Chapter XXVI — The Rothamsted Experiments — Manures and the Principles of Manuring by Charles Morton Aikman

Chapter XXVI The Rothamsted Experiments

Reference has been so repeatedly made in the preceding pages to the Rothamsted experiments on manures, that it may form a fitting conclusion to the present treatise to give a short account of these famous experiments.

In describing these experiments, the author has remarked elsewhere 256 “that, in respect of their wide scope, dealing as they have done with almost every department of farming, the elaborate care and accuracy with which they have been carried out, the length of time they have been in progress, and, lastly, in respect of the important bearing their results have had on agricultural practice, these famous experiments may be justly described as unrivalled by any other similar ones.”

Started on a small scale in 1837 by Sir John (then Mr) Lawes, they were placed on a systematic basis in 1843, in which year Sir John Lawes associated with himself Sir (then Dr) J. Henry Gilbert. They have thus been in progress for a period of fifty years—a fact which was celebrated a few months ago by the presentation of numerous congratulatory addresses from various learned and agricultural societies to the distinguished investigators, and the erection of a memorial granite slab at Rothamsted. What increases the feeling of gratitude due to Sir John Lawes by the agricultural community, is the fact that the entire expense of conducting these experiments has been borne by himself, and he has further most generously handed over to the nation a large sum of money and a certain area of land for carrying them on in perpetuity.

Nature of Experiments on Crops and Manures.

The earliest systematic experiments were on turnips, and since then almost every common crop has been experimented on. Table I. (p. 562) is a list of the different experiments, with their duration, area, and number of plots.

Soil of Rothamsted.

Before describing the more striking results of these experiments, it may be advisable to say that the elevation of the land at Rothamsted is about 400 feet above sea-level; that the average rainfall is about 28 inches per annum; and that the surface-soil is a heavy loam, and the subsoil a stiff clay, resting on chalk.

TABLE I.—List of Rothamsted Field Experiments.

Crops.	Duration.	Area.	Plots.
	Years.	Acres.
Wheat (various manures)	50	11	34 (or 37)
Wheat alternated with fallow	42	1	2
Wheat (varieties)	15	4-8	about 20
Barley (various manures)	42	4-1/4	29
Oats (various manures)	10¹	0-3/4	6
Beans (various manures)	32²	1-1/4	10
Beans (various manures)	27³	1	5
Beans, alternated with wheat	28⁴	1	10
Clover (various manures)	29⁵	3	18
Various leguminous plants	15	3	18
Turnips (various manures)	28⁶	8	40
Sugar-beet (various manures)	5	8	41
Mangel-wurzel (various manures)	18	8	41
Total root crops	51
Potatoes (various manures)	18	2	10
Rotation (various manures)	46	3	12
Permanent grass (various manures)	38	7	22
¹Including one year fallow.
²Including one year wheat and five years fallow.
³Including four years fallow.
⁴Including two years fallow.
⁵Clover, twelve times sown (first in 1848), eight yielding crops, but four of these very small, one year wheat, five years barley, twelve years fallow.
⁶Including barley without manure three years (eleventh, twelfth, and thirteenth seasons).

Wheat Experiments.

The first experiments we shall refer to are those on wheat, since they are among the oldest, and their results the most striking of any.

Unmanured Plots.

Wheat has been continuously grown year after year on three plots for fifty years, without the application of any manure whatever.

We shall first give the results of the first eight years as illustrating the effect of season, which accounts for the irregular results obtained. But for the difference in seasons, we should expect to find a steady decrease in the amount of produce; and this is shown in taking the average of groups of years, as we shall do in the next table.

Wheat grown continuously on same Land (unmanured).

Table II.—(a.) Remits of first Eight Years (1844 to 1851).

Year.	Bushels.
1844	15
1845	23-1/4
1846	18
1847	16-7/8
1848	14-3/4
1849	19-1/4
1850	15-7/8
1851	15-7/8
Average of 8 years	17-3/8

Table III.—(b.) Results of subsequent Forty Years (1852 to 1891).

	Grain	Weight per	Straw
	(bushels).	bushel.	(cwts.)
20 years (1852-1871)	14-1/2	57-5/8	13
20 years (1872-1891)	11-1/2	58-3/4	8-5/8
40 years (1852-1891)	13	58-1/4	10-5/8
49th season (1891)	9-3/8	59-1/2	7-1/2

It is interesting to notice the comparatively slight decrease which has taken place in the yield of wheat during these fifty years. With such wide variations, due to season, it is extremely difficult, as Sir J. Henry Gilbert has pointed out, to estimate rate of decline due to exhaustion. Excluding the very bad seasons, this may be reckoned at from one-fourth to one-third of a bushel per acre per annum. The return of the first year is 15 bushels, while the yield of the forty-ninth season is 9-3/8 bushels. The average of the returns obtained during these fifty years is really in excess of the average yield of the principal wheat-producing countries in the world. This is truly a most astounding result.

The next experiments we shall describe are those on the influence of farmyard manure on the wheat crop when grown continuously.

TABLE IV.—Wheat grown continuously with Farmyard Manure (14 tons per annum).

		Weight per	Straw
	Bushels.	bushel (lb.)	(cwts.)
8 years (1844-1852)	28	—	—
20 years (1852-1871)	35-7/8	60	33-7/8
20 years (1872-1891)	33-1/2	60-3/8	31-3/8
40 years (1852-1891)	34-7/8	60-1/4	32-5/8

It will be seen from the above results, which contain merely a selection from a very much greater number of experiments, that farmyard manure gives as good an average over the forty years as most of the artificial mixtures do. That this is due to the nitrogen it contains, is strikingly illustrated by the fact that mixed mineral manures alone give less than half the return, and also by the fact that ammonia salts alone give a return twice as great as mineral mixtures; while, lastly, the mixture of mineral manures and ammonia salts gives but a slight increase over that obtained with ammonia salts alone.

The remaining results, selected from a much larger number, need no comment, and we shall give them in tabular form.

Table V.—Wheat grown continuously with Artificial Manures, Farmyard Manure, and Unmanured.

Average of Forty Years (1852-91).

	Produce per Acre—Average per Annum.
	Dressed grain.
Manures per Acre per Annum.	Quantity.
	20 years,	20 years,	40 years,
	1852-71.	1872-91.	1852-91.
	bush.	bush.	bush.
Farmyard manure, 14 tons per annum since 1843	35-7/8	33-1/2	34-7/8
Unmanured continuously	14-1/2	11-1/2	13
Mixed mineral manures¹ and 3-1/2 cwt. superphosphate	17	12-7/8	15
Mixed mineral manures, 3-1/2 cwt. superphosphate, 200 lb. ammonium salts	26-1/2	21-3/4	24-1/8
Mixed mineral manures and 3-1/2 cwt. superphosphate, 600 lb. ammonium salts	38-1/4	34-3/4	36-1/2
Mixed mineral manures, 3-1/2 cwt. superphosphate, 275 lb. nitrate of soda	36-7/8	34	35-3/8
275 lb. nitrate of soda	26	19-3/8	22-3/4
400 lb. ammonium salts every year since 1845	22-1/2	19	22-1/2
400 lb. ammonium salts, 3-1/2 cwt. superphosphate	28	22-1/4	25-1/8
Mineral manure, 3-1/2 cwt. superphosphate, 400 lb. ammonium salts in autumn.	31-5/8	29-1/2	30-1/2
¹By the term mixed mineral manures is meant a mixture of mineral fertilisers, not including phosphates.

TABLE V.—continued

	Produce per Acre—Average per Annum.
	Dressed grain.
Manures per Acre per Annum.	Weight per bushel.
	20 years,	20 years,	40 years,
	1852-71.	1872-91.	1852-91.
	lb.	lb.	lb.
Farmyard manure, 14 tons per annum since 1843	60	60-3/8	60-1/4
Unmanured continuously	57-5/8	58-3/4	58-1/4
Mixed mineral manures and 3-1/2 cwt. superphosphate	58-7/8	59	58-7/8
Mixed mineral manures, 3-1/2 cwt. superphosphate, 200 lb. ammonium salts	59-3/8	60	59-5/8
Mixed mineral manures and 3-1/2 cwt. superphosphate, 600 lb. ammonium salts	59	60	59-1/2
Mixed mineral manures, 3-1/2 cwt. superphosphate, 275 lb. nitrate of soda	58-3/8	59-5/8	59
275 lb. nitrate of soda	56-5/8	56-5/8	56-5/8
400 lb. ammonium salts every year since 1845	58	57-3/8	57-5/8
400 lb. ammonium salts, 3-1/2 cwt. superphosphate	57-3/8	58	57-5/8
Mineral manure, 3-1/2 cwt. superphosphate, 400 lb. ammonium salts in autumn	59-1/2	60	59-3/4

TABLE V.—continued

	Produce per Acre—Average per Annum.
Manures per Acre per Annum.	Total straw.
	20 years,	20 years,	40 years,
	1852-71.	1872-91.	1852-91.
	cwt.	cwt.	cwt.
Farmyard manure, 14 tons per annum since 1843	33-7/8	31-3/8	32-5/8
Unmanured continuously	13	8-5/8	10-5/8
Mixed mineral manures and 3-1/2 cwt. superphosphate	15	9-3/4	12-3/8
Mixed mineral manures, 3-1/2 cwt. superphosphate, 200 lb. ammonium salts	24-1/2	19-1/8	21-7/8
Mixed mineral manures and 3-1/2 cwt. superphosphate, 600 lb. ammonium salts	41-3/8	39-5/8	40-1/2
Mixed mineral manures, 3-1/2 cwt. superphosphate, 275 lb. nitrate of soda	41-1/2	37-3/4	39-5/8
275 lb. nitrate of soda	28-1/4	18-1/2	23-3/8
400 lb. ammonium salts every year since 1845	24-3/4	16-1/4	20-1/2
400 lb. ammonium salts, 3-1/2 cwt. superphosphate	26-3/8	21	23-3/4
Mineral manure, 3-1/2 cwt. superphosphate, 400 lb. ammonium salts in autumn	31-1/4	28-3/8	29-3/4

TABLE VI.—Experiments on the Growth of Barley for Forty Years, 1852-91.

	Produce per Acre—Average per Annum.
	Dressed grain.
Manures per Acre per Annum.	Quantity.
	20 years,	20 years,	40 years,
	1852-71.	1872-91.	1852-91.
	bush.	bush.	bush.
Unmanured continuously	20	25-1/2	16-1/2
3-1/2 cwt. superphosphate of lime	25-1/2	17-3/4	21-3/4
Mixed mineral manures	22-1/2	13-1/2	18
Mixed mineral manures, 3-1/2 cwt. superphosphate	27-1/2	17-1/4	22-3/8
200 lb. ammonium salts	32-1/2	25-5/8	29
200 lb. ammonium salts, 3-1/2 cwt. superphosphate	47	38-1/2	42-3/4
200lb. ammonium salts, mixed mineral manures	35	27-3/4	31-3/8
Manures, 3-1/2 cwt. superphosphate of lime	46-1/4	40-3/4	43-1/2
275 lb. nitrate of soda	37	28-3/8	32-3/4
275 lb. nitrate of soda, 3-1/2 cwt. superphosphate	49-1/4	42-1/4	45-3/4
275 lb. nitrate of soda, mixed mineral manures	37-3/8	29-1/2	33-1/2
275 lb. nitrate of soda, mixed mineral manures, 3-1/2 cwt. superphosphate	49-3/4	41-1/4	45-1/2
1000 lb. rape-cake	45-1/4	37-1/8	41-1/4
1000 lb. rape-cake, 3-1/2 cwt. superphosphate	46-3/4	40	43-3/8
1000 lb. rape-cake, mixed mineral manures	43-5/8	35-5/8	39-1/2
1000 lb. rape-cake, mixed mineral manures, and 3-1/2 cwt. superphosphate	47-3/8	39	43-1/4
Farmyard manure, 14 tons every year	48-1/4	49	48-5/8

TABLE VI.—continued

	Produce per Acre—Average per Annum.
	Dressed grain.
Manures per Acre per Annum.	Weight per bushel.
	20 years,	20 years,	40 years,
	1852-71.	1872-91.	1852-91.
	lb.	lb.	lb.
Unmanured continuously	52-3/8	51-3/4	52
3-1/2 cwt. superphosphate of lime	53-1/4	53	53-1/8
Mixed mineral manures	53	51-7/8	52-1/2
Mixed mineral manures, 3-1/ cwt. superphosphate	53-3/8	52-3/8	53
200 lb. ammonium salts	52-1/8	52	52
200 lb. ammonium salts, 3-1/2 cwt. superphosphate	53-3/8	52-1/4	52-7/8
200 lb. ammonium salts, mixed mineral manures	52-3/4	52-1/2	52-5/8
Manures, 3-1/2 cwt. superphosphate of lime	54	54-1/8	54
275 lb. nitrate of soda	52	52-1/8	52
275 lb. nitrate of soda, 3-1/2 cwt. superphosphate	53-3/8	53-1/4	53-1/4
275 lb. nitrate of soda, mixed mineral manures	52-1/4	52-3/4	52-1/2
275 lb. nitrate of soda, mixed mineral manures, 3-1/2 cwt. superphosphate	53-3/8	54	53-5/8
1000 lb. rape-cake	53-3/4	53-7/8	53-7/8
1000 lb. rape-cake, 3-1/2 cwt. superphosphate	53-7/8	54-3/8	54-1/8
1000 lb. rape-cake, mixed mineral manures	53-3/4	54-1/8	54
1000 lb. rape-cake, mixed mineral manures, and 3-1/2 cwt. superphosphate	53-5/8	54-1/4	53-7/8
Farmyard manure, 14 tons every year	54-3/8	54-1/4	54-1/4

TABLE VI.—continued

	Produce per Acre—Average per Annum.
Manures per Acre per Annum.	Total straw.
	20 years,	20 years,	40 years,
	1852-71.	1872-91.	1852-91.
	cwt.	cwt.	cwt.
Unmanured continuously	11-3/4	6-7/8	9-3/8
3-1/2 cwt. superphosphate of lime	13-3/8	8-1/4	10-3/4
Mixed mineral manures	12-1/4	7	9-5/8
Mixed mineral manures, 3-1/2 cwt. superphosphate	14-3/8	8-3/8	11-3/8
200 lb. ammonium salts	18-1/2	13-1/2	16
200 lb. ammonium salts, 3-1/2 cwt. superphosphate	27-5/8	20-1/8	23-7/8
200 lb. ammonium salts, mixed mineral manures	20-1/4	15-1/8	18
Manures, 3-1/2 cwt. superphosphate of lime	28-1/2	23-3/8	25-7/8
275 lb. nitrate of soda	22-1/8	15-7/8	19
275 lb. nitrate of soda, 3-1/2 cwt. superphosphate	30-1/2	23-3/8	27
275 lb. nitrate of soda, mixed mineral manures	23-7/8	17-1/2	20-3/4
275 lb. nitrate of soda, mixed mineral manures, 3-1/2 cwt. superphosphate	32-3/8	24-1/2	28-1/2
1000 lb. rape-cake	26-7/8	20	23-3/8
1000 lb. rape-cake, 3-1/2 cwt. superphosphate	28-3/8	21-1/2	24-7/8
1000 lb. rape-cake, mixed mineral manures	27-1/8	19-7/8	23-1/2
1000 lb. rape-cake, mixed mineral manures, and 3-1/2 cwt. superphosphate	29-3/4	21-7/8	25-5/8
Farmyard manure, 14 tons every year	28-1/4	29-3/4	29

TABLE VII.

Experiments on the Growth of Oats, 1869-78.

	Average per Annum. 5 years, 1869-73.
	Dressed grain.
Manures per Acre per Annum.		Weight	Total
	Quantity.	per bushel.	straw.
	bush.	lb.	cwt.
Unmanured	19-7/8	33-3/4	10-3/8
200 lb. sulphate potash, 100 lb. sulphate soda, 100 lb. sulphate magnesia, and 3-1/2 cwt. superphosphate of lime	24-1/2	35	13-3/8
400 lb. ammonium salts	47	35-7/8	28-1/2
400 lb. ammonium salts, 200 lb. sulphate potash, 100 lb. sulphate soda, 100 lb. sulphate magnesia, and 3-1/2 cwt. superphosphate	59	37	41-1/8
550 lb. nitrate of soda	47-1/8	35-1/2	27-1/2
550 lb. nitrate of soda, 200 lb. sulphate potash, 100 lb. sulphate soda, 100 lb. sulphate magnesia, and 3-1/2 cwt. superphosphate	57-1/2	35-3/4	35
	Average per Annum. 4 years, 1874-78.
	Bushels.	lb.	cwt.
Unmanured	13-3/4	31-1/4	6
200 lb. sulphate potash, 100 lb. sulphate soda, 100 lb. sulphate magnesia, and 3-1/2 cwt. superphosphate of lime	13-1/8	31-5/8	6-1/8
200 lb. ammonium salts	28-7/8	33-1/4	14-1/8
200 lb. ammonium salts, 200 lb. sulphate potash, 100 lb. sulphate soda, 100 lb. sulphate magnesia, and 3-1/2 cwt. superphosphate	38	35-1/2	20
275 lb. nitrate of soda	26-3/8	31-5/8	11-1/8
275 lb. nitrate of soda, 200 lb. sulphate potash, 100 lb. sulphate soda, 100 lb. sulphate magnesia, and 3-1/2 cwt. superphosphate	28-1/2	34-1/8	14

TABLE VIII.—Experiments on Root Crops: Swedish Turnips.

Fifteen Seasons, 1856-70.¹ Roots and Leaves carted off the Land.

		Series 1.
		Standard manures
		only.
	STANDARD MANURES.
Plots.
		Roots.		Leaves.
		Tons.	cwt.	Tons.	cwt.
1	Farmyard manure, 14 tons	6	4	0	17
2	Farmyard manure, 14 tons, and superphosphate	6	7	0	16
3	Without manure, 1846, and since	0	11	0	3
4	Superphosphate, each year; sulphate potash, soda, and magnesia, 1856-60	2	16	0	8
5	Superphosphate, each year	2	12	0	9
6	Superphosphate, each year; sulphate potash, 1856-60	2	7	0	7
7	Superphosphate, each year; sulphate, potash, and 36-1/2 lb. ammonium salts, 1856-60	2	12	0	7
8	Unmanured 1853, and since; previously part unmanured; part superphosphate	1	3	0	4
Note.—Sulphate of ammonia is estimated to contain 23 per cent ammonia, and muriate of ammonia 27 per cent. Ammonium salts, in each case, equal parts sulphate and muriate of ammonia of commerce; and the mixture is estimated to contain 25 per cent ammonia. The 328 lb. nitric acid (sp. gr. 1.35) mixed with sawdust, and used as a cross-dressing on the plots of Series 2 from 1856-60, were estimated to contain nitrogen = 50 lb. ammonia.
¹The crops of 1859 and 1860 failed, and were ploughed in; but as the manures were applied, and there would be accumulation with the soil for the succeeding crops, the average produce is calculated as for fifteen years—that is, the produce of the thirteen years is, in each case, divided by 15.

TABLE VIII.—continued

		Series 2.				Series 3.
		Standard manures,				Standard manures,
		and cross-dressed with—				and cross-dressed with—
		5 years, 1856-60,				5 years, 1856-60,
		3000 lb. sawdust, and				200 lb. ammonium
		328 lb. nitric acid.				salts.
	STANDARD MANURES.	10 years, 1861-70,				10 years, 1861-70,
		550 lb. nitrate soda.				400 lb. ammonium salts.
Plots.
		Roots.		Leaves.		Roots.		Leaves.
		Tons.	cwt.	Tons.	cwt.	Tons.	cwt.	Tons.	cwt.
1	Farmyard manure, 14 tons	7	9	1	2	8	8	1	4
2	Farmyard manure, 14 tons, and superphosphate	7	13	1	3	8	5	1	5
3	Without manure, 1846, and since	0	19	0	4	0	13	0	3
4	Superphosphate, each year; sulphate potash, soda, and magnesia, 1856-60	5	2	0	16	4	12	0	14
5	Superphosphate, each year	4	13	0	18	3	16	0	15
6	Superphosphate, each year; sulphate potash, 1856-60	4	11	0	14	4	5	0	13
7	Superphosphate, each year; sulphate, potash, and 36-1/2 lb. ammonium salts, 1856-60	4	13	0	14	4	12	0	14
8	Unmanured 1853, and since; previously part unmanured; part superphosphate	1	13	0	5	1	2	0	5

TABLE VIII.—continued

		Series 4.				Series 5.
		Standard manures,				Standard manures,
		and cross-dressed with—				and cross-dressed with—
		5 years, 1856-60,				5 years, 1856-60,
		200 lb. ammonium salts,				3000 lb. sawdust.
		and 3000 lb. sawdust.
	STANDARD MANURES.	10 years, 1861-70,				10 years, 1861-70,
		400 lb. ammonium salts,				2000 lb. rape-cake.
Plots.		and 2000.b. rape-cake.
		Roots.		Leaves.		Roots.		Leaves.
		Tons.	cwt.	Tons.	cwt.	Tons.	cwt.	Tons.	cwt.
1	Farmyard manure, 14 tons	8	16	1	9	8	0	1	4
2	Farmyard manure, 14 tons, and superphosphate	8	14	1	9	7	16	1	2
3	Without manure, 1846, and since	3	6	0	14	3	8	0	13
4	Superphosphate, each year; sulphate potash, soda, and magnesia, 1856-60	6	12	1	5	5	8	0	17
5	Superphosphate, each year	5	16	1	7	5	0	0	19
6	Superphosphate, each year; sulphate potash, 1856-60	6	6	1	2	5	3	0	16
7	Superphosphate, each year; sulphate, potash, and 36-1/2 lb. ammonium salts, 1856-60	6	15	1	4	5	9	0	17
8	Unmanured 1853, and since; previously part unmanured; part superphosphate	3	19	0	18	3	14	0	19

TABLE IX.—Experiments on Mangel-Wurzel.

Average of Sixteen Seasons, 1876-92. Manures per Acre per Annum.

		Series 1.
	STANDARD MANURES.	Standard manures
		only.
Plots.
		Roots.		Leaves.
		Tons.	cwt.	Tons.	cwt.
1	Farmyard manure, 14 tons	16	6	2	17
2	Farmyard manure, 14 tons, and 3-1/2 cwt. superphosphate	4	9	1	8
3	Without manure, 1846, and since	4	9	1	8
4	3-1/2 cwt. superphosphate, 500 lb. sulphate of potash and 400 lb. mixed mineral manure	5	8	1	1
5	3-1/2 cwt. superphosphate	5	0	1	1
6	3-1/2 cwt. superphosphate, and 500 lb. sulphate of potash	4	9	0	18
7	3-1/2 cwt. superphosphate, 500 lb. sulphate of potash, and 36-1/2 lb. ammonium salts	5	17	1	8

TABLE IX.—continued

		Series 2.				Series 3.
	STANDARD MANURES	Standard manures,				Standard manures,
		and cross-dressed with—				and cross-dressed with—
		550 lb. nitrate of soda.				400 lb. amonium salts.
Plots.
		Roots.		Leaves.		Roots.		Leaves.
		Tons.	cwt.	Tons.	cwt.	Tons.	cwt.	Tons.	cwt.
1	Farmyard manure, 14 tons	22	11	4	2	22	3	5	7
2	Farmyard manure, 14 tons, and 3-1/2 cwt. superphosphate	23	12	4	14	21	8	5	6
3	Without manure, 1846, and since	13	7	3	4	6	14	2	18
4	3-1/2 cwt. superphosphate, 500 lb. sulphate of potash, and 400 lb. mixed mineral manure	12	17	3	15	16	2	3	0
5	3-1/2 cwt. superphosphate	15	13	3	5	8	10	3	1
6	3-1/2 cwt. superphosphate, and 500 lb. sulphate of potash	15	15	2	18	14	6	2	16
7	3-1/2 cwt. superphosphate, 500 lb. sulphate of potash, and 36-1/2 lb. ammonium salts	16	0	3	1	16	3	3	0

TABLE IX.—continued

		Series 4.				Series 5.
	STANDARD MANURES	Standard manures,				Standard manures,
		and cross-dressed with				and cross-dressed with
		2000 lb. rape-cake, and				2000 lb. rape-cake.
Plots.		400 lb. ammonium salts.
		Roots.		Leaves.		Roots.		Leaves.
		Tons.	cwt.	Tons.	cwt.	Tons.	cwt.	Tons.	cwt.
1	Farmyard manure, 14 tons	24	11	6	1	23	7	4	6
2	Farmyard manure, 14 tons, and 3-1/2 cwt. superphosphate	23	12	6	1	23	1	4	6
3	Without manure, 1846, and since	10	11	3	17	11	2	3	0
4	3-1/2 cwt. superphosphate, 500 lb. sulphate of potash, and 400 lb. mixed mineral manure	24	18	5	7	20	4	3	9
5	3-1/2 cwt. superphosphate	11	7	4	2	12	3	3	2
6	3-1/2 cwt. superphosphate, and 500 lb. sulphate of potash	21	6	5	7	16	14	2	15
7	3-1/2 cwt. superphosphate, 500 lb. sulphate of potash, and 36-1/2 lb. ammonium salts	21	6	5	9	17	10	3	3

TABLE X.—Experiments with different Manures on Permanent Meadow-land.

Thirty-six Years, 1856-91.

	Produce per Acre, weighed as Hay.
	Average per annum,			Average per annum,
Manures per Acre per Annum.	20 years, 1856-75			16 years, 1876-91
	(1st crops only).			(1st and 2d crops).
	10 years,	10 years,	20 years,	1st	2nd
	1856-65.	1866-75.	1856-75.	crops.	crops.	Total.
	cwt.	cwt.	cwt.	cwt.	cwt.	cwt.
Unmanured continuously	22-1/2	20	21-1/4	18	8-1/2	26-1/2
3-12 cwt. superphosphate of lime	23-14	21-1/4	22-1/4	18	9	27-1/2
3-1/2 cwt. superphosphate of lime, and 400 lb. ammonium salts	33-7/8	30-1/2	32-1/4	30-3/4	10-1/2	41-1/4
400 lb. ammonium salts	30-1/2	22	26-1/4	18-1/4	10-1/8	27-3/8
275 lb. nitrate of soda, 3-1/2 cwt. superphosphate, and mixed mineral manure	45-1/4	47-5/8	46-1/2	41-1/8	12-1/8	53-1/4
275 lb. nitrate of soda	34-1/4	33-1/2	33-7/8	30-1/8	10	40-1/8

TABLE XI.—Experiments on the Growth of Potatoes.

Average of Five Seasons, 1876-80.¹

		Produce per Acre—Tubers.
Plot.	Manures per Acre per Annum	Good.		Small.		Diseased.		Total.
		Tons.	cwt.	Tons.	cwt.	Tons.	cwt.	Tons.	cwt.
1	Unmanured	1	18	0	6-1/4	0	2-1/4	2	7-1/2
2	Farmyard manure (14 tons)	3	19-3/8	0	7-5/8	0	6-5/8	4	13-5/8
3	Farmyard manure (14 tons), and 3-1/2 cwt. superphosphate	4	9-1/2	0	8	0	8-3/4	5	6-1/4
4	Farmyard manure (14 tons), 3-1/2 cwt. superphosphate, and 550 lb. nitrate of soda	5	8	0	7	0	19-1/2	6	14-1/2
5	400 lb. ammonium salts	1	19-1/2	0	7-1/8	0	3-1/2	2	10-1/8
6	550 lb. nitrate of soda	2	11-7/8	0	6-7/8	0	5-1/4	3	4
7	400 lb. ammonium salts, 3-1/2 cwt. superphosphate, 300 lb. sulphate potash, 100 lb. sulphate soda, 100 lb. sulphate magnesia	5	14-1/4	0	8-1/4	0	14-3/4	6	17-1/4
8	550 lb. nitrate of soda, 33-1/2 cwt. superphosphate, 300 lb. sulphate potash, 100 lb. sulphate soda, 100 lb. sulphate magnesia	5	19-7/8	0	7-7/8	0	19-1/8	7	6-7/8
9	3-1/2 cwt. superphosphate	3	0-3/4	0	8	0	4-5/8	3	13-3/8
10	3-1/2 cwt. superphosphate, 300 lb. sulphate potash, 100 lb. sulphate soda, and 100 lb. sulphate magnesia	3	4-1/2	0	6-1/2	0	4-7/8	3	15-7/8
1. In each year the tops were spread on the respective plots.

TABLE XII.—Experiments on the Growth of Potatoes—Continued.

Average of Twelve Seasons, 1881-92.

		Produce per Acre—Tubers.
Plot.	Manures per Acre per Annum	Good.		Small.		Diseased.		Total.
		Tons.	cwt.	Tons.	cwt.	Tons.	cwt.	Tons.	cwt.
1	Unmanured in 1876, and each year since	1	3-3/4	0	3-3/4	0	0-1/4	1	7-3/4
2	Unmanured in 1882, and since; previously farmyard manure (14 tons)	2	14-1/4	0	4-3/4	0	2	3	1
3	Farmyard manure (14 tons) alone, 1883, and since; previously 3-1/2 cwt. superphosphate also	4	3-1/4	0	4-1/4	0	4-1/2	4	12
4	Farmyard manure (14 tons) alone, 1883, and since. In 1882 and previously 3-1/2 cwt. superphosphate, and in 1881 and previously 550 lb. nitrate of soda also	4	6-1/4	0	4-1/2	0	4-3/4	4	15-1/2
5	400 lb. ammonium salts	1	2-3/4	0	4-3/4	0	0-1/2	1	8
6	550 lb. nitrate of soda	1	17-3/4	0	3-3/4	0	0-3/4	2	2-1/4
7	400 lb. ammonium salts, 3-1/2 cwt. superphosphate, 300 lb. sulphate of potash, and 200 lb. mixed mineral manure	5	6-3/4	0	5	0	4-1/2	5	16-1/4
8	550 lb. nitrate of soda, 3-1/2 cwt. superphosphate, 300 lb. sulphate of potash, and 200 lb. mixed mineral manure	5	7-1/2	0	4-1/4	0	3-3/4	5	15-1/2
9	3-1/2 cwt. superphosphate	2	17-3/4	0	3-1/4	0	1	3	2
10	3-1/2 cwt. superphosphate, 300 lb. sulphate of potash, and 200 lb. mixed mineral manure	3	2-1/4	0	3-1/4	0	1-1/4	3	6-3/4

Footnotes

256 See Sir John Bennet Lawes, Bart., and the Rothamsted Experiments. By C. M. Aikman. (‘Scottish Farmer’ Office, Glasgow.)

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