Chapter 2

SOIL FERTILITY AS AFFECTED BY FARM OPERATIONS AND FARM PRACTICES

Chapter Page

XVI.--A FERTILE SOIL 141 Physical properties: Power to absorb and hold water Power of ventilation Power to absorb and hold heat 142 Biological properties 143 Nitrogen-fixing germs 144 Nitrifying germs 145 Denitrifying germs 147 Chemical properties: Nitrogen in the soil Phosphoric acid in the soil Potash in the soil Lime in the soil Great importance of physical properties 147 Maintenance of fertility 150

XVII.--SOIL WATER 151 Importance of soil water 151 Necessity of soil water 151 Sources and forms of soil water 153 Too much water 154 Not enough water 154 Loss of soil water 155 How some farm operations influence soil water 156 Hoeing, raking, harrowing and cultivating 158 Manures and soil water 159 Methods of cropping and soil water 159 Selection of crops with reference to soil water 160

XVIII.--THE AFTER-CULTIVATION OF CROPS 164 Loss of water by evaporation 164 Loss of water through weeds 165 Saving the water 165 Time to cultivate 166 Tools for after-cultivation 167 Hilling and ridging 169

XIX.--FARM MANURES 171 The functions of manures and fertilizers 171 Classification 171 Importance of farm manures 172 Barn or stable manure 173 Loss of value 173 Checking the losses 176 Applying the manure to the soil 177 Proper condition of manure when applied 179 Composts 181

XX.--FARM MANURES, CONCLUDED 183 Green-crop manures: Functions 183 Benefits 185 Character of best plants for green-crop manuring 185 The time for green-manure crops 186 Leguminous green-manure crops 186 Non-leguminous green-manure plants 191

XXI.--COMMERCIAL FERTILIZERS 192 The raw materials 192 Sources of nitrogen 193 Sources of phosphoric acid 195 Sources of potash 199 Sources of lime 200

XXII.--COMMERCIAL FERTILIZERS, CONTINUED 202 Mixed fertilizers: What they are Many brands Safeguard for the farmer Low grade materials Inflating the guarantee 202 Valuation 205 Low grade mixtures 207 Buy on the plant food basis 209

XXIII.--COMMERCIAL FERTILIZERS, CONCLUDED 211 Home mixing of fertilizers 211 Kind and amount to buy 212 The crop 213 The soil 215 The system of farming 215 Testing the soil 215

XXIV.--ROTATION OF CROPS 219 Systems of cropping 219 The one crop system 221 Rotation of crops 224 Benefits derived from rotation of crops 230 The typical rotation 231 Conditions which modify the rotation 232 General rules 233 Length of rotation 233

XXV.--FARM DRAINAGE 235 How surplus water affects fertility 235 Indications of a need of drainage 235 Drains: Surface drains Open ditch drains Covered drains or under drains 236 Influence of covered drains on fertility 237 Location of drains: Grade Tile drains 238

GLOSSARY 241

LIST OF ILLUSTRATIONS

The farm equipment--plants, soils, animals, tools, buildings _Frontispiece_

Figure Facing Page

1. Specimen plants for study 6

2. The first effort of a sprouting seed 7

3. Germinating seeds with roots 7

4. To show that plant roots take water from the soil 10

5. To show that plant roots take food from the soil 10

6. A radish root, from which the stored food has been used to help produce a crop of seeds 11

7. A sweet-potato root producing new plants 11

8. Sweet-potato roots 14

9. Soy-bean roots 15

10. A plow stopped in the furrow, to show what it does to the roots of plants when used for after-cultivation 18

11. A corn-plant ten days after planting the seed 19

12. To show where growth in length of the root takes place 22

13. Radish seeds sprouted on dark cloth 22

14. To show how water gets into the roots of plants 23

15. To show osmose 23

16. To show that roots need air 26

17. Comparison of fresh and boiled water 26

18. Comparison of moist sand and puddled clay 27

19. Comparing soils 32

20. Water-test of soils 33

21. To show what becomes of the water taken from the soil by roots 40

22. Percolation experiment. To show the relative powers of soils to take in water falling on the surface 41

23. Bottles used in place of the lamp chimneys in Figs. 22 and 24 44

24. Capillarity of soils. To show the relative powers of soils to take water from below 44

25. Water-absorbing and water-holding powers of soils 45

26. Capillary tubes. To show how water rises in small tubes or is drawn into small spaces 48

27. Capillary plates 48

28. A cone of soil to show capillarity 49

29. To show the relative amounts of film-moisture held by coarse and fine soils 49

30. To show the effect of a soil mulch 56

31. Soil temperature experiment 57

32. Charts showing average temperature of a set of dry and wet soils during a period of five days 60

33. To show the value of organic matter 61

34. Soy-bean roots, showing nodules or tubercles 64

35. Garden-pea roots, showing tubercles or nodules 65

36. To show that seeds need water for germination 72

37. To show that seeds need air for germination 72

38. To show that seeds need air for germination 73

39. A seed-tester: two plates and a moist cloth 80

40. A seed-tester: a plaster cast with cavities in the surface for small seeds 80

41. Germinating corn-kernel and bean 81

42. To show how the bean-plant gets up 82

43. To show how the corn-plant gets out of the soil 82

44. To show the use of cotyledons 83

45. To show the use of the kernel to the young corn-plant 86

46. To show how deeply seeds should be planted 87

47. Operations of seed-planting 88

48. A collection of planting machines 89

49. Spading-fork and spade 92

50. A wood beam-plow 93

51. A slip-nose share and a slip-nose 96

52. A straight knife coulter 96

53. An iron beam-plow with rolling coulter and double clevis 96

54. A rolling cutter-harrow 97

55. Spring-toothed harrows 97

56. Spike-toothed harrows 104

57. A coulter-toothed harrow 104

58. A plank harrow 105

59. To show transpiration 108

60. Amount of transpiration 109

61. To show that growing leaves contain starch 114

62. To show that starch disappears from the leaf when the plant is placed in the dark 114

63. To show that sunlight is necessary for starch-making by leaves 115

64. To show that chlorophyl is necessary for starch formation in the leaf 115

65. To show the giving off of gas by leaves, and that sunlight is necessary for it 118

66. Seedling radishes reaching for light 119

67. Elm leaves injured by the "imported elm-tree leaf-beetle," a chewing insect 119

68. A horse-chestnut stem, showing leaves, buds, and scars, where last year's leaves dropped off 128

69. An underground stem. Buds show distinctly 129

70. Flower of cherry 130

71. Flower of apple 130

72. Pistil and stamen of flowering raspberry 131

73. Flower of buttercup 131

74. A magnolia flower showing central column of pistils and stamens 134

75. Flowers of squash 135

76. Flower of a lily 136

77. Bud and flower of jewel-weed or "touch-me-not" 137

78. Pistillate flower and perfect flower of strawberry 137

79. A crop of cowpeas 178

80. Red clover 179

81. Soy-beans in young orchard 182

82. A young alfalfa plant just coming into flower 183

83. Cross-sections of stone-drains 238

84. Cross-section of a pole-drain and of a tile-drain 238

85. A collection of drainage tools 239

86. A poorly laid tile-drain and a properly graded tile-drain 239