Better Farming Series 28 - Water: Where Water Comes from (FAO, 1981, 31 p.) Water in the ground (introduction...) Water and the soil Water and the subsoil Water and parent rock

Better Farming Series 28 - Water: Where Water Comes from (FAO, 1981, 31 p.)

Water in the ground

55. The ground is made up of several different layers. To know how water goes into the ground, let us first look at these layers (see Booklet No. 4, pages 6 to 10).

56. The top layer is the soil. This layer may be very deep or it may be quite shallow. The roots of smaller plants get their water here.

57. Below the soil is the subsoil. The subsoil is much harder than the soil. The roots of larger plants and trees get their water here.

58. Below the subsoil we find stone or rock. This is called parent rock.

The parent rock

Water and the soil

59. If the soil has very much sand in it, water sinks in quickly and easily.

Water sinks quickly

60. Little water stays on the surface of sandy soils. Because sand has poor texture sandy soils held little water.

61. If the soil has very much clay in it, water does not sink in quickly or easily.

Water does not sink quickly

62. It takes a long time for water to go into clay soils and the more clay there is in the soil, the longer it takes. Because clay has good texture, clay soils held very much water.

63. Some of the water that sinks into the ground is held in the soil.

64. Part of this water is used by plants and part evaporates from the soil at the surface.

65. When water is not held in the soil and used by the plants or evaporated from the surface, it seeps down into the subsoil.

Water seeps down into the subsoil

Water and the subsoil

66. how fast and how deep water goes into the subsoil depends on the structure of the subsoil.

67. Sometimes the subsoil is very hard and holds little water.

Little water is holded in the subsoil

68. Sometimes the subsoil is soft and has a structure that holds water well.

Subsoil holds water well

Water and parent rock

69. If the parent rock that lies below the subsoil is solid and unbroken, water stays on top of the rock

Water stays on top of the parent rock

70. If the rock layer is not too far below the surface, it is not hard to reach this water.

71. If the parent rock that lies below the subsoil is broken, water can sink deep into the rock and becomes hard to reach.

Water sinks deep into the rock