il previously uncropped . . . . . . . . . . 45

23. Pieces of grass, leaves, etc. change to plant food
in the surface soil lint not in the subsoil . . . . . 50

24. Soil in which earthworms have been living and making
burrows . . . . . . . . . . . . . . . . . . . . . . 55

25. Fresh soil turns milk bad, but baked soil does not . . 57

26. Soil contains tiny living things that grow on gelatine 58

27. Our breath makes lime water turn milky . . . . . . . . 59

28. Something in the soil uses up air and makes lime water
turn milky . . . . . . . . . . . . . . . . . . . . . 61

29. Soils are able to stick to water: clay or loam soils do
this better than sands . . . . . . . . . . . . . . . 65

30. Water can pass from wet to dry places in the soil, it
can even travel upwards . . . . . . . . . . . . . . 66

31. Plants growing in soils supplied from below with water.
All the water the plants get has to travel upwards 67

32. Mustard growing in soils supplied with varying
quantities of water . . . . . . . . . . . . . . . . 69

33. Wheat growing in moist and in dry soils . . . . . . . 71

34 _a_ and _b_. Plants found on a dry soil had
narrow leaves, those on a moist soil had wider
leaves. _Phot._ S. T. Parkinson . . . . . . . . . 72, 73

35. Plants give out water through their leaves . . . . . . 74

36. Stephen Hales's experiment in 1727 . . . . . . . . . . 75

37. Hill slope near Harpenden showing woodland at top and
arable land lower down. _Phot._ Lionel Armstrong 77

38. View further along the valley; woodland and arable
above, rough grassland near the river.
_Phot_. Lionel Armstrong . . . . . . . . . . . . . . 79

39. Rough grass pasture near the river. Higher up is
arable land. _Phot._ Lionel Armstrong . . . . . . . 81

40. After harvest the farmer breaks up his land with a
plough and then leaves it alone until seed time.
_Phot._ Lionel Armstrong . . . . . . . . . . . . . . 83

41. Rolling in mangold seed on the farm.
_Phot._ H. B. Hutchinson . . . . . . . . . . . . . . 85

42. Soil sampler . . . . . . . . . . . . . . . . . . . . . 88

43. Cultivation and mulching reduce the loss of water
from soils . . . . . . . . . . . . . . . . . . . . . 90

44 _a_ and _b_. Maize cannot