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UDARA TANAH

DASAR ILMU TANAH UDARA TANAH DAN SUHU TANAH Oleh : Prof Dr.IR.Soemarno,M.S . Jurusan Tanah FP UB Nop 2013. UDARA TANAH. Udara yang berada dalam ruang pori‐pori tanah (merupakan fraksi gas dalam sistem dispersi) Fungsinya : sebagai sumber : O2 , CO2 , N2

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UDARA TANAH

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  1. DASAR ILMU TANAHUDARA TANAH DAN SUHU TANAHOleh:Prof Dr.IR.Soemarno,M.S.Jurusan Tanah FP UB Nop 2013

  2. UDARA TANAH Udara yang berada dalam ruang pori‐pori tanah (merupakan fraksi gas dalam sistem dispersi) Fungsinya : sebagai sumber : O2 , CO2 , N2 O2 : untuk pernafasan akar, mikroorganisme & jasad/hewan dalam tanah CO2 : untuk dekomposisi & pelarutan hara N2 : sebagai suplai n tanah O2 penting dalam tanah : kadarnya ≥ 10% The air and other gases in spaces in the soil; specifically, that which is found within the zone of aeration. Also known as soil atmosphere. http://www.answers.com/topic/soil-air#ixzz1mP6ZjavG …. Diunduh 14/2/2012

  3. KEPEKAAN TANAMAN Kepekaan tanaman terhadap O2 tanah/aerasi : Tanaman yg sangat peka thdp O2 tanah/kondisi aerasi : tomat, kentang, kapri, gula bit Tanaman yg peka : jagung, gandum, kedelai Tanaman yg resisten : rumput‐rumputan Tanaman yg sangat resisten : padi‐padian If there is no air in the soil, the organic matter in the soil will begin to rot. It is called anerobic decomposition. Air in the soil allows for drainage, gives roots a place to grow, and keeps methane from building up by allowing it a ready escape. http://wiki.answers.com/Q/How_is_soil_air_important#ixzz1mP6xpcrT …. Diunduh 7/2/2012

  4. AERASI TANAH Pengharkatan kondisi aerasi : Porositas total : jumlah total pori tanah ( yg terisi udara & air) dinyatakan dlm % volume tanah (jmlh pori mikro & makro) Volume total tanah : Vs + Va + Vw = 1 1 – Vs = Va + Vw Va + Vw = porositas total ( n ) n = ( 1 – bv/bj ) x 100% It is important for air to get into soil, as plants need oxygen to survive. Without air, plants would die, and therefore disrupt the food wed of the environment it is in. http://wiki.answers.com/Q/Why_is_it_important_for_air_to_get_into_soil#ixzz1mP7KzWEA …. Diunduh 7/2/2012

  5. KAPASITAS UDARA EFEKTIF Kapasitas udara/aktual/efektif : bagian ruang pori tanah yang terisi udara, dinyatakan dalam % volume tanah n – Vw = { n – (%KL x BV)} Vw = %KL x BV Kapasitas udara selalu berfluktuasi tergantung : KL tanah Struktur tanah Permukaan air tanah (GROUNDWATER) Soil Pore For plant roots and animals to move through it and for the animals to breath.It is important because the microorganisms living in under the soil take these oxygen.It is also important for anaerobic respiration.You will also find that the earthworms live under the soil takes oxygen deep below in the soil. http://wiki.answers.com/Q/Why_is_it_important_for_soil_to_have_air_spaces_in_it#ixzz1mP7erq1X …. Diunduh 14/2/2012

  6. KAPASITAS AERASI TANAH Kapasitas aerasi/porositas aerasi/porositas non kapiler : yaitu kapasitas udara pada saat lengas tanah mencapai kapasitas lapang (persen total pori non kapiler/makro) Kapasitas aerasi = n – (KL KAP. LAP. X BV) Soil porosity (f) is the ratio of pore volume (Vf) to total soil volume (Vt) f = Vf / Vt It is generally between 30-60%.  Porosity tells us nothing about the relative amounts of large and small pores, and should be interpreted with caution. Generally, high porosity (e.g. 60%) is an indicator of lack of compaction and good soil conditions. http://www.landfood.ubc.ca/soil200/components/air.htm…. Diunduh 7/2/2012

  7. FAKTOR KOMPOSISI UDARA TANAH Faktor‐faktor yang mempengaruhi komposisi udara tanah : Iklim Sifat tanah seperti tekstur, struktur, tinggi permukaan air tanah Sifat tanaman Keterdapatan tanaman mengurangi kadar O2 dan menambah CO2, bo dan kegiatan jasad renik CO2 > (jika aerob), CH4 > (jika anaerob). The composition of soil air is different from that of the atmosphere because it cannot readily mix with air above the soil. The metabolic activity of plant roots, microbes and soil fauna all affect the composition of soil air. For example, the concentration of carbon dioxide (CO2) in soil (between 0.3 and 3%) is often several hundred times higher than the 0.03% found in the atmosphere. In extreme cases oxygen can be as low as 5-10%, compared to 20% in the atmosphere. Soil air has a higher moisture content than the atmosphere, with relative humidity approaching 100% under optimum conditions. (humidity is not as variable in soil as it is in the atmosphere).   The amount and composition of air in soil are dynamic and to a large degree are determined by water content and activity of soil organisms.   http://www.landfood.ubc.ca/soil200/components/air.htm…. Diunduh 7/2/2012

  8. KOMPOSISI UDARA TANAH Tergantung dari proses biologi serta sukar mudahnya tukar menukar dengan udara atmosfer Contoh udara tanah sawah yang bebas air …. Diunduh 7/2/2012

  9. Secara riil komposisi udara tanah dibanding udara atmosfer, sebagai berikut Growth of most plants and survival of their roots normally requires maintenance of adequate soil oxygen.  This in turn requires maintainance of soil water well below saturation, to enable rapid gas diffusion in the soil.  …. Diunduh 7/2/2012

  10. PERTUKARAN UDARA Komposisi tersebut selalu berubah‐ubah tergantung beberapa faktor yaitu : Kecepatan pertukaran udara tanah dan atmosfer, tergantung : o Tanah : tekstur, struktur, B.O, KL, suhu o Iklim : angin, tekanan udara, & suhu o Kedalaman dari muka tanah The exchange of gases between the atmosphere and soil is facilitated by two mechanisms: (1)   Mass flow (convection) of air - the moving force is a gradient of total gas pressure, and it results in the entire mass of air streaming from a zone of higher pressure to one of lower pressure. Mass flow of air is much less important than diffusion, except perhaps in layers at or very near the soil surface. (2)   Diffusion - moving force is gradient of partial pressure of any constituent member of air to migrate from a zone of higher to lower pressure, even while air as a whole may remain stationary. In other words, through diffusion each gas moves in a direction determined by its own partial pressure. http://www.landfood.ubc.ca/soil200/components/air.htm…. Diunduh 7/2/2012

  11. Pertukaran Udara Tanah/Pembaruan Komposisi Udara Tanah Pertukaran udara tanah & udara atmosfer dapat terjadi karena adanya gerakan udara. Ada 3 faktor yg mempengaruhi pembaruan udara dalam tanah; yaitu : Proses difusi Aliran masa gas Air hujan The oxygen flux density due to diffusion is proportional to the oxygen concentration gradient along the axis, and the proportionality factor is called the (oxygen) diffusion coefficient (D). This statement is an example of Fick’s Law of Diffusion, which can be expressed as follows: J = - D dC/dX where J is the diffusive flux density of the gas (oxygen in this example) (mg/m2/s) along the x-axis, C is oxygen concentration in the soil air (units are g/m3), x is distance along x-axis (m), dC/dx is the oxygen concentration gradient (g/m4), and D is the (oxygen) diffusion coefficient (m2/s). http://www.landfood.ubc.ca/soil200/components/air.htm…. Diunduh 7/2/2012

  12. 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

  13. ALIRAN MASSA GAS Aliran Massa Gas terjadi karena perbedaan tekanan total udara dalam tanah dan udara atmosfer, hal ini terjadi kalau : Suhu tanah berubah Lengas tanah Kecepatan angin di atas tanah berubah http://www.hissan.co.jp/business/moda/e_index.html …. Diunduh 14/2/2012

  14. PENGARUH AERASI (TATA UDARA) DALAM TANAH Perbaikanaerasitanahakanberpengaruhterhadap : Peningkatankegiatan M.O Peningkatanpenguraian B.O Peningkatanstrukturisasi Pencegahanterbentuknyasenyawa TOKSIK : Methan Amonia H2S N2 Nitrit Senyawa‐senyawaferro …. Diunduh 14/2/2012

  15. PENGELOLAAN UDARA TANAH Pengelolaan udara tanah ditujukan untuk mempercepat proses difusi dan aliran massa gas, dengan usaha : Perbaikan struktur tanah Pengendalian lengas tanah http://www.uraniumresources.com/isr-technology/photo-gallery …. Diunduh 14/2/2012

  16. UDARA TANAH - PENGELOLAAN Tindakan‐tindakan yang dapat dilakukan : Menghindari terbentuknya lapisan cadas serta pemampatan tanah Pengolahan tanah yang tepat Penambahan B.O. ke dalam tanah Pemberian mulsa Perbaikan drainase. http://www.extension.org/pages/18634/use-of-tillage-in-organic-farming-systems:-the-basics …. Diunduh 14/2/2012

  17. Tanah yang AERASI nya baik adalah tanah yg mengandung gas tersedia dalam jumlah dan perbandingan yang tepat bagi jasad aerobik yang hidup dan mampu menunjang berlangsungnya proses metabolik yg esensial bagi jasad tsb pd kecepatan yg optimum Tanah yang AERASI nya baik mempunyai sifat: 1. Harus ada ruangan yang cukup tanpa bahan mineral dan air 2. Harus ada kesempatan yg cukup bagi gas-gas untuk keluar-masuk ruangan tsb AERASI TANAH 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

  18. Penyebab buruknya aerasi tanah: 1. Kandungan air tanah yg berlebihan shg tidak menyisakan ruangan untuk gas/ udara 2. Pertukaran gas tidak cukup cepat unt mempertahankan kadarnya pd tingkat tertentu. Air Tanah yang berlebihan 1. Tanah jenuh air, tanah tergenang dapat berpengaruh buruk pd tanaman pd umumnya 2. Biasanya pd tanah-tanah yg drainasenya buruk dan tekstur halus 3. Pada tempat-tempat cekungan MASALAH AERASI TANAH 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

  19. LDO adalah laju pergantian oksigen dalam tanah yg dipakai oleh akar tanaman yg bernafas atau digantikan oleh air. Nilai LDO semkin kecil dengan kedalaman tanah LDO pada kedalaman 95 cm sama dengan setengah nilai LDO pd kedalaman 11.5 cm LAJU DIFUSI OKSIGEN (LDO) Pertumbuhan akar tanaman berhenti bila LDO turun menjadi 20 g x 10-8 cm2/menit

  20. 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 % volume: Tempat O2 CO2 N2 Udaratanah: New York 15.10 4.50 81.40 Inggris 20.65 0.25 79.20 UdaraAtmosfer Inggris 20.97 79.00 Sumber: Lyon, Buckman & Brady, 1952. SUSUNAN UDARA TANAH

  21. Susunan udara tanah tgt pada: 1. Jumlah ruangan / pori yg tersedia 2. Kecepatan reaksi biokimia 3. Pertukaran gas Penambahan bahan organik akan mengubah susunan udara tanah Tanah lapisan atas vs Tanah lapisan bawah Jumlah total ruangan pori tanah lapisan bawah lebih sedikit dibanding tanah lapisan atas % CO2 udaratanahKedalaman sampling, cm 0.5 gandum + rabuk 30 tanahbera + rabukkandangLempungliatberdebu Lempungberdebu tanahbera 180 Waktu sampling 10 20 % O2 udratnh Faktor Susunan Udara Tanah

  22. Jasad Mikro 1. Aerasi buruk menurunkan oksidasi bahan organik tanah 2. Penurunan ini lebih disebabkan oleh kekurangan O2 3. Populasi jasad renik sangat terpengaruhi olh aerasi 4. Aerasi buruk mendorong aktifitas jasad anaerob dan fakultatif, menghasilkan senyawa reduksi, fero, mangano, sulfida Aerasi b uruk mempengaruhi Tanaman: 1. Pertumbuhan perakaran sangat terbatas 2. Penyerapan hara terhambat 3. Air menjadi berkurang 4. Pembentukan senyawa anorganik yang bersifat toksik AERASI & KEGIATAN BIOLOGIS 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.

  23. Dekomposisianaerobik C6H12O6 3CO2 + 3 CH4 gulametan TanamanTekstur LDO padakedalaman: Kondisi 10 cm 20 cm 30 cm pertumbuhan tanaman BrokoliLempung 53 31 38 Sangatbaik SeladaLempungberdebu 49 26 32 Baik Phaseolus sp Lempung 27 27 25 Klorosis ArbeiLempungberpasir 36 32 34 Klorosis KapasLempingberliat 7 9 - Klorosis JerukLempungberpasir 64 45 39 Pertumbuhanakar cepat Sumber: StolzydanLetey, 1964. AERASI & EFEK LAIN Kondisiaerasitanahberpengaruhterhadapbentukunsurharapenting: UnsurKondisiOksidasiKondisireduksi (tergenang) Karbon CO2 CH4 Nitrogen NO3- N2, NH4+ Belerang SO4= H2S, S=

  24. Tindakan untuk memperbaiki aerasi ntanah: 1. Menghilangkan air yang berlebihan (drainase) 2. Memperbaiki agregasi dan pengolahan tanah Adaptasi Tanaman-Tanah : 1. Pohon buah-buahan dan tanaman berakar dalam memerlukan solum tanah yang dalam (tebal), aerasinya baik, dan sangat peka terhadap kekurangan oksigen dalam tanah 2. Pengelolaan tanaman ditentukan oleh baik-buruknya aerasi tanah AERASI & KEGIATAN Pengelolaan

  25. Suhu tanah sangat vital bagi aktivitas biologis dalam tanah, termasuk pertumbuhan akar tanaman. Proses nitrifikasi baru dapat berlangsung kalau suhu tanah telah mencapai 5oC, batas optimumnya 27 - 33oC Suhu tanah di lapangan ditentukan oleh: 1. Jumlah panas yang diserap oleh tanah 2. Energi panas yg diperlukan untuk mengubah suhu tanah 3. Energi yg diperlukan untuk evaporasi yg terus menerus di permukaan tanah SUHU TANAH Amplitude of seasonal soil temperature change as a function of depth below ground surface. Sumber: http://www.geo4va.vt.edu/A1/A1.htm

  26. Jumlah panas yg diserap tanah ditentukan oleh radiasi efektif yg mencapai permukaan tanah dan iklim Jumlah energi yg masuk tanah dipengaruhi oleh: 1. Warna tanah: gelap menyerap lebih banyak energi 2. Lereng: 3. Tanaman penutup tanah: Hutan vs. tanah gundul Tanah gundul lebih cepat memanas dan mendingin Kehilangan panas dari tanah ke atmosfer, melalui KONDUKSI dan RADIASI Radiasi ini berupa infra merah, tidak terlihat mata, gelombang gelap Radiasi gelombang gelap ini berenergi tinggi dan selama pemancarannya banyak panas yg hilang dari tanah Thermal Admittance (λ/Cv) 1/2 : Represents ability of soil to accept and release heat.  Soils with low thermal admittance have extreme surface temperature fluctuations. Because water has a HIGH heat capacity and is a GOOD conductor, wet soils will have a HIGH thermal admittance.. SERAPAN & KEHILANGAN PANAS Thermal Admittance Source: Lesley Dampier

  27. Panas jenis tanah: Jumlah panas yang diperlukan oleh satu gram tanah untuk menaikkan suhunya satu derajat celcius. Panas jenis tanah kering lebih rendah dibandingkan dg tanah basah Tanah kering : PJ = 0.20 Kadar air 20% : PJ = 0.33 Kadar air 30% : PJ = 0.38 Thermal Conductivity (λ): Measure of the ease with which a soil transmits heat.It describes heat flow in response to a temperature gradient.. PANAS JENIS TANAH Thermal Conductivity Source: Lesley Dampier

  28. Penguapan air tanah memerlukan sejumlah energi panas Untuk menguapkan 1 g air pada 20oC diperlukan panas 585 kalori. Penguapan 0.452 g air memerlukan 265 kalori. Bila semua panas ini diambil dari tanah dan air, maka tanah sedalam 30 cm menjadi dingin dan suhunya sama dengan -2oC. Warna tanah vs. Suhu Tanah gelap biasanya kaya bahan organik dan kandungan airnya tinggi. Tanah gelap yg drainasenya buruk lambat memanas. Soil Heat Capacity (Cv): Amount of heat needed to cause a 1oC change in temperature of a unit volume of soil. PANAS PENGUAPAN Soils with high Cv are buffered against temperature change . It is much easier to raise soil temperature by 1oC in a dry soil than wet soil Heat Capacity Source: Lesley Dampier

  29. Energi panas masuk ke dalam tanah melalui proses konduksi, sehingga kadar air tanah sangat menentukan laju konduksi ini. Energi panas lebih mudah menjalar dari tanah ke air dibandingkan dari tanah ke udara Proses konduksi panas dalam tanah berlangsung lambat. Tanah lapisan bawah suhunya lebih rendah dp tanah lapisan atas. Perubahan suhu tanah lapisan bawah sangat sedikit sekali Thermal Diffusivity (λ/C): An indication of subsurface temperature response to surface temperature change.. Soils with high thermal diffusivity undergo large and rapid subsurface temperature responses to surface temperature change.. Does not change much with water content in organic soil, but in mineral soils, the peak thermal diffusivity occurs near field capacity GERAKAN PANAS DALAM TANAH Heat Capacity Source: Lesley Dampier

  30. Suha tanah pada suatu saat tergantung pada nisbah energi panas yang diserap dan yang hilang Suhu tanah juga tergantung kedalaman tanah Suhutanah. oC 15 20 25 30 35 Soil depth cm 60 JanuariJuli 300 Sumber: Fluker, 1956 (Texas) SUHU TANAH

  31. Penggunaan mulsa organik mengakibatkan suhu tanah lebih rendah dan lebih merata Pengelolaan air tanah secara tepat juga akan mempengaruhi suhu tanah Suhu oC Kedalaman tanah 1.5 cm Kedalaman tanah 15 cm 38 tanpa mulsa Dengan mulsa Tanpa mulsa Dengan mulsa pagi sore pagi sore Pengendalian Suhu Tanah

  32. 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 

  33. ‘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/

  34. Lawn Aeration for a Greener, Thicker, Healthier Lawn! More Benefits of Lawn Aeration Aeration loosens compacted soil and breaks up thatch. It allows water and other nutrients to seep into the soil, encouraging new root growth and establishing a stronger, deeper root base for a lusher, healthier turf. Another benefit of aeration is the reduction of water runoff and puddling. Lawn Aeration permits the root system to go deeper where the ground temperature is cooler and moister, allowing the grass to stay greener longer in the heat of the summer. Remember, 90% of grass is in the roots! A healthy root system is a must for an attractive lawn. Oxygen in the soil is vital for healthy roots. Root growth is inhibited by clay and compacted soils because of a restricted oxygen supply. Aerating improves rooting and problem soils by allowing air into the soil. Umber: http://yardplug.com/FAQ/FAQ1.htm

  35. 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

  36. Mechanism of Gas Exchange in Soils: Mencegah defisiensi O2 atau toksisitas CO2 Mekanisme pergerakan gas Mass Flow Movement of a mass of air (gases move together Driven by gradients in total pressure differences   Caused by changes in temperature (ideal gas law) Caused by movement of water downward   Diurnal flow of air in upper few inches (soil breath?) Diffusion Each gas moves down gradients of its own concentration   Even with no overall pressure difference   O2 and CO2 diffusing past each other in opposite directions Sumber; http://faculty.plattsburgh.edu/robert.fuller/370%20Files/Weeks13Soil%20Air%20&%20Temp/aastart14.htm

  37. 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

  38. Faktor-faktor yang mempengaruhi Aerasi Excess Moisture    -   diffusion of water very slow through water Soil texture    -  heavy soils    -   reduced pore size, greater resistance   Poor Structure   -  macropores increase ODR   Position on Slope    -   excess moisture at bottom Impermeable Layers   Soil Depth  -    subsoils farther away from surface  (less ODR) Rate of O2 consumption (high labile OM content) Sumber; http://faculty.plattsburgh.edu/robert.fuller/370%20Files/Weeks13Soil%20Air%20&%20Temp/aastart14.htm

  39. POTENSIAL REDOKS (Eh) Measured with a platinum (redox) electrode attached to a pH meter. Ranges from -400 millivolts (reducing) to +600 mV (oxidizing conditions) Measure of the relative concentration of reduced vs. oxidized forms Reduced forms have available electrons, carried by H, or less positive charge;   Oxidized forms have more O, or higher positive charge   Sensitive roots are adversely affected below +300 mV   Other plants are tolerant (adaptations, such as aerenchyma)   As O2 availability declines:  step down through bacteriological reactions using alternate oxidants. Sumber; http://faculty.plattsburgh.edu/robert.fuller/370%20Files/Weeks13Soil%20Air%20&%20Temp/aastart14.htm

  40. Structure of soil, indicating presence of bacteria, inorganic, and organic matter, water, and air. Image from Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Associates (www.sinauer.com) and WH Freeman (www.whfreeman.com). Posisi dan lokasi udara dalam pori, di dalam struktur tanah Macropores (d>0.08mm) occur between aggregates (interped pores) or individual grains in coarse textured soil (packing pores) and may be formed by soil organisms (biopores).  They allow ready movement of air and the drainage of water and provide space for roots and organisms to inhabit the soil. SUMBER: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPLANTHORM.html

  41. TEKSTUR TANAH: THE KEY TO MANAGEMENT OF SOIL – PLANT – WATER RELATIONSHIP Soil is the voluminous upper part of the earth crust that consists of unconsolidated inorganic particles and organic fragments with pore spaces between and within them. Pore spaces contain soil air, and soil solution. In other words, soil volume consists of solid, liquid and gaseous phases. .SUMBER: http://www.ecoconsulting.com/balance.htm

  42. Perbandingan antara komposisi udara tanah dan atmosfir Sumber: http://www.ctahr.hawaii.edu/mauisoil/a_comp04.aspx

  43. Kandungan O2 dan CO2 pada berbagai kedalaman tanah (Trinidad) Sumber: http://www.ctahr.hawaii.edu/mauisoil/a_comp04.aspx

  44. 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: An increase in soil water content often causes a reduction in soil aeration. Likewise, reducing soil water content may mean an increase in soil aeration. Since plant roots require water and oxygen (from the air in pore spaces), maintaining the balance between root and aeration and soil water availability is a critical aspect of managing crop plants. Sumber: http://www.ctahr.hawaii.edu/mauisoil/a_comp04.aspx

  45. ARTMOSFER TANAH The soil atmosphere is not uniform throughout the soil because there can be localized pockets of air. The relative humidity of soil air is close to 100%, unlike most atmospheric humidity. Air in the soil often contains several hundred times more carbon dioxide. Sumber: http://www.ctahr.hawaii.edu/mauisoil/a_comp04.aspx

  46. 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

  47. SIFAT OLAH TANAH Soil tilth is a measurement of the balance between basic soil elements: mineral, air, water and organic matter. The proper balance of these elements increases soil production by allowing efficient interaction of all the soil systems. Air and water balance in the soil is the key to good root growth. Sumber: http://rbmc.com.au/aerway.htm

  48. PORI DAN UDARA TANAH Soil pores, the voids between minerals, organic matter, and living organisms, are filled with air or water. There is a dynamic equilibrium between water and air content within a soil. When water enters the soil, it displaces air from some of the pores. 1. Composition of soil air2. Movement of gasses within soil 3. Soil porosity Source: Lesley Dampier Sumber: http://www.landfood.ubc.ca/soil200/components/air.htm Sumber: http://www.landfood.ubc.ca/soil200/interaction/water_air.htm

  49. KOMPOSISI UDARA TANAH The composition of soil air is different from that of the atmosphere because it cannot readily mix with air above the soil. The metabolic activity of plant roots, microbes and soil fauna all affect the composition of soil air. For example, the concentration of carbon dioxide (CO2) in soil (between 0.3 and 3%) is often several hundred times higher than the 0.03% found in the atmosphere. In extreme cases oxygen can be as low as 5-10%, compared to 20% in the atmosphere. Soil air has a higher moisture content than the atmosphere, with relative humidity approaching 100% under optimum conditions. (humidity is not as variable in soil as it is in the atmosphere).   The amount and composition of air in soil are dynamic and to a large degree are determined by water content and activity of soil organisms. Sumber: http://www.landfood.ubc.ca/soil200/components/air.htm

  50. PERGERAKAN GAS DALAM TANAH Ada dua mekanisme yang memfasilitasi pertukaran gas antara TANAH dan ATMOSFIR: 1)   MASS FLOW (convection) of air - the moving force is a gradient of total gas pressure, and it results in the entire mass of air streaming from a zone of higher pressure to one of lower pressure. Mass flow of air is much less important than diffusion, except perhaps in layers at or very near the soil surface. 2)   DIFFUSION - moving force is gradient of partial pressure of any constituent member of air to migrate from a zone of higher to lower pressure, even while air as a whole may remain stationary. In other words, through diffusion each gas moves in a direction determined by its own partial pressure. Sumber: http://www.landfood.ubc.ca/soil200/components/air.htm

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