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Manures and the principles of manuring. Charles Morton Aikman
href="#ulink_116ea0dd-a369-5e04-ac23-b5834a962796">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