

The five tons (10,000 lbs.,) of fresh manure placed in a heap on the 3d of November, are reduced to 7,138 lbs. by the 30th of April. Of this 4,707 lbs. is water. By the 23d of August, the heap is reduced to 7,025 lbs., of which 5,304 lbs. is water. There is nearly 600 lbs. more water in the heap in August than in April.

Of total nitrogen in the heap, there is 64.3 lbs. in the fresh manure, 63.9 lbs. in April, and only 46.3 lbs. in August. This is a great loss, and there is no compensating gain.

We have seen that, when five tons of manure is fermented for six months, in winter, the nitrogen in the soluble organic matter is increased from 14.9 lbs. to 21.4 lbs. This is a decided advantage. But when the manure is kept for another six months, this soluble nitrogen is decreased from 21.4 lbs. to 13.2 lbs. We lose over 8 lbs. of the most active and available nitrogen.

And the same remarks will apply to the valuable soluble mineral matter. In the five tons of fresh manure there is 154 lbs. of soluble mineral matter. By fermenting the heap six months, we get 204 lbs., but by keeping the manure six months longer, the soluble mineral matter is reduced to 138 lbs. We lose 66 lbs. of valuable soluble mineral matter.

By fermenting manure for six months in winter, we greatly improve its condition; by keeping it six months longer, we lose largely of the very best and most active parts of the manure.