Ch 2. of Water Movement in Soils, Capillary Barriers and Water Movement

00:02:40
https://www.youtube.com/watch?v=eBJEP_wQSa8

الملخص

TLDRWater movement in soil during irrigation is influenced primarily by the attraction of solid surfaces rather than gravity, especially in unsaturated conditions. As soil becomes saturated, gravity takes a more dominant role. The video demonstrates how water moves horizontally and vertically, highlighting that finer soil pores hold water more effectively than coarser sandy layers due to adhesive and cohesive forces. Such sand layers act like a check valve, eventually allowing water passage as the soil wets up. An example is provided from the Columbia Basin, where fine sandy loam over coarse sand and gravel demonstrates increased water retention, supporting better plant growth.

الوجبات الجاهزة

  • 💧 Water moves due to solid surface attraction.
  • 🏞️ Gravity dominates in saturated soils.
  • 🪨 Sand acts as a water check valve.
  • 🌾 Fine sandy loam retains more water.
  • 📈 Coarse layers improve soil water holding capacity.

الجدول الزمني

  • 00:00:00 - 00:02:40

    The movement of water from an irrigation source is influenced more by the attraction to solid surfaces than by gravity, though gravity becomes more significant as the soil gets wetter. Water moves less readily into coarse sand layers due to larger pores, acting as a check valve. This principle explains water flow in filled soils, crucial for agricultural land, such as in Washington State's Columbia Basin, where fine sandy loam retains more water due to underlying coarse sand, enhancing plant growth.

الخريطة الذهنية

Mind Map

الأسئلة الشائعة

  • What affects water movement in unsaturated soil?

    Water movement in unsaturated soil is mainly affected by the attraction of solid surfaces and not gravitation.

  • What happens when the soil becomes saturated?

    When soil becomes saturated, gravitational forces predominate.

  • Why doesn't water move readily into coarse sand?

    Water doesn't move readily into coarse sand because the pores are larger than those in the soil above, which hold water due to greater adhesive and cohesive forces.

  • How do sand layers act in water movement through soil?

    Sand layers act like a check valve, holding back water until the soil becomes very wet, then allowing excess water to pass through.

  • What is the water holding capacity of soil with coarse sand and gravel layers compared to fine sandy loam?

    Soil with coarse sand and gravel layers can retain more than double the amount of water usually held in a fine sandy loam.

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الترجمات
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التمرير التلقائي:
  • 00:00:12
    watch as the water moves out from an
  • 00:00:15
    irrigation pearl
  • 00:00:16
    note that the movement awkward is almost
  • 00:00:18
    as great as that downward this is added
  • 00:00:21
    evident water movement is mainly due not
  • 00:00:24
    to gravitation but to the attraction of
  • 00:00:27
    solid surfaces as the soil becomes
  • 00:00:30
    wetter and wetter however gravitation
  • 00:00:32
    plays a stronger role and if the soil
  • 00:00:35
    becomes completely saturated then
  • 00:00:38
    gravitational forces predominate the
  • 00:00:41
    horizontal layer you see is coarse sand
  • 00:00:44
    one of the important principles of
  • 00:00:46
    unsaturated flow is described as you
  • 00:00:49
    witness what happens as the wedding
  • 00:00:50
    front encounters this layer of coarse
  • 00:00:52
    sand the pores in the soil are many
  • 00:00:56
    times smaller than those between sand
  • 00:00:58
    grains water is held in these small
  • 00:01:00
    pores by large adhesive and cohesive
  • 00:01:03
    forces the pores in the soil are like
  • 00:01:06
    the pores in a piece of blotting paper
  • 00:01:08
    used to soak up ink the huge pores in
  • 00:01:12
    the sand cannot hold water at the
  • 00:01:14
    tensions which exist in the wetted soil
  • 00:01:16
    above so water does not move readily
  • 00:01:20
    into the sand
  • 00:01:21
    however as the soil above the sand
  • 00:01:23
    becomes very wet the water eventually
  • 00:01:26
    moves into the sand just as ink would
  • 00:01:29
    drip from a blotter which is swept
  • 00:01:31
    excessively the sand layers us to act
  • 00:01:33
    something like a check valve holding the
  • 00:01:35
    water back until the soil becomes very
  • 00:01:38
    wet and then letting the excess pass
  • 00:01:40
    through what happens to water in soil
  • 00:01:43
    containing a sand layer is typical in
  • 00:01:46
    principle of what happens to water in
  • 00:01:49
    filled soils for sands and gravels occur
  • 00:01:51
    as layers in finer soil material a great
  • 00:01:55
    deal of agricultural land is
  • 00:01:57
    in this fashion in Washington State's
  • 00:01:59
    Columbia Basin there exists a quarter of
  • 00:02:02
    a million acres of soil composed of one
  • 00:02:04
    to two feet of a fine sandy loam
  • 00:02:06
    overlying coarse sand and gravel the
  • 00:02:10
    ability of this soil to support plant
  • 00:02:12
    growth is greatly affected by the
  • 00:02:14
    presence of course fans and gravel
  • 00:02:16
    because of these course materials the
  • 00:02:19
    overlying soil can retain more than
  • 00:02:21
    double the amount of water usually held
  • 00:02:24
    in a fine sandy loam this is one of the
  • 00:02:27
    best soils in the Columbia Basin
الوسوم
  • water movement
  • soil irrigation
  • gravitational forces
  • adhesive forces
  • Columbia Basin