Transcript 没有幻灯片标题 - Universitas Brawijaya

AIR TANAH
LENGAS TANAH
Soil Water
SOIL MOISTURE
The importance of soil water：
1. Effect on soil formation,erosion, and structure stability
2. It is the major constituent of plant protoplasm.
3. It is essential for photosynthesis and conversion of starches to
sugar .
4. It is the solvent in which nutrients move into and through plant
parts.
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
The types and available
of soil moisture
Classification of soil water
•
•
•
•
Adsorbed water
Membranous water
Capillary water
Gravitational water
•Numerical
method
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Soil adsorbed water ：
1. held by strong electrical forces - low energy
2. little movement- held tight by soil
3. exists as a film
4. unavailable to plants
5. removed from soil by drying in an oven
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Soil Membranous water ：
1. held by hydrogen bonding
2. liquid state in water film
3. major source of water for plants
4. greater energy than adhesion water
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Sketch map of membranous water
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Air Kapiler = 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.
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Air ditarik “naik” ke dalam tabung kapiler
Capillarity：
0.1-1mm
Capillarity obvious
0.05-0.1mm
Capillarity strong
0.05-0.005mm
Capillarity very strong
〈0.001mm
Capillarity disappears
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Air kapiler
dalam pori
tanah
Soil particle
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Kapasitas Lapang (KL) = Field capacity：
Field capacity:
The amount of water remaining in a soil
after the free water has been allowed to
drain away (a day or two) after the root
zone had been previously saturated;
expressed as a percentage.
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Air kapiler
naik ke atas
melalui pori
kapiler
dalam tanah
Soil particle
Groundwater Table
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Ketinggian naiknya air kapiler :
h（cm): the hight of capillary water rise ，d: the
diameter of the capillary tube（mm）
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Air Gravitasi = Gravitational water
Gravitational water
Water which moves into, through, or out of
the soil under the influence of gravity.
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
二、 The express methods of soil water content
（一）The mass water content（m)
Percntage water = {[(wet soil weight)-(oven dry soil weight)]/
(oven dry soil weight)} ×100
（二） The volume water content （ v）
Volume water content = volume of water/bulk volume of
soil=(weight of water/ρW)/(weight of dry soil/ ρb)
V=m·
(三）Relative water content（%）
Relative water content= soil water content/ field capacity
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
（三）Soil water-storage capcity
1、Water deepth（DW）
n
DW=V·h or Dw ,100    1  h
i 1
mm
2、Water fang(方)（ m3）
VFang / ha  10Dw
V
＝2/3D
Fang/mu(亩)
w
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
i
三、Estimating water contents
• Gravimetric method: The soil sample is dried in an
oven at 105°C and the mass of dry soil recorded.
• Neutron scattering method
• Time Domain Reflectometry (TDR)
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Soil Water Potential
Total soil water potential and
individual potentials
Soil A:
Sand
Soil
10%
Soil B:
Clay
Soil
15%
Where does water flow?
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Water moves from areas of high potential
(wet soil : -2 or -4) to areas of low
potential (dry soil -8)
-.4
-3
-7
-8
Root
-2
Soil
Soil
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Soil water potential- The amount
of work that must be done per unit of
a specified quantity of pure water in
order to transport reversibly and
isothermally an infinitesimal quantity
of water from a specified source to a
specified destination.
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
The matric potential（m）
This work is less than zero or negative
work, thus reported in negative values.
The pressure potential （p）
In saturated soil, the pressure potential is
always positive. In an unsatrated field
soil the pressure potential is always zero.
p=wgh
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
The solute (osmotic) potential （S）
The amount of work an infinitesmal quantity of water will do in
moving from a pool of free water the same composition as the soil
water to a pool of pure water at the same location. The solute
potential is usually very small and negative values.
The gravitational potential （g）
The amount of work an infinitesmal amount of pure free
water can do at the site of the soil solution as a result of the
force of gravity.
g =±MgZ
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Soil moisture suction
Absolute positive value
Since soil matric and osmotic potentials are
always negative they are often onsidered as ‘suction’
or ‘tensions’. Suction and tensions are however
always expressed as positive values.
T＝-m 
How do you use suction and
potentials to decide the direction
of soil water movement?
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Soil water potential measurement
The popular unite of the soil water potential is :
Pa
1 Pa=0.0102-cm column of water
1 atmospheres=1033-cm column of
water=1.0133bar
1 bar=0.9896atm=1020-cm column of water
1 bar=105 Pa
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Kurva Karakteristik Air Tanah
The relationship between the soil-water content
(by mass or volume) and the soil-water matric
potential.
S=ab
S=a(/s)b
S=A(s-)n/m
S: suction, Pa; θ:water content; a,b,A,n,m: experience constant.
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Affect the factors
•Texture
Soil moisture suction
•Structure
•Temperature
•Phenomenon of
hysteresis
Clay
Sand
Silt
0 10 20 30 40 50 60 70
Soil moisture content%
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
. Jumlah air dalam zona akar di antara FC dan WP , dan yang dapat digunakan oleh tanaman
disebut “Air Tersedia”. (FC-WP = air tersedia). Untuk tanah-tanah pasir, lempung dan liat , nilainilai (air tersedia) adalah 6, 20 dan 17 persen volume.
SUMBER: http://www.tankonyvtar.hu/en/tartalom/tamop425/0032_talajtan/ch07s05.html
Pergerakan Air dalam Tanah
1.
2.
3.
4.
The principle of water movement in soil
Evaporation
Infiltration
Water redistribution
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Pergerakan Jenuh Air tanah
Saturated flow-The movement of water though a
soil that is temporarily saturated. Most of the water
moves downwards, and some move more slowly
laterally.
The rate of water flow through soil can be described by
Darcy’s Law which states that the flux of water q is
proportional to the hydraulic gradient (the gravitational
potential and the pressure potential )multiplied by the
conductivity or permeability of the soil.
H
q   Ks
L
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Konduktivitas Hidraulik Jenuh (Ks)
The rate of flow through a given amount of soil in a given time equals the
water quantity collected (Qw) divided by both the cross-sectional area of soil
used (A) and the time (t) of measurement.
Qw
Ks  
At
The factors of affect the saturated
hydraulic conductivity:
The characteristics of the saturated
hydraulic conductivity:
•The soil texture
①The saturated hydraulic
conductivity is a constant
•The soil structure
② It is maximum in hydraulic
conductivity
•The amount of organic matter
•The clay mineral
③ It is decided by the soil texture
and the soil structure
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Pergerakan Tidak-Jenuh Air tanah
The movement of water in soil in which the pores
are not filled to capacity with water.
The unsaturted soil water flow is decided by the
matric potential and the gravitational potential.
Darcy’s Law can be extended to describe unsaturated
flow:
d
q   K ( m )
dx
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Konduktivitas Hydraulik
Konduktivitas hidrolik
merupakan fungsi dari
potensial air tanah.
Konduktivitas ini mengukur
kemudahan air untuk
bergerak melalui massa
tanah.
Penurunan konduktivitas
kalau tanah mengering
terutama disebabkan oleh
pergerakan udara ke dalam
tanah untuk menggantikan
air tanah.
SUMBER: http://5e.plantphys.net/article.php?id=39
K(m) :unsaturated hydraulic conductivity
d/dx: water potential gradient
The unsaturated hydraulic conductivity
is a function of soil matric potential.
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Pergerakan uap air dalam tanah
Bentuk-bentuk gerapan uap air dalam tanah:
1. Difusi uap air dalam tanah
2. Koagolasi uap air
Vapor flow can be considered as a diffusion
mechanism in which the driving force is the vapor
pressure gradient.
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Infiltration , water redistribution and evaporation of soil
surface
Soil water infiltration
The entry of water into soil.
Affect the factors：
Velocity of Supply
water
Infiltration rate
SUMBER:
http://croptechnology.unl.edu/pages/informationmodule.php?idinformationmodule=1130447123&topicorder
=3&maxto=13&minto=1
The stable infiltration rate
in several different texture soils ( millimeter/ hour)
Soil
Sand
Sandy
loam
Final
infiltration
rate
>20
10-20
Silt
Clay
Alkalized
clay
5-10
1-5
<1
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Redistribusi Air-Tanah
Redistribution of soil water
The process of soil-water movement to
achieve an equilibrium energy state of water
throughout the soil.
Soil water redistribution is unsaturated flow of soil water.
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Evaporasi (Penguapan) di permukaan tanah
Evaporation: Water lose as vapor from a soil or open water
surface.
1.The keeping the stable stage of evaporation in soil surface
2.The stage of evaporate change with moisture content in soil
surface
3.The stage of water vapor diffusion
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Neraca Air Tanah di Lapangan
Soil water balance in the field can be written as:
W=P+I+U-E-T-R-In-D
P: precipitation; I: irrigation;
E: evaporation; T: transpiration;
R: runoff
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Soil-plant-atmosphere continuum (SPAC)
Water moves from a relatively high potential energy level in the
soil (-100 kPa) and flows down a potential gradient into the plant
root (-500 kPa), plant stem (-800 kPa), and leaves (-1500 kPa),
where it is eventually evaporated into the atmosphere (-10000 kPa).
Desert plants
can live in
-2×106 to
-8×106 Pa.
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
Kontrol Air-Tanah
Ketersediaan Air Tanah
Air Tersedia:
The amount of water released between in
situ field capacity and the permanent
wilting point (usually estimated by water
content at soil matric potential of -1.5
MPa).
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt
.Kurva Retensi Air Tanah
SUMBER: http://www.tankonyvtar.hu/en/tartalom/tamop425/0032_talajtan/ch07s05.html
Kontrol Air Tanah
1.Olah tanah : plow depth, intertillage, roll etc.
2.Mulsa: straw, plastic sheeting etc.
3.Irigasi: drip irrigation, sprinkler irrigation etc.
4.Biological save water .
SUMBER: jpkc.njau.edu.cn/land/ppt/5.soil%20water.ppt