DASAR ILMU TANAH
UDARA TANAH DAN
AERASI
Oleh:
Prof Dr.IR.Soemarno,M.S
.
Jurusan Tanah FP UB Febr 2012
UDARA TANAH
Udara yang berada dalam ruang pori‐pori
tanah (merupakan fraksi gas dalam sistem
dispersi)
Fungsinya : sebagai sumber : O2 , CO2 , N2
O2 : untuk pernafasan akar, mikroorganisme
& jasad/hewan dalam tanah
CO2 : untuk dekomposisi & pelarutan hara
N2 : sebagai suplai n tanah
O2 penting dalam tanah : kadarnya ≥ 10%
The air and other gases in spaces in the soil;
specifically, that which is found within the zone of
aeration. Also known as soil atmosphere.
http://www.answers.com/topic/soilair#ixzz1mP6ZjavG
…. Diunduh 14/2/2012
KEPEKAAN TANAMAN
Kepekaan tanaman terhadap O2 tanah/aerasi :
Tanaman yg sangat peka thdp O2
tanah/kondisi aerasi : tomat, kentang, kapri,
gula bit
Tanaman yg peka : jagung, gandum, kedelai
Tanaman yg resisten : rumput‐rumputan
Tanaman yg sangat resisten : padi‐padian
If there is no air in the soil, the organic matter in the soil
will begin to rot.
It is called anerobic decomposition.
Air in the soil allows for drainage, gives roots a place to
grow, and keeps methane from building up by allowing
it a ready escape.
http://wiki.answers.com/Q/How_is_soil_air_important#i
xzz1mP6xpcrT
…. Diunduh 7/2/2012
AERASI TANAH
Pengharkatan kondisi aerasi :
Porositas total : jumlah total pori tanah ( yg
terisi udara & air) dinyatakan dlm % volume
tanah (jmlh pori mikro & makro)
Volume total tanah :
Vs + Va + Vw = 1
1 – Vs = Va + Vw
Va + Vw = porositas total ( n )
n = ( 1 – bv/bj ) x 100%
It is important for air to get into soil, as plants
need oxygen to survive. Without air, plants
would die, and therefore disrupt the food wed
of the environment it is in.
http://wiki.answers.com/Q/Why_is_it_importan
t_for_air_to_get_into_soil#ixzz1mP7KzWEA
…. Diunduh 7/2/2012
KAPASITAS UDARA EFEKTIF
Kapasitas udara/aktual/efektif :
bagian ruang pori tanah yang terisi udara,
dinyatakan dalam % volume tanah
n – Vw = { n – (%KL x BV)}
Vw = %KL x BV
Kapasitas udara selalu berfluktuasi tergantung :
KL tanah
Struktur tanah
Permukaan air tanah (GROUNDWATER)
Soil Pore
For plant roots and animals to move through it and
for the animals to breath.
It is important because the microorganisms living in
under the soil take these oxygen.It is also important
for anaerobic respiration.You will also find that the
earthworms live under the soil takes oxygen deep
below in the soil.
http://wiki.answers.com/Q/Why_is_it_important_for_soil_to_
have_air_spaces_in_it#ixzz1mP7erq1X
…. Diunduh 14/2/2012
KAPASITAS AERASI TANAH
Kapasitas aerasi/porositas aerasi/porositas non
kapiler :
yaitu kapasitas udara pada saat
lengas tanah mencapai kapasitas lapang
(persen total pori non kapiler/makro)
Kapasitas aerasi = n – (KL KAP. LAP. X BV)
Soil porosity (f) is the ratio of pore volume (Vf) to
total soil volume (Vt)
f = Vf / Vt
It is generally between 30-60%. Porosity tells us
nothing about the relative amounts of large and
small pores, and should be interpreted with caution.
Generally, high porosity (e.g. 60%) is an indicator
of lack of compaction and good soil conditions.
http://www.landfood.ubc.ca/soil200/components/air.htm….
Diunduh 7/2/2012
FAKTOR KOMPOSISI UDARA TANAH
Faktor‐faktor yang mempengaruhi komposisi
udara tanah :
Iklim
Sifat tanah seperti tekstur, struktur, tinggi permukaan
air tanah
Sifat tanaman
Keterdapatan tanaman mengurangi kadar O2
dan menambah CO2, bo dan kegiatan jasad
renik CO2 > (jika aerob), CH4 > (jika anaerob).
The composition of soil air is different from that of the
atmosphere because it cannot readily mix with air above the soil.
The metabolic activity of plant roots, microbes and soil fauna all
affect the composition of soil air.
For example, the concentration of carbon dioxide (CO2) in soil
(between 0.3 and 3%) is often several hundred times higher than
the 0.03% found in the atmosphere. In extreme cases oxygen can
be as low as 5-10%, compared to 20% in the atmosphere. Soil air
has a higher moisture content than the atmosphere, with relative
humidity approaching 100% under optimum conditions.
(humidity is not as variable in soil as it is in the atmosphere).
The amount and composition of air in soil are dynamic and to a
large degree are determined by water content and activity of soil
organisms.
http://www.landfood.ubc.ca/soil200/components/air.htm….
Diunduh 7/2/2012
KOMPOSISI UDARA TANAH
Tergantung dari proses biologi serta sukar
mudahnya tukar menukar dengan udara
atmosfer
Contoh udara tanah sawah yang bebas air
…. Diunduh 7/2/2012
Secara riil komposisi udara tanah dibanding
udara atmosfer, sebagai berikut
Growth of most plants and survival of their roots normally
requires maintenance of adequate soil oxygen.
This in turn requires maintainance of soil water well below
saturation, to enable rapid gas diffusion in the soil.
…. Diunduh 7/2/2012
PERTUKARAN UDARA
Komposisi tersebut selalu berubah‐ubah
tergantung beberapa faktor yaitu :
Kecepatan pertukaran udara tanah dan
atmosfer, tergantung :
o Tanah : tekstur, struktur, B.O, KL, suhu
o Iklim : angin, tekanan udara, & suhu
o Kedalaman dari muka tanah
The exchange of gases between the atmosphere and soil is
facilitated by two mechanisms:
(1) Mass flow (convection) of air - the moving force is a
gradient of total gas pressure, and it results in the entire mass
of air streaming from a zone of higher pressure to one of
lower pressure. Mass flow of air is much less important than
diffusion, except perhaps in layers at or very near the soil
surface.
(2) Diffusion - moving force is gradient of partial pressure of
any constituent member of air to migrate from a zone of
higher to lower pressure, even while air as a whole may
remain stationary. In other words, through diffusion each gas
moves in a direction determined by its own partial pressure.
http://www.landfood.ubc.ca/soil200/components/air.htm….
Diunduh 7/2/2012
Pertukaran Udara Tanah/Pembaruan
Komposisi Udara Tanah
Pertukaran udara tanah & udara atmosfer dapat
terjadi karena adanya gerakan udara.
Ada 3 faktor yg mempengaruhi pembaruan
udara dalam tanah; yaitu :
Proses difusi
Aliran masa gas
Air hujan
The oxygen flux density due to diffusion is proportional to
the oxygen concentration gradient along the axis, and the
proportionality factor is called the (oxygen) diffusion
coefficient (D). This statement is an example of Fick’s
Law of Diffusion, which can be expressed as follows:
J = - D dC/dX
where J is the diffusive flux density of the gas (oxygen in
this example) (mg/m2/s) along the x-axis, C is oxygen
concentration in the soil air (units are g/m3), x is distance
along x-axis (m), dC/dx is the oxygen concentration
gradient (g/m4), and D is the (oxygen) diffusion coefficient
(m2/s).
http://www.landfood.ubc.ca/soil200/components/air.htm….
Diunduh 7/2/2012
DIFUSI GAS
Gerak acak molekul‐molekul gas, yg
terjadi karena perbedaan tekanan parsiil
masa-masa gas, namun tekanan total
sama
Untuk terjadinya proses difusi ini, di dlm
tanah harus tersedia cukup
ruang/pori‐pori efektif
The oxygen diffusion coefficient (D) for diffusion in air is about
10,000 times as large as the coefficient for diffusion in water.
Thus the oxygen diffusion coefficient (D) of a soil is very
strongly influenced by three factors:
(1) air-filled porosity (Va/Vt), which decreases with increasing
soil water content
(2) the continuity of air-filled pores, which decreases with
increasing soil water content
(3) the tortuosity of air-filled pores, which increases with
increasing soil water content.
http://www.landfood.ubc.ca/soil200/components/air.htm….
Diunduh 7/2/2012
ALIRAN MASSA GAS
Aliran Massa Gas
terjadi karena perbedaan tekanan total
udara dalam tanah dan udara atmosfer, hal ini
terjadi kalau :
Suhu tanah berubah
Lengas tanah
Kecepatan angin di atas tanah berubah
http://www.hissan.co.jp/business/moda/e_index.html ….
Diunduh 14/2/2012
AIR HUJAN
Air hujan dapat memperbarui komposisi
udara tanah karena air hujan mengandung O2
Dalam 1 cm air hujan dengan luasan 1 ha
lahan dapat mengandung ± 4000 gram O2
(100000 liter air hujan ~ ± 4000 gram O2)
…. Diunduh 14/2/2012
PENGARUH AERASI (TATA UDARA) DALAM
TANAH
Perbaikan aerasi tanah akan berpengaruh terhadap :
Peningkatan kegiatan M.O
Peningkatan penguraian B.O
Peningkatan strukturisasi
Pencegahan terbentuknya senyawa TOKSIK :
Methan
Amonia
H2S
N2
Nitrit
Senyawa‐senyawa ferro
…. Diunduh 14/2/2012
PENGELOLAAN UDARA TANAH
Pengelolaan udara tanah ditujukan untuk
mempercepat proses difusi dan aliran
massa gas, dengan usaha :
Perbaikan struktur tanah
Pengendalian lengas tanah
http://www.uraniumresources.com/isr-technology/photo-gallery
…. Diunduh 14/2/2012
UDARA TANAH - PENGELOLAAN
Tindakan‐tindakan yang dapat dilakukan :
Menghindari terbentuknya lapisan cadas
serta pemampatan tanah
Pengolahan tanah yang tepat
Penambahan B.O. ke dalam tanah
Pemberian mulsa
Perbaikan drainase.
http://www.extension.org/pages/18634/use-of-tillage-in-organicfarming-systems:-the-basics …. Diunduh 14/2/2012
AERASI
TANAH
Tanah yang AERASI nya baik adalah
tanah yg mengandung gas tersedia dalam
jumlah dan perbandingan yang tepat bagi
jasad aerobik yang hidup dan mampu
menunjang berlangsungnya proses
metabolik yg esensial bagi jasad tsb pd
kecepatan yg optimum
Tanah yang AERASI nya baik mempunyai sifat:
1. Harus ada ruangan yang cukup tanpa bahan
mineral dan air
2. Harus ada kesempatan yg cukup bagi gas-gas untuk
keluar-masuk ruangan tsb
Dua reaksi biologis yg terkait dgn dinamika O2 dan CO2
dalam tanah:
1. Pernafasan akar tumbuhan tinggi
2. Dekomposisi bahan organik tanah secara aerobik oleh jasad
renik.
(C) + O2
CO2
MASALAH
AERASI
TANAH
Penyebab buruknya aerasi tanah:
1. Kandungan air tanah yg berlebihan shg
tidak menyisakan ruangan untuk gas/
udara
2. Pertukaran gas tidak cukup cepat unt
mempertahankan kadarnya pd tingkat
tertentu.
Air Tanah yang berlebihan
1. Tanah jenuh air, tanah tergenang dapat
berpengaruh buruk pd tanaman pd umumnya
2. Biasanya pd tanah-tanah yg drainasenya buruk
dan tekstur halus
3. Pada tempat-tempat cekungan
PERTUKARAN GAS antara tanah dan atmosfer tgt pd:
1. Laju reaksi biokimia yg mempengaruhi gas dlm tanah
2. Laju ke luar - masuknya gas-gas dari dan ke dalam tanah.
Pertukaran gas ini terjadi melalui mekanisme:
1. Pergerakan masal (mass flow)
2. Difusi gas
LAJU
DIFUSI
OKSIGEN
(LDO)
LDO adalah laju pergantian oksigen dalam
tanah yg dipakai oleh akar tanaman yg
bernafas atau digantikan oleh air.
Nilai LDO semkin kecil dengan kedalaman tanah
LDO pada kedalaman 95 cm sama dengan setengah
nilai LDO pd kedalaman 11.5 cm
Pertumbuhan akar tanaman berhenti bila LDO turun
menjadi 20 g x 10-8 cm2/menit
SUSUNAN
UDARA
TANAH
Udara tanah umumnya lebih kaya CO2 dan
uap air , gas metan dan H2S dibandingkan
dengan udara atmosfer.
Sejumlah gas-gas tertentu dapat larut dalam
air tanah dan diikat oleh permukaan koloid
tanah, misalnya oksigen
Tempat
O2
% volume:
CO2
N2
Udara tanah:
New York
15.10
4.50
20.65
0.25
81.40
Inggris
79.20
Udara Atmosfer
Inggris
20.97
79.00
Sumber: Lyon, Buckman & Brady, 1952.
Faktor
Susunan
Udara
Tanah
Susunan udara tanah tgt pada:
1. Jumlah ruangan / pori yg
tersedia
2. Kecepatan reaksi biokimia
3. Pertukaran gas
Penambahan
bahan
organik
akan
mengubah susunan udara tanah
Tanah lapisan atas vs Tanah lapisan bawah
Jumlah total ruangan pori tanah lapisan bawah lebih
sedikit dibanding tanah lapisan atas
% CO2 udara tanah
sampling, cm
0.5
gandum + rabuk
Kedalaman
30
tanah bera + rabuk kandang
Lempung liat berdebu
Lempung berdebu
tanah bera
180
Waktu sampling
10
20 % O2 udra tnh
AERASI &
KEGIATA
N
BIOLOGIS
Jasad Mikro
1. Aerasi buruk menurunkan oksidasi bahan
organik tanah
2. Penurunan ini lebih disebabkan oleh
kekurangan O2
3. Populasi jasad renik sangat terpengaruhi
olh aerasi
4. Aerasi buruk mendorong aktifitas jasad
anaerob dan fakultatif, menghasilkan
senyawa reduksi, fero, mangano, sulfida
Aerasi b uruk mempengaruhi Tanaman:
1. Pertumbuhan perakaran sangat terbatas
2. Penyerapan hara terhambat
3. Air menjadi berkurang
4. Pembentukan senyawa anorganik yang bersifat
toksik
Akar tanaman apel memerlukan minimal 3% O2 dalam udara
tanah , sedangkan 5 - 10% cukup untuk pertumbuhan akar.
Minimal diperlukan udara tanah yg mengandung 12% O2
untuk pertumbuhan akar-akar baru.
Pertumbuhan tajuk tanaman normal selama LDO lebih dari
30-40 g x 10-8 /cm2/menit.
AERASI &
EFEK
LAIN
Tanaman
Dekomposisi anaerobik
C6H12O6
gula
Tekstur
3CO2 + 3 CH4
metan
LDO pada kedalaman:
10 cm 20 cm
30 cm
Brokoli
Lempung
Selada
Lempung berdebu
Phaseolus sp
Lempung
Arbei
Lempung berpasir
Kapas
Lemping berliat
Jeruk
Lempung berpasir
53
49
27
36
7
64
31
26
27
32
9
45
Kondisi
pertumbuhan
tanaman
38 Sangat baik
32 Baik
25 Klorosis
34 Klorosis
Klorosis
39 Pertumbuhan akar
cepat
Sumber: Stolzy dan Letey, 1964.
Kondisi aerasi tanah berpengaruh terhadap bentuk unsur hara penting:
Unsur
Kondisi Oksidasi
Karbon
Nitrogen
Belerang
CO2
NO3SO4=
Kondisi reduksi (tergenang)
CH4
N2, NH4+
H2S, S=
AERASI &
KEGIATAN
Pengelolaan
Tindakan untuk memperbaiki aerasi
ntanah:
1. Menghilangkan air yang berlebihan
(drainase)
2. Memperbaiki agregasi dan pengolahan
tanah
Adaptasi Tanaman-Tanah :
1. Pohon buah-buahan dan tanaman berakar dalam
memerlukan solum tanah yang dalam (tebal),
aerasinya baik, dan sangat peka terhadap
kekurangan oksigen dalam tanah
2. Pengelolaan tanaman ditentukan oleh baikburuknya aerasi tanah
SUHU
TANAH
Suhu tanah sangat vital bagi aktivitas
biologis
dalam
tanah,
termasuk
pertumbuhan akar tanaman.
Proses nitrifikasi baru dapat berlangsung
kalau suhu tanah telah mencapai 5oC, batas
optimumnya 27 - 33oC
Suhu tanah di lapangan
ditentukan oleh:
1. Jumlah panas yang
diserap oleh tanah
2. Energi panas yg
diperlukan
untuk
mengubah
suhu
tanah
3. Energi yg diperlukan
untuk evaporasi yg
terus menerus di
permukaan tanah
Amplitude of seasonal soil
temperature change as a
function of depth below
ground surface.
Sumber: http://www.geo4va.vt.edu/A1/A1.htm
SERAPAN
&
KEHILANG
AN PANAS
Jumlah panas yg diserap tanah ditentukan oleh
radiasi efektif yg mencapai permukaan tanah
dan iklim
Jumlah energi yg masuk tanah dipengaruhi oleh:
1. Warna tanah: gelap menyerap lebih banyak
energi
2. Lereng:
3. Tanaman penutup tanah: Hutan vs. tanah
gundul
Tanah gundul lebih cepat memanas dan mendingin
Kehilangan panas dari tanah ke atmosfer, melalui KONDUKSI dan RADIASI
Radiasi ini berupa infra merah, tidak terlihat mata, gelombang gelap
Radiasi gelombang gelap ini berenergi tinggi dan selama pemancarannya
banyak panas yg hilang dari tanah
Thermal Admittance (λ/Cv) 1/2 : Represents ability of soil to accept and
release heat.
Soils with low thermal admittance have extreme surface temperature
fluctuations. Because water has a HIGH heat capacity and is a GOOD
conductor, wet soils will have a HIGH thermal admittance..
Thermal Admittance
Source: Lesley Dampier
PANAS
JENIS
TANAH
Panas jenis tanah: Jumlah panas yang
diperlukan oleh satu gram tanah untuk
menaikkan suhunya satu derajat celcius.
Panas jenis tanah kering lebih rendah
dibandingkan dg tanah basah
Tanah kering
: PJ = 0.20
Kadar air 20%
: PJ = 0.33
Kadar air 30%
: PJ = 0.38
Thermal Conductivity (λ): Measure of the ease with
which a soil transmits heat. It describes heat flow in
response to a temperature gradient..
Thermal Conductivity
Source: Lesley
Dampier
PANAS
PENGUAP
AN
Penguapan air tanah memerlukan sejumlah
energi panas
Untuk menguapkan 1 g air pada 20oC
diperlukan panas 585 kalori.
Penguapan 0.452 g air memerlukan 265
kalori.
Bila semua panas ini diambil dari tanah dan
air, maka tanah sedalam 30 cm menjadi
dingin dan suhunya sama dengan -2oC.
Warna tanah vs. Suhu
Tanah gelap biasanya kaya bahan organik dan
kandungan airnya tinggi.
Tanah gelap yg drainasenya buruk lambat memanas.
Soil Heat Capacity (Cv): Amount of heat needed to cause a
1oC change in temperature of a unit volume of soil.
Soils with high Cv are
buffered against temperature
change .
It is much easier to raise soil
temperature by 1oC in a dry
soil than wet soil
Heat Capacity
Source: Lesley
Dampier
GERAKAN
PANAS
DALAM
TANAH
Energi panas masuk ke dalam tanah melalui
proses konduksi, sehingga kadar air tanah
sangat menentukan laju konduksi ini.
Energi panas lebih mudah menjalar dari tanah ke
air dibandingkan dari tanah ke udara
Proses konduksi panas dalam tanah berlangsung lambat. Tanah
lapisan bawah suhunya lebih rendah dp tanah lapisan atas.
Perubahan suhu tanah lapisan bawah sangat sedikit sekali
Thermal Diffusivity (λ/C): An indication of subsurface
temperature response to surface temperature change.. Soils with
high thermal diffusivity undergo large and rapid subsurface
temperature responses to surface temperature change.. Does not
change much with water content in organic soil, but in mineral
soils, the peak thermal diffusivity occurs near field capacity
Heat Capacity
Source: Lesley
Dampier
Suha tanah pada suatu saat tergantung pada
nisbah energi panas yang diserap dan
yang hilang
Suhu tanah juga tergantung kedalaman
tanah
SUHU
TANAH
Suhu tanah. oC
15
20
25
30
35
Soil
depth
cm 60
Januari
300
1956 (Texas)
Juli
Sumber:
Fluker,
Pengendali
an Suhu
Tanah
Penggunaan mulsa organik mengakibatkan
suhu tanah lebih rendah dan lebih merata
Pengelolaan air tanah secara tepat juga
akan mempengaruhi suhu tanah
Suhu
oC
Kedalaman tanah 1.5 cm
15 cm
38
Kedalaman tanah
tanpa mulsa
Dengan mulsa
Tanpa
mulsa
Dengan
mulsa
pagi
sore
sore
pagi
AERASI TANAH : Kemampuan tanah untuk
melakukan pertukaran gas dengan atmosfer.
Proses aerasi tanah ini melibatkan laju ventilasi,
Komposisi udara tanah, proporsi pori tanah yang
terisi dengan udara, dan potensial reaksi redoks
Micropores (d<0.08mm) occur within aggregates. They
are usually filled with water and are too small to allow
much movement of air. Water movement in micropores
is extremely slow and much of the water held by them is
unavailable to plants.
Sumber:
http://www.landfood.ubc.ca/soil200/interaction/water_air.
htm
‘Goose’ Your Lawn for Good
Soil Health
By Shayne Hale June 2, 2011
Aeration is essential and fairly
simple to do. Most rental
centers have a lawn aerator
that they will rent out by the
day or perhaps by the hour.
This machine is simply a large
drum with spikes or tubes
around the drum. Usually gas
powered, this machine
removes “plugs” of soil,
thereby allowing the soil to
breathe, and decreases soil
compaction, which increases
microbial action in the soil.
Also, lawn aerating promotes
deeper root growth and, in
time, a healthier lawn with
fewer weeds. A healthy, robust
lawn should choke out
intruders.
Sumber: http://anewscafe.com/2011/06/02/goose-your-lawn-for-good-soilhealth/
Lawn Aeration for a Greener, Thicker, Healthier
Lawn!
More Benefits of Lawn
Aeration
Aeration loosens compacted soil
and breaks up thatch. It allows
water and other nutrients to seep
into the soil, encouraging new root
growth and establishing a stronger,
deeper root base for a lusher,
healthier turf. Another benefit of
aeration is the reduction of water
runoff and puddling.
Lawn Aeration permits the root
system to go deeper where the
ground temperature is cooler and
moister, allowing the grass to stay
greener longer in the heat of the
summer.
Remember, 90% of grass is in the
roots!
A healthy root system is a must for
an attractive lawn. Oxygen in the
soil is vital for healthy roots. Root
growth is inhibited by clay and
compacted soils because of a
restricted oxygen supply. Aerating
improves rooting and problem soils
by allowing air into the soil.
Umber: http://yardplug.com/FAQ/FAQ1.htm
Sumber: organicsoilsolutions.com
Pemadatan
tanah berarti
tanah menjadi
lebih padat,
porositasnya
berkurang,
sehingga
jumlah dan
pergerakan
udara dalam
tanah juga
terbatas.
Hal ini dapat
mengganggu
pertumbuhan
akar tanaman
Mechanism of Gas Exchange in Soils:
Mencegah defisiensi O2 atau toksisitas CO2
Mekanisme pergerakan gas
Mass Flow
Movement of a mass of air (gases
move together
Driven by gradients in total
pressure differences
Caused by changes in temperature
(ideal gas law)
Caused by movement of water
downward
Diurnal flow of air in upper few
inches (soil breath?)
Diffusion
Each gas moves down gradients of its
own concentration
Even with no overall pressure
difference
O2 and CO2 diffusing past each
other in opposite directions
Sumber;
http://faculty.plattsburgh.edu/robert.fuller/370%20Files/Weeks13Soil%20Air%20&%20Tem
p/aastart14.htm
Function of concentration gradient and resistance
Resistance: Increases with reductions in pore size
O2 gradient: Decreases with depth due to O2 consumption
Gradient decreases with depth; less ODR.
O2 Diffusion rate (ODR) :
Rate of movement across a cross-sectional area ;
O2/cm2.minute
ug
Sumber;
http://faculty.plattsburgh.edu/robert.fuller/370%20Files/Weeks13Soil%20Air%20&%20T
emp/aastart14.htm
Faktor-faktor yang mempengaruhi Aerasi
1.
Excess Moisture diffusion of water
very slow through
water
2.
Soil texture - heavy
soils - reduced pore
size, greater
resistance
3. Poor Structure macropores increase
ODR
4. Position on Slope excess moisture at
bottom
5.
Impermeable Layers
6.
Soil Depth - subsoils
farther away from
surface (less ODR)
7.
Rate of O2 consumption
(high labile OM content)
Sumber;
http://faculty.plattsburgh.edu/robert.fuller/370%20Files/Weeks13Soil%20Air%20&%20T
emp/aastart14.htm
POTENSIAL REDOKS (Eh)
Measured with a platinum
(redox) electrode attached to
a pH meter. Ranges from 400 millivolts (reducing) to
+600 mV (oxidizing
conditions) Measure of the
relative concentration of
reduced vs. oxidized forms
Reduced forms have
available electrons, carried
by H, or less positive
charge;
Oxidized forms have more O,
or higher positive charge
Sensitive roots are adversely
affected below +300 mV
Other plants are tolerant
(adaptations, such as
aerenchyma)
As O2 availability
declines: step down through
bacteriological reactions
using alternate oxidants.
Sumber;
http://faculty.plattsburgh.edu/robert.fuller/370%20Files/Weeks13Soil%20Air%20&%20Tem
p/aastart14.htm
Structure of soil, indicating presence of bacteria, inorganic,
and organic matter, water, and air. Image from Purves et al.,
Life: The Science of Biology, 4th Edition, by Sinauer
Associates (www.sinauer.com) and WH Freeman
(www.whfreeman.com).
Posisi dan lokasi udara
dalam pori, di dalam
struktur tanah
Macropores
(d>0.08mm) occur
between aggregates
(interped pores) or
individual grains in
coarse textured soil
(packing pores) and
may be formed by soil
organisms
(biopores). They allow
ready movement of air
and the drainage of
water and provide space
for roots and organisms
to inhabit the soil.
SUMBER:
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPLANTHOR
M.html
TEKSTUR TANAH:
THE KEY TO MANAGEMENT OF SOIL – PLANT – WATER
RELATIONSHIP
Soil is the
voluminous upper
part of the earth crust
that consists of
unconsolidated
inorganic particles
and organic
fragments with pore
spaces between and
within them.
Pore spaces contain
soil air, and soil
solution.
In other words, soil
volume consists of
solid, liquid
and gaseous phases.
.SUMBER: http://www.ecoconsulting.com/balance.htm
Perbandingan antara komposisi udara tanah
dan atmosfir
Sumber:
http://www.ctahr.hawaii.edu/mauisoil/a_comp04.aspx
Kandungan O2 dan CO2 pada berbagai kedalaman
tanah (Trinidad)
Sumber:
http://www.ctahr.hawaii.edu/mauisoil/a_comp04.aspx
UDARA TANAH
Air can fill soil pores as water drains or is removed
from a soil pore by evaporation or root absorption.
The network of pores within the soil aerates, or
ventilates, the soil.
This aeration network becomes blocked when water enters
soil pores. Not only are both soil air and soil water very
dynamic parts of soil, but both are often inversely related:
1.
2.
3.
An increase in soil water content often causes a reduction
in soil aeration.
Likewise, reducing soil water content may mean an
increase in soil aeration.
Since plant roots require water and oxygen (from the air
in pore spaces), maintaining the balance between root
and aeration and soil water availability is a critical aspect
of managing crop plants.
Sumber:
http://www.ctahr.hawaii.edu/mauisoil/a_comp04.aspx
ARTMOSFER TANAH
The soil atmosphere is not uniform throughout the soil
because there can be localized pockets of air.
The relative humidity of soil air is close to 100%, unlike most
atmospheric humidity.
Air in the soil often contains several hundred times more
carbon dioxide.
Sumber: http://www.ctahr.hawaii.edu/mauisoil/a_comp04.aspx
KOMPONEN UTAMA TANAH ADALAH:
Air, Udara, Rocks, Minerals, Nutrients, Organic
Matter, Well-decomposed organic matter – Humus,
Organisms
The spaces between the
solids are called pores.
Good soil contains lots of
these and is described as
porus.
This way air can easily
circulate through the soil
to reach plant roots and
allow water to drain
easily.
The solid portion is
mostly rock particles and
bits of dead material and
organic matter.
Sumber: http://www.blogdivvy.com/growing-vegetables/what-issoil.htm
SIFAT OLAH TANAH
Soil tilth is a measurement of
the balance between basic soil
elements: mineral, air, water
and organic matter.
The proper balance of these
elements increases soil
production by allowing
efficient interaction of all the
soil systems.
Air and water balance in the
soil is the key to good root
growth.
Sumber: http://rbmc.com.au/aerway.htm
PORI DAN UDARA TANAH
Soil pores, the voids
between minerals, organic
matter, and living organisms,
are filled with air or water.
There is a dynamic
equilibrium between water
and air content within a soil.
When water enters the soil,
it displaces air from some of
the pores.
1. Composition of soil air
2. Movement of gasses
within soil
3. Soil porosity
Source: Lesley
Dampier
Sumber:
http://www.landfood.ubc.ca/soil2
00/interaction/water_air.htm
Sumber:
http://www.landfood.ubc.ca/soil2
00/components/air.htm
KOMPOSISI UDARA TANAH
The composition of soil air is different from that of
the atmosphere because it cannot readily mix with
air above the soil. The metabolic activity of plant
roots, microbes and soil fauna all affect the
composition of soil air.
For example, the concentration of carbon dioxide
(CO2) in soil (between 0.3 and 3%) is often several
hundred times higher than the 0.03% found in the
atmosphere. In extreme cases oxygen can be as low
as 5-10%, compared to 20% in the atmosphere. Soil
air has a higher moisture content than the
atmosphere, with relative humidity approaching
100% under optimum conditions. (humidity is not
as variable in soil as it is in the atmosphere).
The amount and composition of air in soil are
dynamic and to a large degree are determined by
water content and activity of soil organisms.
Sumber: http://www.landfood.ubc.ca/soil200/components/air.htm
PERGERAKAN GAS DALAM
TANAH
Ada dua mekanisme yang memfasilitasi pertukaran
gas antara TANAH dan ATMOSFIR:
1) MASS FLOW (convection) of air - the
moving force is a gradient of total gas pressure,
and it results in the entire mass of air streaming
from a zone of higher pressure to one of lower
pressure. Mass flow of air is much less important
than diffusion, except perhaps in layers at or very
near the soil surface.
2) DIFFUSION - moving force is gradient of
partial pressure of any constituent member of air to
migrate from a zone of higher to lower pressure,
even while air as a whole may remain stationary. In
other words, through diffusion each gas moves in a
direction determined by its own partial pressure.
Sumber: http://www.landfood.ubc.ca/soil200/components/air.htm
PERGERAKAN GAS DALAM
TANAH
The oxygen flux density due to diffusion is proportional to
the oxygen concentration gradient along the axis, and the
proportionality factor is called the (oxygen) diffusion
coefficient (D).
This statement is an example of Fick’s Law of Diffusion,
which can be expressed as follows:
J = - D dC/dX
where J is the diffusive flux density of the gas (oxygen in this
example) (mg/m2/s) along the x-axis,
C is oxygen concentration in the soil air (units are g/m3), x is
distance along x-axis (m), dC/dx is the oxygen concentration
gradient (g/m4), and
D is the (oxygen) diffusion coefficient (m2/s).
Sumber: http://www.landfood.ubc.ca/soil200/components/air.htm
PERGERAKAN GAS DALAM
TANAH
The oxygen diffusion coefficient (D) for diffusion in air is
about 10,000 times as large as the coefficient for diffusion in
water.
Thus the oxygen diffusion coefficient (D) of a soil is very
strongly influenced by three factors:
1) air-filled porosity (Va/Vt), which decreases with
increasing soil water content
2) the continuity of air-filled pores, which decreases with
increasing soil water content
3) the tortuosity of air-filled pores, which increases with
increasing soil water content.
Growth of most plants and survival of their roots normally
requires maintenance of adequate soil oxygen. This in turn
requires maintainance of soil water well below saturation, to
enable rapid gas diffusion in the soil.
Sumber: http://www.landfood.ubc.ca/soil200/components/air.htm
POROSITAS TANAH
Soil porosity (f) is the ratio of pore
volume (Vf) to total soil volume (Vt)
f = Vf / Vt
It is generally between 30-60%. Porosity
tells us nothing about the relative amounts
of large and small pores, and should be
interpreted with caution. Generally, high
porosity (e.g. 60%) is an indicator of lack
of compaction and good soil conditions.
Sumber: http://www.landfood.ubc.ca/soil200/components/air.htm
KOMPOSISI UDARA TANAH
The soil air contains a number of gases of which
nitrogen, oxygen, carbon dioxide and water vapour
are the most important.
Soil air constantly moves from the soil pores into
the atmosphere and from the atmosphere into the
pore space.
Soil air and atmospheric air differ in the
compositions. Soil air contains a much greater
proportion of carbon dioxide and a lesser amount
of oxygen than atmospheric air.
At the same time, soil air contains a far great
amount of water vapour than atmospheric air. The
amount of nitrogen in soil air is almost the same as
in the atmosphere.
Sumber:
http://www.agriinfo.in/?page=topic&superid=4&topicid=283
FAKTOR YANG MEMPENGARUHI
KOMPOSISI UDARA TANAH
SIFAT DAN KONDISI TANAH:
The quantity of oxygen in soil air is less than that in
atmospheric air.
The amount of oxygen also depends upon the soil depth.
The oxygen content of the air in lower layer is usually less
than that of the surface soil.
This is possibly due to more readily diffusion of the oxygen
from the atmosphere into the surface soil than in the subsoil.
Light texture soil or sandy soil contains much higher
percentage than heavy soil.
The concentration of CO2 is usually greater in subsoil
probably due to more sluggish aeration in lower layer than in
the surface soil.
Sumber:
http://www.agriinfo.in/?page=topic&superid=4&topicid=283
FAKTOR YANG MEMPENGARUHI
KOMPOSISI UDARA TANAH
JENIS TANAMAN:
Plant roots require oxygen, which they take from the soil air
and deplete the concentration of oxygen in the soil air. Soils
on which crops are grown contain more CO2 than fallow
lands.
The amount of CO2 is usually much greater near the roots of
plants than further away. It may be due to respiration by roots.
http://journeytoforever.org/farm
_library/howardAT/AT9b.html
Sumber:
http://www.agriinfo.in/?page=topic&superid=4&topicid=283
FAKTOR YANG MEMPENGARUHI KOMPOSISI
UDARA TANAH
AKTIVITAS MIKROBA TANAH:
The microorganisms in soil require oxygen for respiration and
they take it from the soil air and thus deplete its concentration
in the soil air.
Decomposition of organic matter produces CO2 because of
increased microbial activity. Hence, soils rich in organic
matter contain higher percentage of CO2.
http://www.extension.org/pages/18657/soilmicrobial-nitrogen-cycling-for-organic-farms
Sumber:
http://www.agriinfo.in/?page=topic&superid=4&topicid=283
FAKTOR YANG MEMPENGARUHI
KOMPOSISI UDARA TANAH
VARIASI MUSIMAN:
The quantity of oxygen is usually higher in dry
season than during the monsoon. Because soils are
normally drier during the summer months,
opportunity for gaseous exchange is greater during
this period. This results in relatively high O2 and
low CO2 levels.
Temperature also influences the CO2 content in the
soil air. High temperature during summer season
encourages microorganism activity which results in
higher production of CO2.
Sumber:
http://www.agriinfo.in/?page=topic&superid=4&topicid=283
GAS DALAM TANAH
The air space in soil contains oxygen to provide for respiration of
plant roots and soil organisms. This air space could also contain
carbon dioxide as a product of respiration of plant roots and soil
organisms.
KomposiSI UDARA dalam TANAH dan atmosphere:
Nitrogen: Soil Air: 79.2% Atmosphere: 79.0%
Oxygen: Soil Air: 20.6% Atmosphere: 20.9%
Carbon Dioxide: Soil Air: 0.25% Atmosphere: 0.03%
Gas molecules in soil are in continuous thermal motion according
to the kinetic theory of gases, there is also collision between
molecules - a random walk.
In soil, a concentration gradient causes net movement of
molecules from high concentration to low concentration, this
gives the movement of gas by diffusion.
Numerically, it is explained by Fick's law of diffusion.
Soil gas includes air, water vapour and the pollutants that might
be picked up from the soil underneath a building and carried by
air leakage into the building.
Sumber: Russell, E. J.; Appleyard, A. . (1915). "The Atmosphere of
the Soil: Its Composition and the Causes of Variation". The Journal of
Agricultural Science 7: 1.
OKSIGEN DALAM UDARA TANAH
Oxygen concentrations in the soil atmosphere greatly
influenced the growth and mineral uptake of
Eupatorium odoratum inoculated with Glomus
macrocarpus.
Shoot and root dry weights and length of mycorrhizal
plants increased with O2 concentration up to 16%.
Mycorrhizal plants at 21% O2 or non-aerated controls
were smaller than those at 12 and 16% O2. Nonmycorrhizal plants had lower shoot and root dry wts
than mycorrhizal plants at all O2 levels except at 0%.
Phosphorus concentration in mycorrhizal and nonmycorrhizal plants differed significantly but did not
increase with increasing O2. Mycorrhizal plants
contained higher quantities of N, K, Ca and Mg than
non-mycorrhizal and showed positive response in
nutrient uptake to increase in soil O2. Inoculation and
increased soil O2 resulted in higher concentrations of
K and Mg but not of N and Ca. The development of
Glomus macrocarpus exhibited quantitative and
qualitative response to different soil O2 levels.
New Phytologist > Vol. 88, No. 4, Aug., 1981 …. Diunduh
7/2/2012
AERASI TANAH - HASIL TANAMAN
Soil aeration is a property which relates to the
ability to provide air of suitable composition to
plant roots and to organisms growing in the soil.
Good aeration depends on adequate exchange of
air in the soil with air from the atmosphere. If a soil
is well-aerated, the composition of the soil air will
not be greatly different from that in the
atmosphere. If aeration is impeded, the soil air will
be higher in carbon dioxide and lower in oxygen
than the atmosphere above the soil.
Plant roots and soil organisms use oxygen and
release carbon dioxide so lack of free interchange
with the atmosphere may result in appreciably
altered composition of the soil air. Diffusion of air
through soils seems to be much more directly
dependent on the volume of air-filled pores than on
pore sizes.
…. Diunduh 7/2/2012
THE EFFECT OF SOIL WATER AND
AERATION ON SEED GERMINATION
S. DASBERG and K. MENDEL
The Volcani Institute of Agricultural Research
Bet Dagan, Israel
Received January 25, 1971.
The time rate of germination and the final germination
percentage of Oryzopsis holciformis decreased with
increasing water stress. The optimum matric potential
for germination was–0.005 bar in coarse sand and –0.5
bar in sandy loam soil. This discrepancy was explained
by changes in the rate of water-supply to the seed, as
determined by the area of contact between seed and
germination medium, and by the hydraulic conductivity
of the medium.
At high soil moisture potentials germination also
decreased. Such a decrease was not found at
equivalent osmotic potentials. It seems that this
decrease in germination was brought about by the
thickening of the water films around the seeds, which
interfered with oxygen diffusion. This assumption was
supported by determinations with Pt electrodes, and by
previous work on germination at lowered oxygen
concentrations.
J. Exp. Bot. (1971) 22 (4): 992-998.…. Diunduh 7/2/2012
ISHS Acta Horticulturae 563: International Conference on
Environmental Problems Associated with Nitrogen Fertilisation of
Field Grown Vegetable Crops
EFFECT OF SOIL AERATION ON NITROGEN AVAILABILITY
AND GROWTH OF SELECTED VEGETABLES-PRELIMINARY
RESULTS
H. Heuberger, J. Livet, W. Schnitzler
After heavy rainfall or irrigation, the macropores of the soil are
filled with water leading to limited gas diffusion and reduced
oxygen content of the soil air for a certain period of time. In this
situation, soil aeration by means of forced injection of
atmospheric air into the soil via a subsurface drip irrigation
system, is thought to accelerate the depletion of water from
macropores and increase the oxygen concentration in the soil air.
In 1999, cauliflower (Brassica oleracea L. convar. botrytis (L.)
Alef. var. botrytis L.), cv. 'Fargo' and sweet corn (Zea mays L.
convar. saccharata Koern.), cv. 'Tasty Sweet' were grown in a
silty clay loam under varying drip irrigation, fertigation, and
aeration conditions. The drip laterals for irrigation (S-I) and
fertigation (S-F) were placed 5 cm below the soil surface. In
another fertigation treatment (Sub-F) and for fertigation cum
aeration (Sub-F-A), the laterals were placed at 15 cm soil depth
(Subsurface). Nitrogen fertilisation was 250 kg N/ha for
cauliflower and 180 kg N/ha for sweet corn with basal
application and top dressing in S-I and fertigation after basal
application in the fertigated treatments.
compared to S-I (single-plot comparison).
…. Diunduh 7/2/2012
ISHS Acta Horticulturae 563: International Conference on
Environmental Problems Associated with Nitrogen Fertilisation
of Field Grown Vegetable Crops
EFFECT OF SOIL AERATION ON NITROGEN
AVAILABILITY AND GROWTH OF SELECTED
VEGETABLES-PRELIMINARY RESULTS
H. Heuberger, J. Livet, W. Schnitzler
Available N, which was defined as nitrate in the
rooting zone, did not differ between the three
fertigation treatments. Nitrate in the sap of
cauliflower petioles was determined from 7 weeks
after planting until harvest. It always showed
slightly but not significantly higher nitrate
concentrations in the aerated compared to the
non-aerated cauliflower. N uptake and total fresh
weight and product weight of cauliflower did not
differ among treatments.
In the sweet corn section of the experimental field,
a waterlogged area disturbed field uniformity but
revealed the positive effect of fertigation combined
with aeration by more vigorous corn crop and
higher cob yield compared to S-I (single-plot
comparison).
…. Diunduh 7/2/2012
REDOX POTENTIAL IN IRRIGATED DESERT SOILS AS
AN INDICATOR OF AERATION STATUS
B. D. Meek and L. B. Grass
The redox potential (Eh) of irrigated desert soils was
evaluated under a wide range of conditions. Factors
important in controlling Eh were temperature,
flooding time, soil water content, and energy source.
Field heterogeneity necessitated using 10 to 20
electrodes (placed in a 30-cm square) to characterize a
treatment. The Eh varied over a short distance with
variations not due to poisoning or erratic electrode
readings.
A 5C increase in temperature at the 15-cm depth
resulted in a 50-mV decrease in redox potential. The
length of soil saturation time correlated directly with
the decrease in Eh. When the soil was not saturated
during irrigation (sprinkler or drip), Eh decreased less
than when the soil was flooded. The amount of energy
available to microorganisms has a major effect on how
low the Eh decreased in a flooded soil.
SSSAJ. 1975 Vol. 39 No. 5, p. 870-875
…. Diunduh 7/2/2012
ISHS Acta Horticulturae 504: VI Symposium on Stand
Establishment and ISHS Seed Symposium
SOIL AERATION EFFECTS ON ROOT GROWTH AND
ACTIVITY
B. Huang, D. Scott NeSmith
Poor soil aeration or oxygen deficiency is a major factor limiting
seedling establishment. Oxygen deficiency in the soil can occur
because of improper soil management, such as over-irrigation
and soil compaction; poor soil quality, such as heavy finetextured soils or layered soils with inadequate drainage;
excessive rainfall or flooding; usage of excessively small
containers for transplant production.
Inferior stand establishment can occur due to the inhibitory
effects of low aeration on root elongation, proliferation, viability,
respiratory capacity, carbohydrate accumulation, hormone
synthesis, and water and nutrient uptake. Plants that are tolerant
to low soil aeration may develop morphological and anatomical
features in roots that facilitate oxygen utilization and plant
survival of low oxygen stress. These adaptive responses include
the formation of aerenchyma tissues in the root cortex,
development of adventitious roots near the soil surface, and
increases in root diameter.
…. Diunduh 7/2/2012
THE IMPACT OF SOIL COMPACTION ON SOIL
AERATION AND FINE ROOT DENSITY OF Quercus
palustris
G Watson, P Kelsey
Urban Forestry Urban Greening (2006)
Volume: 4, Issue: 2, Pages: 69-74
The soil around Quercus palustris trees, 30cm (11.8in) average
diameter breast height (DBH) were treated by compaction (C) or C plus
clay slurry (CS) treatments in November 1994 and repeated in May
1996. Soil oxygen diffusion rate (ODR), fine root density (FRD), DBH,
twig growth, leaf area and dieback were monitored for 4 years
beginning in 1996. Both compaction treatments significantly reduced
ODR at 15cm. Early each season, ODR was below the 0.20g/cm2/min
threshold level reported to inhibit root growth in several species Stolzy,
L.H., Letey, J., 1964. Correlation of plant response to soil oxygen
diffusion rates. Hilgardia 35, 567-576 for all treatments and depths. In
summer each year, ODR was adequate in the shallow soils of all
treatments, though often still significantly lower in compacted soils. At
30cm, there were no consistent differences in ODR between compacted
and uncompacted soil. Significant differences in FRD due to
compaction treatments were inconsistent and limited to the upper 9cm
of soil in years 2 and 3. Reduced FRD in compacted soils may be a
response to the reduced ODR in spring. There were no differences in
DBH, twig growth, leaf area or dieback rating. Given the minimal
difference in root growth, the lack of differences in top growth are
understandable. This controlled study, and others preceding it, have
failed to clearly show the underlying causes of tree decline and death
commonly associated with soil compaction and addition of fill soil in
real landscapes.
…. Diunduh 7/2/2012. http://www.mendeley.com/research/impact-soilcompaction-soil-aeration-fine-root-density-quercus-palustris/
Soil aeration for dairy manure spreading on forage: Effects
on ammonia volatilisation and yield
R. Gordon, G. Patterson, T. Harz, V. Rodd, J. MacLeod
Canadian Journal of Soil Science, 2000, 80:(2) 319-326, 10.4141/S99054
Experiments were conducted to evaluate the effects of
performing soil aeration either before or after spreading
liquid manure in forage production systems. The
experiments included eight trials performed in 1996 using a
non-interfering diffusion method to determine ammonia
(NH3) flux emissions from both aerated and control plots.
For all eight trials, the manure application rate was 75 355 L
ha−1.
The average NH3 loss for the aerated treatment was 67.3 kg
ha−1 while the loss for the control plots was 63.0 kg ha−1.
Although differences in the NH3 loss between treatments
were low, substantial variations were observed between
individual trials depending on the prevailing meteorological
conditions.To further evaluate the effects of soil aeration, 11
trials were carried out on Nova Scotia dairy farms in 1996
and 1997 to identify yield effects. Manure application rates
ranged from 18 000 to 64 000 L ha−1. The average forage
yield on aerated treatments was 9.4% below control
treatments (i.e., manure without aeration). Of the 11 trials, 9
resulted in significantly (P < 0.05) reduced yield with soil
aeration. Key words: Liquid manure, ammonia
volatilisation, soil aeration
Diunduh 7/2/2012. http://pubs.aic.ca/doi/abs/10.4141/S99-054
American Journal of Botany Vol. 66, No. 6, Jul., 1979.
The Effect of Aeration on the Growth of Spartina
alterniflora Loisel.(pp. 685-691)
Rick A. Linthurst
. A greenhouse experiment was designed to investigate the
correlations between waterlogging and aeration, and associated
changes in pH, redox potentials and sulfide concentrations, on
the growth of Spartina alterniflora Loisel. Elemental
concentrations of the aerial and root material were determined
and used for correlations with growth response. Redox
potentials adjusted to pH 7 (Eh 7) ranged from -184 mv to 5
mv and were highly correlated (r) with aerial and root dry
weight biomass (.97 and .97, respectively) and plant height
(1.0) The range of soil pH at the conclusion of the study was
6.07 to 6.74 and was negatively correlated with aerial and root
dry weight biomass. Sulfide concentrations ranged from 10-2
to 10-7 M and vorrelations with aerial and root dry weights and
height were -.85, -.85 and -87, respectively. High negative
correlations were found between sodium and sulfur
concentrations and S. alterniflora growth. Positive correlations
between potassium, phosphorus, manganese, zinc, copper, iron
and growth response were also observed. Correlations of
elemental concentrations of the plants with redox potentials
and/or pH suggest that these two physical variables may be
responsible in part for the regulation of S. alterniflora growth
in nature by regulating availability of nutritional elements.
http://www.jstor.org/pss/2442413…. Diunduh 7/2/2012
AERASI TANAH
The ventilation of soil – rate of gas
exchange
Aerasi tanah dipengaruhi oleh:
– Porositas tanah
– Kandungan lengas tanah
– Oxygen consumption by organisms
Saturated soil = anaerobic: O2 has low
solubility in H2O and slow rate of
dissolution
O2 present = aerobic (oxic);
O2 absent = anaerobic (red.)
…. Diunduh 7/2/2012
KOMPOSISI UDARA TANAH
Air above soil: 21% O2, 0.035% CO2, 78% N2
Soil atmosphere: inverse relationship between
O2 and CO2
O2 ~ 20% at surface to < 5% in lower horizons No
O2, anaerobic (typical of wet soils)
Carbon dioxide levels often 0.35 % – 10× that of air
Other gases:
H2O vapor (typically 100% relative humidity)
In strongly reduced soils: methane (CH4), ethylene
(C2H4), and hydrogen sulfide (H2S) (toxic to plants
if air exchange is too slow)
…. Diunduh 7/2/2012
Tendency of a substance to accept or donate electrons
Oxidation-reduction potential a way to characterize
aeration Eh
Redox potential
O2 readily accepts electrons from other elements;
it is an oxidizer
– ¼O2 + H+ + e– → ½H2O
Redox potential is dependent upon pH and
electron acceptors
Primary electron acceptors in soils (if O2 absent):
– ½NO3
– + H+ + e– → ½NO2– + ½H2O
– ½MnIVO2 + H+ + e– → ½Mn2+ + H2O
– Fe3+ + e– → Fe2+
– ½SO42– + 5H+ + 4e– → ½H2S + 2H2O
…. Diunduh 7/2/2012
FAKTOR YG MEMPENGARUHI REDOKS
Drainage of macropores and soil
macroporocity
Soil respiration rates (is there food
for bugs?)
Subsoil more depleted of O2 than
topsoil
Soil heterogeneity
– Profile
– Tillage
– Macroporocity
– Plant roots
…. Diunduh 7/2/2012
EFEK EKOLOGIS REDOKS
Breakdown of organic (crop, leaf litter, etc.)
residues: organic matter accumulates
in saturated soils → histic;
in aerated soils → CO2 + H2O
Absence of O2, anaerobes take over:
decomposition is slow and incomplete (partially
decomposed organic compounds produced)
How can you tell redox potential?
…. Diunduh 7/2/2012
POTENSIAL REDOKS DAPAT DILIHAT DARI
INDIKATOR:
Soil color (Fe & Mn transformations;
suboxic)
– Gray (gleyed)
– Mottles
– Matrix color
Gases (S & C transformations; anoxic)
– H2S (reduction of SO42–), mercaptans,
etc.
– Methane (reduction of CO2)
Vegetasi:
Toleransi tumbuhan terhadap aerasi buruk
sangat beragam
…. Diunduh 7/2/2012
WETLAND – LAHAN YANG AERASINYA
BURUK
Soils that are water-saturated near the surface for
prolonged periods when the soil temperature is high
enough to result in anaerobic conditions (bugs active
to deplete soil O2)
Swamps, bogs, coastal (salt-affected) marshes, etc.
Histosols & histic epipedons
Frozen soils (Histels)
A histosol is a soil consisting primarily of
organic materials. They are defined as having
40 centimetres (16 in) or more of organic soil
material in the upper 80 centimetres (31 in).
Organic soil material has an organic carbon
content (by weight) of 12 to 18 percent, or
more, depending on the clay content of the soil.
http://en.wikipedia.org/wiki/Histosol…. Diunduh 7/2/2012
WHAT IS A WETLAND?
“Wetlands are lands transitional between
terrestrial and aquatic systems where the water
table is usually at or near the surface or the
land is covered by shallow water.”
(Cowardin et al., 1985)
A wetland is an area of ground that is
saturated with water either permanently or
seasonally. Wetlands are categorized by their
characteristic vegetation, which is adapted
to these unique soil conditions.
The water found in wetlands can be
saltwater, freshwater, or brackish.
Wetlands include swamps, marshes, and
bogs, among others.
http://en.wikipedia.org/wiki/Wetland…. Diunduh 16/2/2012
TIGA CIRI WETLANDS
Wetlands vary widely due to local and regional
differences in topography, hydrology,
vegetation, and other factors, including human
disturbance. Wetlands can be divided into two
main classes: tidal and non-tidal areas.
Vegetation:
More than 50% of the dominant species are
hydrophytic plants (aerenchyma tissues typical)
Hydrology:
Seasonally inundated and/or saturated for
consecutive days > 12.5% of growing season
Hydric soils (redoximorphic features in upper
horizons):
Peraquic & aquic moisture regimes
Gley chroma (< 1)
Organic matter accumulation
http://en.wikipedia.org/wiki/Wetland…. Diunduh 16/2/2012
PENTINGNYA WETLANDS
Pengendalian Banjir:
Temporary storage of excess water
>19 million acres of wetlands have been drained in
the Upper Mississippi River Valley
Loss of 30 million acre-feet of storage
Restoration of 15% would have reduced flood stage
at St. Louis in 1993 by 2 feet
The wetland system of floodplains is formed from
major rivers downstream from their headwaters.
The floodplains of major rivers act as natural
storage reservoirs, enabling excess water to spread
out over a wide area, which reduces its depth and
speed.
Wetlands close to the headwaters of streams and
rivers can slow down rainwater runoff and spring
snowmelt so that it doesn’t run straight off the land
into water courses. This can help prevent sudden,
damaging floods downstream.
http://en.wikipedia.org/wiki/Wetland…. Diunduh 15/2/2012
PENTINGNYA WETLANDS
Kualiats Air
– Water movement VERY slow
– Sediments settle
– Nutrients utilized by plant life
– Effective pollution filter (agricultural and urban)
Groundwater recharge
Shoreline protection
Wetland systems are directly linked to groundwater and a crucial
regulator of both the quantity and quality of water found below
the ground. Wetland systems that are made of permeable
sediments like limestone or occur in areas with highly variable
and fluctuating water tables especially have a role in groundwater
replenishment or water recharge. Sediments that are porous allow
water to filter down through the soil and overlying rock into
aquifers which are the source of 95% of the world’s drinking
water.
Wetlands can also act as recharge areas when the surrounding
water table is low and as a discharge zone when it is too high.
Karst (cave) systems are a unique example of this system and are
a connection of underground rivers influenced by rain and other
forms of precipitation. These wetland systems are capable of
regulating changes in the water table on upwards of 130 meters
(426.5 feet).
http://en.wikipedia.org/wiki/Wetland…. Diunduh 15/2/2012
PENTINGNYA WETLANDS
Soil T-Affected Processes
• Plant growth rates
• Seed germination
• Root functions
• Microbial processes
– < 5 ºC not much happens
– Biological activity doubles with every 10 ºC increase
• Freezing and thawing
– Ice lenses
– Frost heaving
Wetlands cycle both sediments and nutrients balancing
terrestrial and aquatic ecosystems. A natural function of
wetland vegetation is the up-take and storage of nutrients
found in the surrounding soil and water. These nutrients are
retained in the system until the plant dies or is harvested by
animals or humans. Wetland vegetation productivity is
linked to the climate, wetland type, and nutrient availability.
The grasses of fertile floodplains produce the highest yield
including plants such as Arundo donax(giant reed), Cyperus
papyrus (papyrus), Phragmites (reed) and Typha (cattail,
bulrush).
http://en.wikipedia.org/wiki/Wetland…. Diunduh 16/2/2012
PENYERAPAN DAN KEHILANGAN ENERGI
SURYA
• Albedo: the fraction of incident radiation that is
reflected from the land surface
• Aspect: how the land faces the sun – south
facing vs. north facing
• Rain:
– Summer rains cool the soil
– Spring rains warm the surface but,
overall, make the soil cooler and harder to warm
(high specific heat of water determines the rate at
which soil warms in the spring).
…. Diunduh 7/2/2012
AERASI TANAH
Ventilation of soil allowing gases to be exchanged
with atmosphere
Proses pertukaran ags terjadi melalui:
Mass flow: air forced in by wind or pressure
Diffusion: gas moves back and forth from soil
to atmosphere acc. to pressure
http://www.sciencedirect.com/science/article/pii/S0048969799000157
…. Diunduh 7/2/2012
Oksidasi
Loss of electrons
Fe+2
Fe+3
-26
e-
+28
Fe+2
…. Diunduh 7/2/2012
-25
+28
Fe+3
REDUKSI
Gain of electrons
Fe+3
Fe+2
-26
e-
+28
-25
+28
Fe+2
Fe+3
…. Diunduh 7/2/2012
Bentuk-bentuk oksidator-reduktor
Iron
Fe+2 (ferrous)
Fe+3 (ferric)
Nitrogen N+3 in NH+4 (ammonium)
N+5 in NO3- (nitrate)
Manganese Mn+2 (manganous)
Mn+4 (manganic)
http://www.meta-synthesis.com/webbook/15_redox/redox.php
…. Diunduh 7/2/2012
Bentuk-bentuk oksidasi dan reduksi
Sulfur S-2 (sulfide) …. Red
SO4-2 (sulfate) ….. Oks
Carbon CH4 (methane) …. Red
CO2 …….Oks
http://www.biology.ufl.edu/permafrostcarbon/anaerobic_aerobic.html
…. Diunduh 14/2/2012
REAKSI OKSIDASI-REDUKSI
Oxidation reduction reactions (redox for short) are the core of energy
supply in batteries. In short, when a battery is supplying energy, redox
reactions are occurring that are converting chemical energy into
electrical energy. Chemical energy refers to energy stored in the bonds
between atoms. Some bonds require more energy to form than others.
When these high energy bonds break and new lower energy molecules
are formed in a redox reaction, the energy difference is released.
Batteries operate by harnessing that released energy and using it to drive
electrical devices.
http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookenzym.htm
l …. Diunduh 14/2/2012
REAKSI OKSIDASI
electrons that could potentially be transferred to others
2FeO + 2H2O
Fe+2
2FeOOH + 2H+ + 2 eFe+3
H+ ions formed
http://www.ru.nl/tracegasfacility/life_science_trace/plant_physiology/m
ethane_oxidation/ …. Diunduh 14/2/2012
RESPIRASI AEROBIK
Oxygen is electron acceptor for organic carbon,
to release energy.
As oxygen oxidizes carbon, oxygen in turn is
reduced (H2O)
O2 + C6H12O6
Electron
acceptor
CO2 + H2O
Electron
donor
…. Diunduh 14/2/2012
To determine Eh
Insert electrode in soil solution:
– free dissolved oxygen present : Eh stays same
– oxygen disappears, reduction (electron gain)
takes place and probe measures degree of
reduction ( mv)
– As organic substances are oxidized (in
respiration) Eh drops as sequence of reductions
(electron gains) takes place.
http://www.soils.wisc.edu/courses/SS325/oxides.htm …. Diunduh
14/2/2012
Bentuk-bentuk oksidasi dan reduksi hara
Oxidized form
Reduced form
Eh (v)
O2
H2O
.38 - .32
NO3-1
N2
.28 - .22
Mn+4
Mn+2
.22 - .18
Fe+3
Fe+2
.11 - .08
SO4-2
S-2
-.14 - -.17
CO2
CH4
-.2 - -.28
http://edafologia.ugr.es/hidro/conceptw.htm …. Diunduh 14/2/2012
Organic substrate oxidized (decomposed) by
various electron acceptors:
O2
NO3Mn+4
Fe+3
SO4-2
Rates of decomposition are most rapid in
presence of oxygen
http://wvlc.uwaterloo.ca/biology447/modules/module8/soil/chap2d.htm
…. Diunduh 14/2/2012
AERASI TANAH - MIKROBA DEKOMPOSER
Poor aeration slows decay
– Anaerobic organisms
Poorly aerated soils may contain toxic, not oxidized
products of decomposition: alcohols, organic acids
Organic matter accumulates
– Allows Histosol development
Organic Matter Decomposition and the Formation of Humic Substances.
http://www.agnet.org/library.php?func=view&id=20110913155219&typ
e_id=2 …. Diunduh 7/2/2012
AERASI TANAH - BENTUK DAN
MOBILITAS HARA
Soil aeration determines which forms of
chemicals are present and how mobile
they are

Redox colors in Poorly and Well-Aerated Soil
 Nutrient elements
Anaerobic digestion, which takes place in three stages inside an airtight
container, produces biogas. Different kinds of micro-organisms are
responsible for the processes that characterize each stage.
http://www.daviddarling.info/encyclopedia/A/AE_anaerobic_digestion.h
tml …. Diunduh 7/2/2012
BENTUK SENYAWA / ION :
TANAH AERASI JELEK
Reduced forms of iron and manganese
Fe+2, Mn+2
Reduced iron is soluble; moves through soil, removing red,
leaving gray, low chroma colors (redox depletions)
Reduced manganese : hard black concretions
http://www.wtert.eu/default.asp?Menue=13&ShowDok=12 …. Diunduh
7/2/2012
AERASI TANAH - PENYIANGAN
Penyiangan bertujuan untuk membuang semua jenis
tumbuhan pengganggu yang hidup di sekitar
tanaman murbei. Gulma tidak saja menurunkan
kesuburan tanah dengan mengisap hara, akan tetapi
dapat juga sebagai sumber bersarangnya hama dan
penyakit. Tindakan pemeliharaan yang satu ini
paling sering dilakukan sebagai kegiatan
pemeliharaan rutin. Penyiangan dapat dilakukan
dengan efektif bila dilaksanakan sedini mungkin
pada waktu gulma mulai tumbuh. Rumput-rumput
yang tumbuh disiang dengan menggunakan alat
sabit atau cungkir, kemudian hasil siangan dikubur.
Pendangiran adalah kegiatan penggemburan
tanah. Dengan tujuan supaya membuat tanah
menjadi lunak dan memperbaiki aerasi
tanah. Dengan demikian kehidupan mikro
organisme dapat dirangsang dan mempercepat
pelapukan bahan organik di dalam tanah.
http://www.agrisilk.com/Budidaya/murbei/Pemupukan.html ….
Diunduh 14/2/2012
Organic Matter Decomposition Pathways for
Anaerobic Respiration.
http://www.agnet.org/library.php?func=view&id=20110913155219&typ
e_id=2 …. Diunduh 7/2/2012
Organic Matter Decomposition Pathways for
Aerobic Respiration.
http://www.agnet.org/library.php?func=view&id=20110913155219&typ
e_id=2 …. Diunduh 7/2/2012
AERASI TANAH
Soil aeration is one of the most important factors affecting
turf health. Poor aeration can lead to root death. The
black layer often found in putting greens is due to poor
aeration.
Aerasi tanah dapat diperbaiki dengan jalan memperbaiki
struktur tanah dan pengolahan tanah.
Aerasi tanah merupakan proses dimana udara di
dalam tanah digantikan oleh udara dari atmosfer.
Dalam tanah yang aerasinya baik, udara tanah
mempunyai komposisi yang sama dengan
atmosfer di atasnya.
Tanah- tanah beraerasi buruk biasanya
mengandung persentase CO2 yang lebih banyak
dan tentunya persentase O2 yang lebih sedikit
daripada atmosfer di atasnya.
Tingkat aerasi sebagian besar bergantung-kepada
volume dan kontinuitas pori-pori terisi udara di
dalam tanah.
http://ilmutanah.unpad.ac.id/glossary/Glossary-1/A/Aerasi-tanah-7/ ….
Diunduh 12/2/2012
PEMADATAN TANAH
Soil compaction occurs when forces, such as tire or foot
traffic, compress the soil and alter pore structure.
Bulk density increases, macropores decrease, infiltration
decreases, aeration decreases.
Compaction is most a problem when soils are wet. A
similar problem is caused by shearing forces or puddling
of soil surfaces.
Pemadatan tanah adalah proses naiknya kerapatan tanah
dengan memperkecil jarak antar partikel sehingga terjadi
reduksi volume udara : tidak terjadi perubahan volume air
yang cukup berarti pada tanah tersebut.
Tingkat pemadatan diukur dari berat volume kering yang
dipadatkan. Bila air ditambahkan pada suatu tanah yang
sedang dipadatkan, air tersebut akan berfungsi sebagai unsur
pembasah atau pelumas pada partikel – partikel tanah. Karena
adanya air, partikel – partikel tersebut akan lebih mudah
bergerak dan bergeseran satu sama lain dan membentuk
kedudukan yang lebih rapat/padat. Untuk usaha pemadatan
yang sama, berat volume kering dari tanah akan naik bila
kadar air dalam tanah (pada saat dipadatkan) meningkat.
http://yogoz.wordpress.com/2011/01/31/pemadatan-tanah-2/ ….
Diunduh 12/2/2012
PEMADATAN TANAH
• Soil compaction is controlled by
restricting traffic, modifying soils,
and cultivation.
• Soils can be modified to resist
compaction, but it’s not as simple as
it sounds. The old dogma about
adding a little sand to lighten a
heavy soil is just plain wrong. But
pure sands are great for resisting
compaction.
• Cultivation is practiced in many
forms.
…. Diunduh 12/2/2012
PENDANGIRAN TANAH
Cultivation before planting is pretty easy, as long
as the soil is not too wet.
Cultivation after planting is the basis of an entire
equipment industry.
Pieces include hollow and solid tine aerifiers,
water injectors, air injectors, slicers, spikers,
wing blades, and Klingon disruptor beams.
Pemeliharaan tanaman menggunakan alsintan
atau kultivasi bertujuan menyiapkan kondisi
tanah agar memungkinkan terjadinya
perkembangan akar yang baik dan mendukung
pertumbuhan tanaman. Namun juga disadari
bahwa kultivasi yang kurang tepat dapat
mengakibatkan dampak negatif terhadap sifat
fisik tanah, yaitu terjadi pemam-patan tanah,
dan tingginya biaya produksi.
http://www.gunungmadu.co.id/index.php?modul=artikel&id=utama&ko
debrt=kultivasi&colvis=false …. Diunduh 12/2/2012
I. Process of Soil Aeration
A. O2 availability in field
1. soil macroporosity
(texture/structure)
2. soil water content (proportion of
porosity filled with air)
3. O2 consumption by respiring
organisms (plant roots and
microbes)
B. Excess Moisture
1. water saturated/waterlogged:
condition when all or nearly all of
the soil pores are filled with H2O
2. adaption
C. Gas exchange
1. mass flow
2. diffusion (Fig. 7.3)
PROSES DIFUSI GAS
Dynamic observations were carried out on arable grey
forest soil under barley. Fifteen parameters were
determined continuously for 44 days: gas composition of
soil air with membrane probes, plant photosynthetic
activity and dark respiration separately for soil and plants
by the chamber method, microbial biomass by kinetic
method, number of protozoa by direct microscopy, standing
crop of the above- and belowground phytomasses, content
of soluble organic matter in soil, moisture and temperature
of soil, insolation and precipitation.
All dynamic variables, which are related to gas exchange
and microbial activity, were found to oscillate with the
period of 2-5 days. The dynamic pattern of gas exchange
was controlled by some components of sun radiation via
plant photosynthetic activity.
http://www.jstor.org/pss/20113105…. Diunduh 12/2/2012
AERASI TANAH
A. Composition
1. O2
2. CO2 (Fig. 7.8)
3. other gases
B. Air-filled porosity
1. ideal composition
2. O2 diffusion through
water<<<<<air
C. Chemical redox potential
1. redox rxns
2. role of O2
3. other e- acceptors (Table 7.1)
KONSENTRASI CO2 DALAM
UDARA TANAH
…. Diunduh 12/2/2012
Other e- acceptors
FAKTOR AERASI TANAH
A. Drainage
B. Rates of respiration
C. Subsoil vs. topsoil
D. Soil heterogeneity
E. Seasonal differences
F. Effects of vegetation
…. Diunduh 12/2/2012
FAKTOR AERASI TANAH
A. Drainage
1. Why are macropores important to soil
aeration?
B. Rates of respiration
2. What management activities can alter
soil air composition?
C. Subsoil vs. topsoil
3. Why do subsoils have lower O2
concentrations than surface soils?
D. Soil heterogeneity
4. How do O2 and CO2 concentrations
change within a profile?
5. What effect does tillage have on
aeration?
E. Seasonal differences
6. Contrast spring vs. summer soil aeration.
F. Effects of vegetation
7. What is an effect of one specific type of
vegetation on soil aeration?
UDARA
TANAH