文档介绍：Charter 5 Soil Water
Section 1
The types of soil water
and measuring soil moisture content
The importance of soil water:
Effect on soil formation,erosion, and structure stability
It is the major constituent of plant protoplasm.
It is essential for photosynthesis and conversion of starches to sugar .
It is the solvent in which nutrients move into and through plant parts.
一、The types and available
of soil moisture
1、Classification of soil water
Adsorbed water
Membranous water
Capillary water
Gravitational water
Numerical method
(1) Soil adsorbed water :
held by strong electrical forces - low energy
little movement- held tight by soil
exists as a film
unavailable to plants
removed from soil by drying in an oven
(2)Soil Membranous water :
held by hydrogen bonding
liquid state in water film
major source of water for plants
greater energy than adhesion water
Sketch map of membranous water
(3) Soil capillary water :
Capillary water-The water held in the “capillary” or small pores of a soil, usually with a tension >60 cm of water.
Capillary water includes capillary hanging water and capillary rise water.
Capillarity:
-1mm
Capillarity obvious
-
Capillarity strong
-
Capillarity very strong
〈
Capillarity disappears
Water is drawn up into the capillary tube
Soil particle
Capillary hanging water sketch map