UDARA TANAH &
AERASI
diabstraksikan Oleh: Smno.jursntnh.fpub.Febr2013
Foto: smno.kampus.ub.febr2013
UDARA TANAH
…. Diunduh 14/2/2012
Udara yang berada dalam ruang pori‐poritanah (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 haraN2 : 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/soil-air#ixzz1mP6ZjavG
KEPEKAAN TANAMAN
…. Diunduh 7/2/2012
Kepekaan tanaman terhadap O2 tanah/aerasi :
Tanaman yg sangat peka thdp O2tanah/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#ixzz1mP6xpcrT
AERASI TANAH
…. Diunduh 7/2/2012
Pengharkatan kondisi aerasi :
Porositas total : jumlah total pori tanah ( ygterisi udara & air) dinyatakan dlm % volume
tanah (jmlh pori mikro & makro)Volume total tanah :
Vs + Va + Vw = 11 – 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_important_for_air_to_get_into_soil#ixzz1mP7KzWEA
KAPASITAS UDARA EFEKTIF
…. Diunduh 14/2/2012
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 tanahPermukaan air tanah (GROUNDWATER)
Soil PoreFor 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#ixz
z1mP7erq1X
KAPASITAS AERASI TANAH
http://www.landfood.ubc.ca/soil200/components/air.htm…. Diunduh 7/2/2012
Kapasitas aerasi/porositas aerasi/porositas non kapiler :
yaitu kapasitas udara pada saatlengas 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.
FAKTOR KOMPOSISI UDARA TANAH
http://www.landfood.ubc.ca/soil200/components/air.htm…. Diunduh 7/2/2012
Faktor‐faktor yang mempengaruhi komposisiudara tanah :
IklimSifat tanah seperti tekstur, struktur, tinggi permukaan
air tanahSifat tanaman
Keterdapatan tanaman mengurangi kadar O2dan 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.
…. Diunduh 7/2/2012
KOMPOSISI UDARA TANAH
Tergantung dari proses biologi serta sukar mudahnya tukar menukar dengan udara
atmosferContoh udara tanah sawah yang bebas air
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
Secara riil komposisi udara tanah dibandingudara atmosfer, sebagai berikut
PERTUKARAN UDARA
http://www.landfood.ubc.ca/soil200/components/air.htm…. Diunduh 7/2/2012
Komposisi tersebut selalu berubah‐ubah tergantung beberapa faktor yaitu :
Kecepatan pertukaran udara tanah danatmosfer, tergantung :o Tanah : tekstur, struktur, B.O, KL, suhuo Iklim : angin, tekanan udara, & suhuo 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.
Pertukaran Udara Tanah/PembaruanKomposisi Udara Tanah
http://www.landfood.ubc.ca/soil200/components/air.htm…. Diunduh 7/2/2012
Pertukaran udara tanah & udara atmosfer dapat terjadi karena adanya gerakan udara.
Ada 3 faktor yg mempengaruhi pembaruanudara dalam tanah; yaitu :
Proses difusiAliran masa gasAir 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/dXwhere 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).
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
http://www.hissan.co.jp/business/moda/e_index.html …. Diunduh 14/2/2012
Aliran Massa Gasterjadi karena perbedaan tekanan total
udara dalam tanah dan udara atmosfer, hal initerjadi kalau :
Suhu tanah berubah Lengas tanah Kecepatan angin di atas tanah berubah
AIR HUJAN
…. Diunduh 14/2/2012
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)
Air hujan menggenang di jalan raya
…. Diunduh 14/2/2012
PENGARUH AERASI (TATA UDARA) DALAM TANAH
Perbaikan aerasi tanah akan berpengaruh terhadap :
Peningkatan kegiatan M.OPeningkatan penguraian B.OPeningkatan strukturisasiPencegahan terbentuknya senyawa TOKSIK :
Methan AmoniaH2S N2Nitrit Senyawa‐senyawa ferro
PENGELOLAAN UDARA TANAH
http://www.uraniumresources.com/isr-technology/photo-gallery …. Diunduh 14/2/2012
Pengelolaan udara tanah ditujukan untukmempercepat proses difusi dan aliran
massa gas, dengan usaha :
Perbaikan struktur tanahPengendalian lengas tanah
UDARA TANAH - PENGELOLAAN
http://www.extension.org/pages/18634/use-of-tillage-in-organic-farming-systems:-the-basics …. Diunduh 14/2/2012
Tindakan‐tindakan yang dapat dilakukan :Menghindari terbentuknya lapisan cadasserta pemampatan tanahPengolahan tanah yang tepatPenambahan B.O. ke dalam tanahPemberian mulsaPerbaikan drainase.
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 air2. 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
Air Tanah yang berlebihan1. Tanah jenuh air, tanah tergenang dapat
berpengaruh buruk pd tanaman pd umumnya2. Biasanya pd tanah-tanah yg drainasenya buruk dan
tekstur halus3. 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
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.
LAJU DIFUSI
OKSIGEN (LDO)
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
LDO adalah laju pergantian oksigen dalam tanah yg dipakai oleh akar tanaman yg bernafas atau digantikan oleh air.
SUSUNAN UDARA TANAH
% volume:Tempat O2 CO2
N2
Udara tanah:New York 15.10 4.50
81.40Inggris 20.65 0.25
79.20
Udara AtmosferInggris 20.97
79.00
Sumber: Lyon, Buckman & Brady, 1952.
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
Faktor Susunan Udara Tanah
Tanah lapisan atas vs Tanah lapisan bawahJumlah total ruangan pori tanah lapisan bawah lebih
sedikit dibanding tanah lapisan atas
% CO2 udara tanah Kedalaman sampling, cm0.5 gandum + rabuk 30
tanah bera + rabuk kandang Lempung liat berdebu
Lempung berdebu
tanah bera
180 Waktu sampling 10 20 % O2 udra
tnh
Susunan udara tanah tgt pada: 1. Jumlah ruangan / pori yg
tersedia2. Kecepatan reaksi biokimia3. Pertukaran gas
Penambahan bahan organik akan mengubah susunan udara tanah
AERASI &KEGIATA
N BIOLOGIS
Aerasi b uruk mempengaruhi Tanaman:1. Pertumbuhan perakaran sangat terbatas2. Penyerapan hara terhambat3. Air menjadi berkurang4. Pembentukan senyawa anorganik yang bersifat
toksik
Jasad Mikro1. Aerasi buruk menurunkan oksidasi bahan
organik tanah2. Penurunan ini lebih disebabkan oleh
kekurangan O23. Populasi jasad renik sangat terpengaruhi
olh aerasi4. Aerasi buruk mendorong aktifitas jasad
anaerob dan fakultatif, menghasilkan senyawa reduksi, fero, mangano, sulfida
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 Tekstur LDO pada kedalaman: Kondisi10 cm 20 cm 30 cm pertumbuhan
tanaman
Brokoli Lempung 53 31 38 Sangat baikSelada Lempung berdebu 49 26 32 BaikPhaseolus sp Lempung 27 27 25 Klorosis
Arbei Lempung berpasir 36 32 34 KlorosisKapas Lemping berliat 7 9 - KlorosisJeruk Lempung berpasir 64 45 39 Pertumbuhan
akarcepat
Sumber: Stolzy dan Letey, 1964.
Dekomposisi anaerobik
C6H12O6 3CO2 + 3 CH4 gula metan
Kondisi aerasi tanah berpengaruh terhadap bentuk unsur hara penting:
Unsur Kondisi Oksidasi Kondisi reduksi (tergenang)
Karbon CO2 CH4Nitrogen NO3- N2, NH4+Belerang SO4= H2S, S=
AERASI &KEGIATAN Pengelolaan
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 baik-buruknya aerasi tanah
Tindakan untuk memperbaiki aerasi ntanah:
1. Menghilangkan air yang berlebihan (drainase)
2. Memperbaiki agregasi dan pengolahan tanah
SUHU TANAH
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
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
Sumber: http://www.geo4va.vt.edu/A1/A1.htm
Amplitude of seasonal soil temperature change as a function of depth below
ground surface.
SERAPAN &
KEHILANGAN PANAS
Kehilangan panas dari tanah ke atmosfer, melalui KONDUKSI dan RADIASIRadiasi ini berupa infra merah, tidak terlihat mata, gelombang gelapRadiasi gelombang gelap ini berenergi tinggi dan selama pemancarannya
banyak panas yg hilang dari tanah
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 energi2. Lereng: 3. Tanaman penutup tanah: Hutan vs. tanah gundul
Tanah gundul lebih cepat memanas dan mendingin
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 AdmittanceSource: Lesley Dampier
PANAS JENIS
TANAH
Thermal Conductivity (λ): Measure of the ease with which a soil transmits heat. It describes heat flow in response to a temperature gradient..
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 = 0.20Kadar air 20% : PJ = 0.33Kadar air 30% : PJ = 0.38
Thermal ConductivitySource: Lesley
Dampier
PANAS PENGUAP
AN
Warna tanah vs. SuhuTanah gelap biasanya kaya bahan organik dan
kandungan airnya tinggi.Tanah gelap yg drainasenya buruk lambat memanas.
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.
Soil Heat Capacity (Cv): Amount of heat needed to cause a 1oC change in temperature of a unit volume of soil.
Heat CapacitySource: Lesley
Dampier
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
GERAKAN PANAS
DALAM TANAH
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
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
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 CapacitySource: Lesley
Dampier
SUHU TANAH
Suhu tanah. oC 15 20 25 30 35
Soildepth
cm 60
Januari Juli
300 Sumber: Fluker, 1956 (Texas)
Suha tanah pada suatu saat tergantung pada nisbah energi panas yang diserap dan yang hilang
Suhu tanah juga tergantung kedalaman tanah
Pengendalian Suhu Tanah
SuhuoC Kedalaman tanah 1.5 cm Kedalaman
tanah 15 cm 38
tanpa mulsa
Dengan mulsaTanpa
mulsa
Dengan mulsa
pagi sore pagi sore
Penggunaan mulsa organik mengakibatkan suhu tanah lebih rendah dan lebih merata
Pengelolaan air tanah secara tepat juga akan mempengaruhi suhu tanah
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-soil-health/
Lawn Aeration for a Greener, Thicker, Healthier Lawn!
Umber: http://yardplug.com/FAQ/FAQ1.htm
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.
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
Sumber; http://faculty.plattsburgh.edu/robert.fuller/370%20Files/Weeks13Soil%20Air%20&%20Temp/aastart14.htm
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
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 ; ug O2/cm2.minute
Sumber; http://faculty.plattsburgh.edu/robert.fuller/370%20Files/Weeks13Soil%20Air%20&%20Temp/aastart14.htm
Faktor-faktor yang mempengaruhi Aerasi
Sumber; http://faculty.plattsburgh.edu/robert.fuller/370%20Files/Weeks13Soil%20Air%20&%20Temp/aastart14.htm
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)
POTENSIAL REDOKS (Eh)
Sumber; http://faculty.plattsburgh.edu/robert.fuller/370%20Files/Weeks13Soil%20Air%20&%20Temp/aastart14.htm
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.
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).
SUMBER: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPLANTHOR
M.html
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.
TEKSTUR TANAH: THE KEY TO MANAGEMENT OF SOIL – PLANT – WATER
RELATIONSHIP
.SUMBER: http://www.ecoconsulting.com/balance.htm
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.
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. An increase in soil water content often causes a reduction in soil aeration.
2. Likewise, reducing soil water content may mean an increase in soil aeration.
3. 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 TANAHThe 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-is-soil.htm
SIFAT OLAH TANAH
Sumber: http://rbmc.com.au/aerway.htm
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.
PORI DAN UDARA TANAH
Sumber: http://www.landfood.ubc.ca/soil2
00/components/air.htm
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 air2. Movement of gasses within soil
3. Soil porosity
Sumber: http://www.landfood.ubc.ca/soil2
00/interaction/water_air.htm
Source: Lesley Dampier
KOMPOSISI UDARA TANAH
Sumber: http://www.landfood.ubc.ca/soil200/components/air.htm
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.
PERGERAKAN GAS DALAM TANAH
Sumber: http://www.landfood.ubc.ca/soil200/components/air.htm
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.
PERGERAKAN GAS DALAM TANAH
Sumber: http://www.landfood.ubc.ca/soil200/components/air.htm
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).
PERGERAKAN GAS DALAM TANAH
Sumber: http://www.landfood.ubc.ca/soil200/components/air.htm
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.
POROSITAS TANAH
Sumber: http://www.landfood.ubc.ca/soil200/components/air.htm
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.
KOMPOSISI UDARA TANAH
Sumber: http://www.agriinfo.in/?page=topic&superid=4&topicid=283
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.
FAKTOR YANG MEMPENGARUHI KOMPOSISI UDARA TANAH
Sumber: http://www.agriinfo.in/?page=topic&superid=4&topicid=283
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.
FAKTOR YANG MEMPENGARUHI KOMPOSISI UDARA TANAH
Sumber: http://www.agriinfo.in/?page=topic&superid=4&topicid=283
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
FAKTOR YANG MEMPENGARUHI KOMPOSISI UDARA TANAH
Sumber: http://www.agriinfo.in/?page=topic&superid=4&topicid=283
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/soil-microbial-nitrogen-cycling-for-organic-farms
FAKTOR YANG MEMPENGARUHI KOMPOSISI UDARA TANAH
Sumber: http://www.agriinfo.in/?page=topic&superid=4&topicid=283
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.
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.
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. Non-
mycorrhizal plants had lower shoot and root dry wts than mycorrhizal plants at all O2 levels except at 0%.
Phosphorus concentration in mycorrhizal and non-mycorrhizal 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
OKSIGEN DALAM UDARA TANAH
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. MENDELThe 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
RESULTSH. 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
…. Diunduh 7/2/2012
ISHS Acta Horticulturae 504: VI Symposium on Stand Establishment and ISHS Seed Symposium
SOIL AERATION EFFECTS ON ROOT GROWTH AND
ACTIVITYB. 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 fine-textured 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.
THE IMPACT OF SOIL COMPACTION ON SOIL AERATION AND FINE ROOT DENSITY OF Quercus
palustrisG Watson, P Kelsey
Urban Forestry Urban Greening (2006) Volume: 4, Issue: 2, Pages: 69-74
…. Diunduh 7/2/2012. http://www.mendeley.com/research/impact-soil-compaction-soil-aeration-fine-root-density-quercus-palustris/
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.
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/S99-
054
Diunduh 7/2/2012. http://pubs.aic.ca/doi/abs/10.4141/S99-054
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
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
http://www.jstor.org/pss/2442413…. Diunduh 7/2/2012
. 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.
AERASI TANAH
…. Diunduh 7/2/2012
The ventilation of soil – rate of gasexchange
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.)
KOMPOSISI UDARA TANAH
…. Diunduh 7/2/2012
Air above soil: 21% O2, 0.035% CO2, 78% N2
Soil atmosphere: inverse relationship betweenO2 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)
Tendency of a substance to accept or donate electronsOxidation-reduction potential a way to characterize
aeration Eh
…. Diunduh 7/2/2012
Redox potential
O2 readily accepts electrons from other elements;it is an oxidizer– ¼O2 + H+ + e– → ½H2O
Redox potential is dependent upon pH andelectron 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
FAKTOR YG MEMPENGARUHI REDOKS
…. Diunduh 7/2/2012
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
EFEK EKOLOGIS REDOKS
…. Diunduh 7/2/2012
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?
POTENSIAL REDOKS DAPAT DILIHAT DARI INDIKATOR:
…. Diunduh 7/2/2012
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
WETLAND – LAHAN YANG AERASINYA BURUK
http://en.wikipedia.org/wiki/Histosol…. Diunduh 7/2/2012
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/Wetland…. Diunduh 16/2/2012
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.
TIGA CIRI WETLANDS
http://en.wikipedia.org/wiki/Wetland…. Diunduh 16/2/2012
Vegetation:More than 50% of the dominant species arehydrophytic plants (aerenchyma tissues typical)
Hydrology:Seasonally inundated and/or saturated forconsecutive days > 12.5% of growing season
Hydric soils (redoximorphic features in upperhorizons):
Peraquic & aquic moisture regimesGley chroma (< 1)Organic matter accumulation
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.
PENTINGNYA WETLANDS
http://en.wikipedia.org/wiki/Wetland…. Diunduh 15/2/2012
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 storageRestoration 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
Kualiats Air– Water movement VERY slow– Sediments settle– Nutrients utilized by plant life
– Effective pollution filter (agricultural and urban)Groundwater rechargeShoreline protection
PENTINGNYA WETLANDS
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 16/2/2012
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
PENTINGNYA WETLANDS
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).
PENYERAPAN DAN KEHILANGAN ENERGI SURYA
…. Diunduh 7/2/2012
• Albedo: the fraction of incident radiation that isreflected from the land surface
• Aspect: how the land faces the sun – southfacing 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).
AERASI TANAH
http://www.sciencedirect.com/science/article/pii/S0048969799000157 …. Diunduh 7/2/2012
Ventilation of soil allowing gases to be exchanged with atmosphereProses 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
…. Diunduh 7/2/2012
Oksidasi
Loss of electronsFe+2 Fe+3
+28
-25
Fe+3
+28
-26
Fe+2
e-
…. Diunduh 7/2/2012
REDUKSI
Gain of electronsFe+3 Fe+2
+28
-25
Fe+3
+28
-26
Fe+2
e-
http://www.meta-synthesis.com/webbook/15_redox/redox.php …. 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)
Bentuk-bentuk oksidasi dan reduksi
http://www.biology.ufl.edu/permafrostcarbon/anaerobic_aerobic.html …. Diunduh 14/2/2012
Sulfur S-2 (sulfide) …. Red SO4
-2 (sulfate) ….. OksCarbon CH4 (methane) …. Red CO2 …….Oks
http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookenzym.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.ru.nl/tracegasfacility/life_science_trace/plant_physiology/methane_oxidation/ …. Diunduh 14/2/2012
REAKSI OKSIDASIelectrons that could potentially be transferred to others
2FeO + 2H2O 2FeOOH + 2H+ + 2 e-
Fe+2 Fe+3
H+ ions formed
…. 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 CO2 + H2O
Electron donorElectron
acceptor
http://www.soils.wisc.edu/courses/SS325/oxides.htm …. 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.
Bentuk-bentuk oksidasi dan reduksi hara
http://edafologia.ugr.es/hidro/conceptw.htm …. Diunduh 14/2/2012
Oxidized form Reduced form Eh (v)O2 H2O .38 - .32
NO3-1 N2 .28 - .22
Mn+4 Mn+2 .22 - .18Fe+3 Fe+2 .11 - .08SO4
-2 S-2 -.14 - -.17CO2 CH4 -.2 - -.28
http://wvlc.uwaterloo.ca/biology447/modules/module8/soil/chap2d.htm …. Diunduh 14/2/2012
Organic substrate oxidized (decomposed) by various electron acceptors:
O2
NO3-
Mn+4
Fe+3
SO4-2
Rates of decomposition are most rapid in presence of
oxygen
Organic Matter Decomposition and the Formation of Humic Substances. http://www.agnet.org/library.php?
func=view&id=20110913155219&type_id=2 …. Diunduh 7/2/2012
AERASI TANAH - MIKROBA DEKOMPOSER
Poor aeration slows decay– Anaerobic organisms
Poorly aerated soils may contain toxic, not oxidized products of decomposition: alcohols, organic acidsOrganic matter accumulates
– Allows Histosol development
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
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
http://www.wtert.eu/default.asp?Menue=13&ShowDok=12 …. Diunduh 7/2/2012
BENTUK SENYAWA / ION : TANAH AERASI JELEK
Reduced forms of iron and manganeseFe+2, Mn+2
Reduced iron is soluble; moves through soil, removing red, leaving gray, low
chroma colors (redox depletions)Reduced manganese : hard black
concretions
AERASI TANAH - PENYIANGAN
http://www.agrisilk.com/Budidaya/murbei/Pemupukan.html …. Diunduh 14/2/2012
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.
Organic Matter Decomposition Pathways for Anaerobic Respiration.
http://www.agnet.org/library.php?func=view&id=20110913155219&type_id=2 …. Diunduh 7/2/2012
http://www.agnet.org/library.php?func=view&id=20110913155219&type_id=2 …. Diunduh 7/2/2012
Organic Matter Decomposition Pathways for Aerobic Respiration.
AERASI TANAHSoil 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 TANAHSoil 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.
http://yogoz.wordpress.com/2011/01/31/pemadatan-tanah-2/ …. Diunduh 12/2/2012
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.
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 TANAHCultivation 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.
http://www.gunungmadu.co.id/index.php?modul=artikel&id=utama&kodebrt=kultivasi&colvis=false …. Diunduh
12/2/2012
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.
I. Process of Soil Aeration
A. O2 availability in field1. 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 Moisture1. water saturated/waterlogged:
condition when all or nearly all of the soil pores are filled with H2O
2. adaptionC. Gas exchange
1. mass flow2. diffusion (Fig. 7.3)
PROSES DIFUSI GAS
http://www.jstor.org/pss/20113105…. Diunduh 12/2/2012
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.
AERASI TANAH
A. Composition1. O2
2. CO2 (Fig. 7.8)3. other gases
B. Air-filled porosity1. ideal composition2. O2 diffusion through
water<<<<<airC. Chemical redox potential
1. redox rxns2. 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 TANAHA. Drainage
1. Why are macropores important to soil aeration?
B. Rates of respiration2. 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 heterogeneity4. 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 vegetation7. What is an effect of one specific
type of vegetation on soil aeration?