Manures and the Principles of Manuring

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 129 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 III. Nitrogen 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 pasture 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-- 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-- 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 248 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 applied 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

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