udara tanah

DASAR ILMU TANAHDASAR ILMU TANAH

UDARA TANAH DAN UDARA TANAH DAN AERASIAERASI

diabstraksikan oleh:diabstraksikan oleh:

Prof Dr.IR.Soemarno,M.SProf Dr.IR.Soemarno,M.S..Jurusan Tanah FP UB Febr 2012Jurusan Tanah FP UB Febr 2012

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#ixzz

1mP7erq1X

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


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


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


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.


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)

…. 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 tanah yg mengandung gas tersedia dalam jumlah dan perbandingan yang tepat bagi jumlah dan perbandingan yang tepat bagi

jasad aerobik yang hidup dan mampu jasad aerobik yang hidup dan mampu menunjang berlangsungnya proses menunjang berlangsungnya proses

metabolik yg esensial bagi jasad tsb pd metabolik yg esensial bagi jasad tsb pd kecepatan yg optimumkecepatan 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


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)

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.

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.

http://www.sinauer.com/

http://www.whfreeman.com/

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)


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.


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.


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

http://www.blogdivvy.com/growing-vegetables/rainfall-water-for-your-garden.htm

http://www.blogdivvy.com/growing-vegetables/what-is-soil.htm

http://www.blogdivvy.com/growing-vegetables/what-is-soil.htm

http://www.blogdivvy.com/growing-vegetables/rainfall-water-for-your-garden.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


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


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.



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).



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


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.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


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.



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



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



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.

http://en.wikipedia.org/wiki/Soil

http://en.wikipedia.org/wiki/Oxygen

http://en.wikipedia.org/wiki/Respiration_(physiology)

http://en.wikipedia.org/wiki/Root

http://en.wikipedia.org/wiki/Carbon_dioxide

http://en.wikipedia.org/wiki/Atmosphere

http://en.wikipedia.org/wiki/Nitrogen

http://en.wikipedia.org/wiki/Oxygen

http://en.wikipedia.org/wiki/Carbon_Dioxide

http://en.wikipedia.org/wiki/Kinetic_theory_of_gases

http://en.wikipedia.org/wiki/Random_walk

http://en.wikipedia.org/wiki/Diffusion

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 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 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.)


…. 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


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


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.


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).


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.

html …. 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?

UDARATANAH

udara tanah

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