It is also his pleasing duty to thank his friends Dr Bernard Dyer, Hon Secretary of the Society of Public Analysts, Dr A. P. Aitken, Chemist to the Highland and Agricultural Society of Scotland; Professor Douglas Gilchrist of Bangor; Mr F. J. Cooke, late of Flitcham; Mr Hermann Voss of London; and Professor Wright of Glasgow, for having assisted him in the revision of proof-sheets.

Analytical Laboratory,
128 Wellington Street, Glasgow,
January 1894.

CONTENTS.

PART I.—HISTORICAL INTRODUCTION.
PAGE
Beginning of agricultural chemistry[4]
Early theories regarding plant-growth[4]
Van Helmont[4]
Digby[6]
Duhamel and Stephen Hales[8]
Jethro Tull[9]
Charles Bonnet's discovery of source of plants' carbon[11]
Researches of Priestley, Ingenhousz, Sénébier, on assimilation of carbon[11-12]
Publication of first English treatise by Earl Dundonald[13]
Publication of Theodore de Saussure, 'Chemical Researches on Vegetation,' 1804[14]
Theories on source of plant-nitrogen[15]
Early experiments on this subject[16]
Sir Humphry Davy's lectures (1802-1812)[17]
State of agricultural chemistry in 1812[17]
Beginning of Boussingault's researches (1834)[21]
Publication of Liebig's first report to the British Association[24]
Refutation of "humus" theory[26]
Liebig's mineral theory[26]
Liebig's theory of source of plants' nitrogen[27]
Publication of Liebig's second report to British Association[30]
Liebig's services to agricultural chemistry[31]
Development of agricultural research in Germany[32]
The Rothamsted Experiment Station[33]
Sir J. B. Lawes and Sir J. H. Gilbert, the nature and value of their experiments[33]
Review of the present state of our knowledge of plant-growth[36]
Proximate composition of the plant[36]
Fixation of carbon by plants[37]
Action of light on plant-growth, Dr Siemens' experiments[38]
Source of oxygen and hydrogen in the plant[39-40]
Source of nitrogen in the plant[40]
Relation of the free nitrogen to leguminous plants[42-44]
Relation of nitrogen in organic forms, as ammonia salts, and nitrates to the plant[46-50]
Nitrification and its conditions[51]
Ash constituents of the plant[53]
Methods of research for ascertaining essentialness of ash constituents of plants[53]
(a) Artificial soils, (b) water-culture[53-55]
Method in which plants absorb their food-constituents[55]
Endosmosis[55]
Retention by soils of plant-food[57]
Causes of retention by soils of plant-food[59]
Manuring[60]
"Field" and "pot" experimentation[60]
PART II.—PRINCIPLES OF MANURING.
CHAPTER I.—FERTILITY OF THE SOIL.
What constitutes fertility in a soil[65]
I.Physical properties of a soil[65]
Kinds of soils[66]
Absorptive power for water of soils[67]
Absorptive power for water of sand, clay, and humus[68]
Fineness of particles of a soil[69]
Limit of fineness of soil-particles[69]
Importance of retentive power[70]
Power of plants for absorbing water from a soil, experiments by Sachs[73]
How to increase absorptive power of soils[74]
Amount of water in a soil most favourable for plant growth[75]
Hygroscopic power of soils[75]
Capacity of soils for absorbing and retaining heat[76]
Explanation of dew[77]
Heat of soils[78]
Heat in rotting farmyard manure[78]
Causes of heat of fermentation[79]
Influence of colour on heat-retaining power[80]
Power of soils for absorbing gases[81]
Gases found in soils[81]
Variation in gas-absorbing power of soils[82]
Absorption of nitrogen by soils[82]
Requirements of plant-roots in a soil[83]
Influence of tillage on number of plants in a certain area[86]
Comparison of English and American farming[86]
II.Chemical composition of a soil[87]
Fertilising ingredients of a soil[87]
Importance of nitrogen, phosphoric acid, and potash in a soil[88]
Chemical condition of fertilising ingredients in soils[89]
Amount of soluble fertilising ingredients in soils[90]
Value of chemical analysis of soils[90]
III.Biological properties of a soil[92]
Bacteria of the soil[92]
Recapitulation of Chapter I[96]
APPENDIX TO CHAPTER I.
NOTE
I.Table of absorptive power of soil substances by Schübler[98]
II.Table of rate of evaporation of water in different soils by Schübler[99]
III.Table of hygroscopic power of soils dried at 212° F. (Davy)[99]
IV.Gases persent in soil[100]
V.Amount of plant-food in soils[100]
VI.Chemical composition of the soil[101]
VII.Forms in which plant-foods are present in the soil[107]
CHAPTER II.—FUNCTIONS PERFORMED BY MANURES.
Etymological meaning of word manure[109]
Definition of manures[110]
Different classes of manures[111]
Action of different classes of manures[113]
CHAPTER III.—POSITION OF NITROGEN IN AGRICULTURE.
The Rothamsted experiments and the nitrogen question[115]
Different forms in which nitrogen exists in nature[116]
Relation of "free" nitrogen to the plant[117]
Combined nitrogen in the air[118]
Amount of combined nitrogen falling in the rain[119]
Nitrogen in the soil[120]
Nitrogen in the subsoil[121]
Nitrogen of surface-soil[121]
Amount of nitrogen in the soil[123]
Soils richest in nitrogen[123]
Nature of the nitrogen in the soil[124]
Organic nitrogen in the soil[125]
Differences of surface and subsoil nitrogen[126]
Nitrogen as ammonia in soils[127]
Amount of ammonia in soils[127]
Nitrogen present as nitrates in the soil[128]
Position of nitric nitrogen in soil[128]
Amount of nitrates in the soil[120]
Amount of nitrates in fallow soils[129]
Amount of nitrates in cropped soils[130]
Amount of nitrates in manured wheat-soils[131]
The sources of soil-nitrogen[131]
Accumulation of soil-nitrogen under natural conditions[133]
Accumulation of nitrogen in pastures[134]
Gain of nitrogen with leguminous crops[135]
The fixation of "free" nitrogen[136]
Influence of manures in increasing soil-nitrogen[136]
Sources of loss of nitrogen[137]
Loss of nitrates by drainage[137]
Prevention of loss of nitrogen by permanent pasture and
"catch-cropping"		[138]
Other conditions diminishing loss of nitrates[139]
Amount of loss of nitrogen by drainage[140]
Loss of nitrogen in form of "free" nitrogen[141]
Total amount of loss of nitrogen[142]
Loss of nitrogen by retrogression[142]
Artificial sources of loss of nitrogen[144]
Amount of nitrogen removed in crops[144]
Losses of nitrogen incurred on the farm[146]
Loss in treatment of farmyard manure[146]
Nitrogen removed in milk[147]
Economics of the nitrogen question[147]
Loss of nitrogen-compounds in the arts[148]
Loss due to use of gunpowder[148]
Loss due to sewage disposal[149]
Our artificial nitrogen supply [150]
Nitrate of soda and sulphate of ammonia[150]
Peruvian guano[151]
Bones[151]
Other nitrogenous manures[152]
Oil-seeds and oilcakes[153]
Other imported sources of nitrogen[153]
Conclusion[153]
APPENDIX TO CHAPTER III.
NOTE
I.Determination of the quantity of nitrogen supplied by rain, as ammonia and nitric acid, to an acre of land during one year[155]
II.Nitrogen in soils at various depths[156]
IIINitrogen as nitrates in cropped soils receiving no nitrogenous manures, in lb. per acre (Rothamsted soils)[157]
IV.Nitrogen as nitrates in Rothamsted soils[157]
V.Examples of increase of nitrogen in Rothamsted soils laid down in pastures[158]
VI.Loss by drainage of nitrates[158]
VII.Examples of decrease of nitrogen in Rothamsted soils[159]
VIII.Amount of drainage and nitrogen as nitrates in drainage-water from unmanured bare soil, 20 and 60 inches deep[160]
CHAPTER IV.—NITRIFICATION.
Process of nitrification[161]
Occurrence of nitrates in the soil[162]
Nitre soils of India[162]
Saltpetre plantations[163]
Cause of nitrification[165]
Ferments effecting nitrification[167]
Appearance of nitrous organisms[168]
Nitric organism[169]
Difficulty in isolating them[169]
Nitrifying organisms do not require organic matter[169]
Conditions favourable for nitrification—
Presence of food-constituents[170]
Presence of a salifiable base[171]
Only takes place in slightly alkaline solutions[172]
Action of gypsum on nitrification[173]
Presence of oxygen[173]
Temperature[175]
Presence of a sufficient quantity of moisture[176]
Absence of strong sunlight[176]
Nitrifying organisms destroyed by poisons[176]
Denitrification[177]
Denitrification also effected by bacteria[178]
Conditions favourable for denitrification[178]
Takes place in water-logged soils[179]
Distribution of the nitrifying organisms in the soil[179]
Depth down at which they occur[180]
Action of plant-roots in promoting nitrification[181]
Nature of substances capable of nitrification[181]
Rate at which nitrification takes place[183]
Nitrification takes place chiefly during summer[183]
Process goes on most quickly in fallow fields[184]
Laboratory experiments on rate of nitrification[185]
Certain portions of soil-nitrogen more easily nitrifiable than the rest[187]
Rate of nitrification deduced from field experiments[187]
Quantity of nitrates formed in the soils of fallow fields[188]
Position of nitrates depends on season[188]
Nitrates in drainage-waters[188]
Amount produced at different times of year[189]
Nitrification of manures[190]
Ammonia salts most easily nitrifiable[191]
Sulphate of ammonia the most easily nitrifiable manure[191]
Rate of nitrification of other manures[192]
Soils best suited for nitrification[192]
Absence of nitrification in forest-soils[193]
Important bearing of nitrification on agricultural practice[193]
Desirable to have soil covered with vegetation[194]
Permanent pasture most economical condition of soil[194]
Nitrification and rotation of crops[195]
APPENDIX TO CHAPTER IV.
NOTE
I.Old theories of nitrification[196]
II.Nitrification takes place in solutions devoid of organic matter[196]
III.Oxidising power of micro-organisms in soils[197]
IV.Effect of urine on nitrification in soils[197]
V.Solution used by Professor Frankland in cultivating nitrificative micro-organisms[198]
VI.Experiments by Boussingault on rate of nitrification[198]
VII.Nitrogen as nitrates in Rothamsted soils after bare fallow in lb. per acre[198]
CHAPTER V.—POSITION OF PHOSPHORIC ACID
IN AGRICULTURE.
Occurrence of phosphoric acid in nature[199]
Mineral sources of phosphoric acid[200]
Apatite and phosphorite[200]
Coprolites[201]
Occurrence of phosphoric acid in guanos[202]
Universal occurrence in common rocks[202]
Occurrence in the soil[203]
Condition in which phosphoric acid occurs in the soil[203]
Occurrence in plants[204]
Occurrence in animals[205]
Sources of loss of phosphoric acid in agriculture[205]
Loss of phosphoric acid by drainage[206]
Artificial sources of loss of phosphoric acid[206]
Amount of phosphoric acid removed in milk[207]
Loss of phosphoric acid in treatment of farmyard manure[208]
Loss of phosphoric acid in sewage[208]
Sources of artificial gain of phosphoric acid[208]
APPENDIX TO CHAPTER V.
NOTE
I.Composition of apatite (Voelcker)[210]
II.Percentage of phosphoric acid in the commoner rocks[211]
CHAPTER VI.—POSITION OF POTASH IN AGRICULTURE.
Potash of less importance than phosphoric acid[212]
Occurrence of potash[213]
Felspar and other potash minerals[213]
Stassfurt salts[214]
Occurrence of saltpetre[215]
Occurrence of potash in the soil[215]
Potash chiefly in insoluble condition in soils[216]
Percentage of potash in plants and plant-ash[216]
Occurrence of potash in animal tissue[217]
Sources of loss of potash[217]
Amount of potash removed in crops[218]
Amount of potash removed in milk[218]
Potash manures[218]
APPENDIX TO CHAPTER VI.
NOTE
I.Amount of potash in different minerals[220]
II.Quantity of potash obtained from 1000 lb. of different kinds of vegetation in the manufacture of potashes[220]
PART III.—MANURES.
CHAPTER VII.—FARMYARD MANURE.
Variation in its composition[223]
Made up of three classes of constituents[224]
Solid excreta—
Its nature[224]
Difference in composition of the solid excreta of the different farm animals[224]
Causes of this difference[225]
Percentage of manurial ingredients in solid excreta of different animals[226]
Urine—[228]
Its nature[228]
Variation in its composition[229]
Causes of this variation[229]
Manurial value of the urine of the different farm animals[230]
Percentage of the organic matter, nitrogen, and mineral substances in the food, voided in the solid excreta and urine[232]
Comparison of manurial value of total excrements of the different farm animals[234]
Nature of changes undergone by food in process of digestion[235]
Litter—[236]
Its uses[236]
Straw as litter, and its qualifications[237]
Composition of different kinds of straw[238]
Loam as litter[239]
Peat as litter[240]
Comparison of properties of peat-moss and straw[241]
The bracken-fern as litter[241]
Dried leaves as litter[242]
Manures produced by the different animals—
Horse-manure—
Amount produced[243]
Its nature and composition[243]
Amount of straw used for litter[244]
Sources of loss on keeping[245]
How to prevent loss[245]
Use of "fixers," and the nature of their action[245]
Cow-manure—
Amount produced[248]
Its nature and composition[249]
Amount of straw used as litter[248]
Sources of loss on keeping[249]
Advantages of short dung[249]
Pig-manure—
Amount produced[250]
Its nature and composition[250]
Amount of straw used as litter[251]
Sheep-manure—
Amount produced[251]
Nature and composition[251]
Amount of straw used as litter[252]
Methods of calculating amount of manure produced on the farm[252, note]
Fermentation of farmyard manure—
Action of micro-organic life in producing fermentation[255]
Two classes of bacteria active in this work, aerobies and anaerobies[255]
Conditions influencing fermentation—
Temperature[256]
Openness to the air[256]
Dampness[257]
Composition of manure[257]
Products of fermentation[257]
Analyses of farmyard manure—
Dr Voelcker's experiments[259]
Variation in composition[259]
Amounts of moisture, organic matter (containing nitrogen), and mineral matter[260]
Its manurial value compared with nitrate of soda, sulphate of ammonia, and superphosphate[260]
Comparison of fresh and rotten manure—
The nature and amount of loss sustained in the process of rotting[261]
Ought manure to be appliled fresh or rotten?[262]
Relative merits of covered and uncovered manure-heaps[263]
Methods of application of farmyard manure to the field—
Merits and demerits of the different methods[265]
Setting it out in heaps[265]
Spreading it broadcast, and letting it lie[266]
Ploughing it in immediately[267]
Value and function of farmyard manure—
As a supplier of the necessary elements of plant-food[268]
As a "universal" manure[269]
Proportion in which nitrogen, phosphoric acid, and potash are required by crops[269]
Proportion in which they are present in farmyard manure[270]
Farmyard manure poor in nitrogen[270]
Lawes' and Gilbert's experiments[271]
How it may be best reinforced by the use of "artificials"[271]
Indirect value of farmyard manure as a supplier of humus to the soil[273]
Its influence on soil-texture[273]
Its influence in setting free inert fertilising matter in the soil[274]
Rate at which farmyard manure ought to be applied[275]
Lasting nature of farmyard manure[276]
Its economic value[276]
APPENDIX TO CHAPTER VII.
NOTE
I.Difference in amount of excreta voided for food consumed[279]
II.Solid excreta voided by sheep, oxen, and cows[279]
III.Urine voided by sheep, oxen, and cows[280]
IV.Percentage of food voided in the solid and liquid excrements[281]
V.Pig excrements[281]
VI.Manurial constituents in 1000 parts of ordinary foods[282]
VII.Analyses of stable-manure, made respectively with peat-moss litter and wheat-straw[283]
VIII.Analyses of bracken[283]
IX.Analyses of horse-manure[283]
X.The nature of the chemical reactions of ammonia "fixers"[284]
XI.Analyses of cow-manure[286]
XII.Composition of fresh and rotten farmyard manure[286]
XIII.Comparison of fresh and rotten manure[288]
XIV.Lord Kinnaird's experiments[289]
XV.Drainings of manure-heaps[290]
XVI.Amounts of potash and phosphoric acid removed by rotation from a Prussian morgen (.631 acre)[290]
XVII.Composition of farmyard manure (fresh)[291]
XVIII.The urine (quantity voided)[291]
CHAPTER VIII.—GUANO.
Importance in agriculture[293]
Influence on British farming[294]
Influence of guano not wholly good[295]
Value of guano as a manure[296]
Origin and occurrence of guano[297]
Variation in composition of different guanos[299]
I.Nitrogenous guano—
(a)Peruvian guano[300]
Different deposits of Peruvian guano[301]
Appearance, colour, and nature of Peruvian guano[303]
Composition of Peruvian guano[304]
(b)Other nitrogenous manures: Angamos, Ichaboe[306]
II.Phosphatic guanos—
Occurrence of phosphatic guanos[308]
Inequality in composition of phosphatic guanos[309]
"Dissolved" phosphatic guano[310]
"Equalised" or "rectified" guano[311]
The action of phosphatic guanos as manures[312]
Proportion of fertilising constituents in guano[314]
Mode of application of guanos[315]
Quantity of guano to be used[317]
Adulteration of guano[318]
So-called guanos—
Fish-guano[320]
Value of fish-guano[322]
Mean-meal guano[324]
Value of meat-meal guano[324]
Bat guano[325]
Pigeon and fowl dung[325]
APPENDIX TO CHAPTER VIII.
NOTE
I.Peruvian guano imported into United Kingdom, 1865-1893[327]
II.Guano deposits of the world[327]
III.Composition of concretionary nodules[328]
IV.Table showing gradual deterioration of Peruvian guano, 1867-1881[329]
V.Composition of different guanos[329]
VI.Liebig's theory as to the action of oxalic acid in guano[330]
VII.Analyses of dung of fowls, pigeons, ducks, and geese[331]
CHAPTER IX.—NITRATE OF SODA.
Amount of exports[332]
Date of discovery of nitrate deposits[333]
The origin of nitrate deposits[334]
Forbes and Darwin on the theory of their origin[335]
Source of nitric acid in nitrate of soda[337]
Guano theory of origin of nitrate of soda[337]
Nitric acid in nitrate of soda probably derived from sea-weed[339]
Appearance of nitrate-fields[340]
The method of mining the nitrate of soda[341]
Composition of caliche[342]
Extent of the nitrate deposits[342]
Composition and properties of nitrate of soda[343]
Nitrate applied as a top-dressing[344]
Nitrate of soda encourages deep roots[344]
Is nitrate of soda an exhausting manure?[345]
Crops for which nitrate of soda is suited[346]
Method of application of nitrate of soda[347]
Importance of having a sufficiency of other fertilising constituents[348]
Conclusions drawn[349]
APPENDIX TO CHAPTER IX.
Total shipmentes from South America, 1830-1893[351]
Total imports into Europe and United Kingdom, 1873-1892[351]
CHAPTER X.—SULPHATE OF AMMONIA.
Value of ammonia as a manure[352]
Sources of sulphate of ammonia[353]
Ammonia from gas-works[353]
Other sources[354]
Composition, &c., of sulphate of ammonia[355]
Application of sulphate of ammonia[356]
APPENDIX TO CHAPTER X.
Production of sulphate of ammonia in United Kingdom, 1870-1892[358]
CHAPTER XI.—BONES.
Early use of bones[359]
Different forms in which bones are used[360]
Composition of bones[362]
The organic matter of bones[363]
The inorganic matter of bones[363]
Treatment of bones[364]
Action of bones[365]
Dissolved bones[368]
Crops suited for bones[368]
Bone-ash[369]
Bone-char or bone-black[369]
APPENDIX TO CHAPTER XI.
NOTE
I.Analysis of bone-meal[371]
II.Analysis of dissolved bones[371]
III.Composition of bone-ash[372]
IV.Composition of bone-char[372]
CHAPTER XII.—MINERAL PHOSPHATES.
Coprolites[373]
Canadian apatite or phosphorite[374]
Estremadura or Spanish phosphates[375]
Norwegian apatite[376]
Charlestown or South Carolina phosphate[376]
Belgian phosphate[377]
Somme phosphate[378]
Florida phosphate[378]
Lahn phosphate[379]
Bordeaux or French phosphate[379]
Algerian phosphate[379]
Crust guanos[379]
Value of mineral phosphates as manures[380]
APPENDIX TO CHAPTER XII.
Imports of phosphates[381]
CHAPTER XIII.—SUPERPHOSPHATES.
Discovery of superphosphate by Liebig[382]
Manufacture of superphosphate[383]
Nature of the reaction taking place[385]
Phosphates of lime[385]
Reverted phosphate[389]
Value of reverted phosphate[391]
Composition of superphosphates[391]
Action of superphosphates[392]
Action of superphosphate sometimes unfavourable[395]
Application of superphosphate[395]
Value of insoluble phosphates[396]
Rate at which superphosphate is applied[397]
APPENDIX TO CHAPTER XIII.
NOTE
I.The formulæ, and molecular and percentage composition, of the different phosphates[398]
II.Reactions of sulphuric acid and phosphate of lime[398]
III.Table for conversion of soluble phosphate into insoluble phosphate[399]
IV.Action of iron and alumina in causing reversion[399]
V.Relative trade values of phosphoric acid in different manures[400]
CHAPTER XIV.—PHOSPHATE OR BASIC SLAG.
Its manufacture[401]
Not at first used[403]
Discovery of its value as a manure[403]
Composition of basic slag[404]
Processes for preparing slag[406]
Solubility of basic slag[408]
Darmstadt experiments with basic slag[410]
Results of other experiments[413]
Soils most suited for slag[414]
Rate of application[414]
Method of application[416]
APPENDIX TO CHAPTER XIV.
Analysis of basic slag[417]
CHAPTER XV.—POTASSIC MANURES.
Relative importance[418]
Scottish soils supplied with potash[419]
Sources of potassic manures[419]
Stassfurt potash salts[420]
Relative merits of sulphate and muriate of potash[421]
Application of potash manures[422]
Soils and crops suited for potash manures[423]
Rate of application[423]
CHAPTER XVI.—MINOR ARTIFICIAL MANURES.
Scutch[427]
Shoddy and wool-waste[427]
Soot[428]
CHAPTER XVII.—SEWAGE AS A MANURE.
Irrigation[431]
Effects of continued application of sewage[433]
Intermittent irrigation[434]
Crops suited for sewage[434]
Treatment of sewage by precipitation, &c.[436]
Value of sewage sludge[439]
CHAPTER XVIII.—LIQUID MANURE[442]
CHAPTER XIX.—COMPOSTS.
Farmyard manure a typical compost[446]
Other composts[447]
CHAPTER XX.—INDIRECT MANURES.
Lime[449]
Antiquity of lime as a manure[449]
Action of lime[449]
Lime a necessary plant-food[450]
Lime of abundant occurrence[452]
Lime returned to the soil in ordinary agricultural practice[452]
Different forms of lime[453]
Caustic lime[453]
Lime acts both mechanically and chemically[455]
I.Mechanical functions of lime[455]
Action on soil's texture[455]
Lime renders light soils more cohesive[457]
II.Chemical action of lime[457]
III.Biological action of lime[459]
Action of lime on nitrogenous organic matter[460]
Recapitulation[461]
CHAPTER XXI.—INDIRECT MANURES—GYPSUM, SALT, Etc.
Gypsum[462]
Mode in which gypsum acts[462]
Salt[465]
Antiquity of the use of salt[465]
Nature of its action[465]
Salt not a necessary plant-food[466]
Can soda replace potash?[466]
Salt of universal occurrence[467]
Special sources of salt[468]
The action of salt[468]
Mechanical action on soils[470]
Solvent action[470]
Best used in small quantities along with manures[472]
Affects quality of crop[472]
Rate of application[473]
CHAPTER XXII.—THE APPLICATION OF MANURES.
Influence of manures in increasing soil-fertility[474]
Influence of farmyard manure on the soil[475]
Farmyard manure v. artificials[476]
Farmyard manure not favourable to certain crops[477]
Conditions determining the application of artificial manures[477]
Nature of the manure[478]
Nitrogenous manures[478]
Phosphatic manures[480]
Potash manures[480]
Nature of soil[481]
Nature of previous manuring[482]
Nature of the crop[483]
Amounts of fertilising ingredients removed from the soil by different crops[484]
Capacity of crops for assimilating manures[486]
Difference in root-systems of different crops[488]
Period of growth[489]
Variation in composition of crops[490]
Absorption of plant-food[490]
Fertilising ingredients lodge in the seed[491]
Forms in which nitrogen exists in plants[491]
Bearing of above on agricultural practice[492]
Influence of excessive manuring of crops[492]
CHAPTER XXIII.—MANURING OF THE COMMON FARM CROPS.
Cereals[493]
Especially benefited by nitrogenous manures[494]
Power of absorbing silicates[494]
Barley[495]
Period of growth[495]
Most suitable soil[496]
Farmyard manure not suitable[497]
Importance of uniform manuring of barley[497]
Norfolk experiments on barley[497]
Proportion of grain to straw[498]
Wheat[499]
Rothamsted experiments[500]
Continuous growth[500]
Flitcham experiments[500]
Oats[501]
A very hardy crop[502]
Require mixed nitrogenous manuring[502]
Arendt's experiments[503]
Avenine[503]
Quantities of manures[504]
Grass[504]
Effect of manures on herbage of pastures[505]
Influence of farmyard manure[506]
Influence of soil and season on pastures[507]
Manuring of meadow land[508]
Bangor experiments[508]
Norfolk experiments[509]
Manuring of permanent pastures[509]
Roots[510]
Influence of manure on composition[512]
Nitrogenous manures increase sugar[512]
Amount of nitrogen recovered in increase of crop[513]
Norfolk experiments[513]
Manure for swedes[514]
Highland Society's experiments[515]
Manuring for rich crops of turnips[516]
Experiments by the author on turnips[516]
Potatoes[517]
Highland Society's experiments[518]
The Rothamsted experiments[519]
Effect of farmyard manure[520]
Manuring of potatoes in Jersey[521]
The influence of manure on the composition[521]
Leguminous crops[522]
Leguminous plants benefit by potash[523]
Nitrogenous manures may be hurtful[523]
Clover sickness[524]
Alternate wheat and bean rotation[524]
Beans[525]
Manure for beans[525]
Relative value of manurial ingredients[526]
Gypsum as a bean manure[526]
Effect of manure on composition of crop[527]
Peas[527]
Hops[528]
Cabbages[528]
APPENDIX TO CHAPTER XXIII.
Experiments on bean-manuring[530]
CHAPTER XXIV.—ON THE METHOD OF APPLICATION,
AND ON THE MIXING OF MANURES
Equal distribution of manures[531]
Mixing manures[532]
Risks of loss in mixtures[533]
Loss of ammonia[533]
Effects of lime on ammonia[535]
Loss of nitric acid[536]
Reversion of phosphates[537]
Manurial ingredients should be applied separately[538]
CHAPTER XXV.—ON THE VALUATION AND ANALYSIS OF MANURES.
Value of chemical analysis[539]
Interpretation of chemical analysis[539]
Nitrogen[540]
Phosphoric acid[541]
Importance of mechanical condition of phosphate[542]
Potash[542]
Other items in the chemical analysis of manures[543]
Fertilisers and Feeding Stuffs Act[543]
Different methods of valuing manures[544]
Unit value of manurial ingredients[544]
Intrinsic value of manures[545]
Field experiments[545]
Educational value of field experiments[547]
Value of manures deduced from experiments[548]
Value of unexhausted manures[549]
Potential fertility of a soil[549]
Tables of value of unexhausted manures[551]
APPENDIX TO CHAPTER XXV.
NOTE
I.Factors for calculating compounds from manurial ingredients[553]
II.Units for determining commercial value of manures and cash prices of manures[554, 555]
III.Manurial value of nitrogen and potash in different substances[556]
IV.Comparative manurial value of different forms of nitrogen and potash[557]
V.Lawes' and Gilbert's tables for calculating unexhausted value of manures[559]
CHAPTER XXVI.—THE ROTHAMSTED EXPERIMENTS.
Nature of experiments on crops and manures[561]
Soil of Rothamsted[561]
Table I. List of Rothamsted field experiments[562]
Wheat experiments—
Unmanured plots[565]
Wheat grown continuously on same land (unmanured)[562]
Table II. Results of first eight years[562]
Table III. Results of subsequent forty years[562]
Tablel IV. Wheat grown continuously with farmyard manure (14 tons per annum)[564]
Table V. Wheat grown continuously with artificial manures[565]
Table VI. Experiments on the growth of barley, forty years, 1852-91[566]
Table VIII. Experiments on the growth of oats, 1869-78[567]
Table IX. Experiments on mangel-wurzel[568, 569]
Table X. Experiments with different manures on permanent meadow-land, thirty-six years, 1856-91[570]
Table XI. Experiments on the growth of potatoes— average for five seasons, 1876-80[571]
Table XII. Experiments on growth of potatoes (continued)—average for twelve seasons, 1881-92[572]
_______________
Index[573]

PART I.

HISTORICAL INTRODUCTION