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DASAR ILMU TANAH UDARA TANAH DAN AERASI diabstraksikan oleh: Prof Dr.IR.Soemarno,M.S. Jurusan Tanah FP UB Febr 2012.

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Presentasi berjudul: "DASAR ILMU TANAH UDARA TANAH DAN AERASI diabstraksikan oleh: Prof Dr.IR.Soemarno,M.S. Jurusan Tanah FP UB Febr 2012."— Transcript presentasi:

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2 DASAR ILMU TANAH UDARA TANAH DAN AERASI diabstraksikan oleh: Prof Dr.IR.Soemarno,M.S. Jurusan Tanah FP UB Febr 2012

3 UDARA TANAH …. Diunduh 14/2/2012 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. air#ixzz1mP6ZjavG

4 KEPEKAAN TANAMAN …. Diunduh 7/2/2012 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. xzz1mP6xpcrT

5 AERASI TANAH …. Diunduh 7/2/2012 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. t_for_air_to_get_into_soil#ixzz1mP7KzWEA

6 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 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. have_air_spaces_in_it#ixzz1mP7erq1X

7 KAPASITAS AERASI TANAH Diunduh 7/2/2012 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 (V f ) to total soil volume (V t ) f = V f / V t 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.

8 FAKTOR KOMPOSISI UDARA TANAH Diunduh 7/2/2012 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 (CO 2 ) 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.

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

10 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 dibanding udara atmosfer, sebagai berikut

11 PERTUKARAN UDARA Diunduh 7/2/2012 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.

12 Pertukaran Udara Tanah/Pembaruan Komposisi Udara Tanah Diunduh 7/2/2012 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/m 2 /s) along the x-axis, C is oxygen concentration in the soil air (units are g/m 3 ), x is distance along x-axis (m), dC/dx is the oxygen concentration gradient (g/m 4 ), and D is the (oxygen) diffusion coefficient (m 2 /s).

13 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 (V a /V t ), 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. Diunduh 7/2/2012

14 ALIRAN MASSA GAS …. Diunduh 14/2/2012 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

15 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 ( liter air hujan ~ ± 4000 gram O2)

16 …. Diunduh 14/2/2012 PENGARUH AERASI (TATA UDARA) DALAM TANAH Perbaikan aerasi tanah akan berpengaruh terhadap : Peningkatan kegiatan M.O Peningkatan penguraian B.O Peningkatan strukturisasi Pencegahan terbentuknya senyawa TOKSIK : Methan Amonia H2S N2 Nitrit Senyawa ‐ senyawa ferro

17 PENGELOLAAN UDARA TANAH …. Diunduh 14/2/2012 Pengelolaan udara tanah ditujukan untuk mempercepat proses difusi dan aliran massa gas, dengan usaha : Perbaikan struktur tanah Pengendalian lengas tanah

18 UDARA TANAH - PENGELOLAAN farming-systems:-the-basics …. Diunduh 14/2/2012 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.

19 AERASI TANAH 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 adalah tanah yg mengandung gas tersedia dalam jumlah dan perbandingan yang tepat bagi jasad aerobik yang hidup dan mampu menunjang berlangsungnya proses metabolik yg esensial bagi jasad tsb pd kecepatan yg optimum Tanah yang AERASI nya baik mempunyai sifat: 1. Harus ada ruangan yang cukup tanpa bahan mineral dan air 2. Harus ada kesempatan yg cukup bagi gas-gas untuk keluar-masuk ruangan tsb Dua reaksi biologis yg terkait dgn dinamika O2 dan CO2 dalam tanah: 1. Pernafasan akar tumbuhan tinggi 2. Dekomposisi bahan organik tanah secara aerobik oleh jasad renik. (C) + O2 CO2

20 MASALAH AERASI TANAH Air Tanah yang berlebihan 1. Tanah jenuh air, tanah tergenang dapat berpengaruh buruk pd tanaman pd umumnya 2.Biasanya pd tanah-tanah yg drainasenya buruk dan tekstur halus 3. Pada tempat-tempat cekungan PERTUKARAN GAS antara tanah dan atmosfer tgt pd: 1. Laju reaksi biokimia yg mempengaruhi gas dlm tanah 2. Laju ke luar - masuknya gas-gas dari dan ke dalam tanah. Pertukaran gas ini terjadi melalui mekanisme: 1. Pergerakan masal (mass flow) 2. Difusi gas 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.

21 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 cm 2 /menit LDO adalah laju pergantian oksigen dalam tanah yg dipakai oleh akar tanaman yg bernafas atau digantikan oleh air.

22 SUSUNAN UDARA TANAH % volume: TempatO2CO2 N2 Udara tanah: New York Inggris Udara Atmosfer Inggris Sumber: Lyon, Buckman & Brady, 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

23 Faktor Susunan Udara Tanah Tanah lapisan atas vs Tanah lapisan bawah Jumlah total ruangan pori tanah lapisan bawah lebih sedikit dibanding tanah lapisan atas % CO2 udara tanahKedalaman sampling, cm 0.5 gandum + rabuk 30 tanah bera + rabuk kandang Lempung liat berdebu Lempung berdebu tanah bera 180 Waktu sampling % O2 udra tnh 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

24 AERASI & KEGIATA N BIOLOGIS 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 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 Akar tanaman apel memerlukan minimal 3% O2 dalam udara tanah, sedangkan % 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 g x /cm2/menit.

25 AERASI & EFEK LAIN Tanaman TeksturLDO pada kedalaman: Kondisi 10 cm 20 cm 30 cm pertumbuhan tanaman Brokoli Lempung Sangat baik Selada Lempung berdebu Baik Phaseolus sp Lempung Klorosis Arbei Lempung berpasir Klorosis Kapas Lemping berliat79- Klorosis Jeruk Lempung berpasir Pertumbuhan akar cepat Sumber: Stolzy dan Letey, Dekomposisi anaerobik C6H12O6 3CO2 + 3 CH4 gula metan Kondisi aerasi tanah berpengaruh terhadap bentuk unsur hara penting: UnsurKondisi OksidasiKondisi reduksi (tergenang) KarbonCO2CH4 NitrogenNO3-N2, NH4+ BelerangSO4=H2S, S=

26 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

27 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 oC Sumber: Amplitude of seasonal soil temperature change as a function of depth below ground surface.

28 SERAPAN & KEHILANG AN PANAS 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 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 Thermal Admittance (λ/Cv) 1/2 : Represents ability of soil to accept and release heat. Soils with low thermal admittance have extreme surface temperature fluctuations. Because water has a HIGH heat capacity and is a GOOD conductor, wet soils will have a HIGH thermal admittance.. Thermal Admittance Source: Lesley Dampier

29 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 = 0.20 Kadar air 20%: PJ = 0.33 Kadar air 30%: PJ = 0.38 Thermal Conductivity Source: Lesley Dampier

30 PANAS PENGUAP AN Warna tanah vs. Suhu Tanah 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 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 Capacity Source: 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

31 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 Capacity Source: Lesley Dampier

32 SUHU TANAH Suhu tanah. oC Soil depth cm 60 Januari Juli 300Sumber: Fluker, 1956 (Texas) Suha tanah pada suatu saat tergantung pada nisbah energi panas yang diserap dan yang hilang Suhu tanah juga tergantung kedalaman tanah

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

34 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: htm

35 ‘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: health/

36 Lawn Aeration for a Greener, Thicker, Healthier Lawn! Umber: 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.

37 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

38 Mechanism of Gas Exchange in Soils: Mencegah defisiensi O 2 atau toksisitas CO 2 Sumber; p/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 O 2 and CO 2 diffusing past each other in opposite directions

39 Function of concentration gradient and resistance Resistance: Increases with reductions in pore size O 2 gradient: Decreases with depth due to O 2 consumption Gradient decreases with depth; less ODR. O 2 Diffusion rate (ODR) : Rate of movement across a cross-sectional area ; ug O 2 /cm 2. minute Sumber; emp/aastart14.htm

40 Faktor-faktor yang mempengaruhi Aerasi Sumber; emp/aastart14.htm 1.Excess Moisture - diffusion of water very slow through water 2.Soil texture - heavy soils - reduced pore size, greater resistance 3.Poor Structure - macropores increase ODR 4.Position on Slope - excess moisture at bottom 5. Impermeable Layers 6.Soil Depth - subsoils farther away from surface (less ODR) 7. Rate of O 2 consumption (high labile OM content)

41 POTENSIAL REDOKS (Eh) Sumber; p/aastart14.htm Measured with a platinum (redox) electrode attached to a pH meter. Ranges from 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.

42 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).www.sinauer.comwww.whfreeman.com SUMBER: 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.

43 TEKSTUR TANAH: THE KEY TO MANAGEMENT OF SOIL – PLANT – WATER RELATIONSHIP.SUMBER: 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.

44 Perbandingan antara komposisi udara tanah dan atmosfir Sumber:

45 Kandungan O2 dan CO2 pada berbagai kedalaman tanah (Trinidad) Sumber:

46 UDARA TANAH Air can fill soil pores as water drains or is removed from a soil pore by evaporation or root absorption. The network of pores within the soil aerates, or ventilates, the soil. This aeration network becomes blocked when water enters soil pores. Not only are both soil air and soil water very dynamic parts of soil, but both are often inversely related: 1.An increase in soil water content often causes a reduction in soil aeration. 2.Likewise, reducing soil water content may mean an increase in soil aeration. 3.Since plant roots require water and oxygen (from the air in pore spaces), maintaining the balance between root and aeration and soil water availability is a critical aspect of managing crop plants. Sumber:

47 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:

48 KOMPONEN UTAMA TANAH ADALAH: Air, Udara, 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.soil This way air can easily circulate through the soil to reach plant roots and allow water to drain easily.soilwater The solid portion is mostly rock particles and bits of dead material and organic matter. Sumber: soil.htm

49 SIFAT OLAH TANAH Sumber: 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.

50 PORI DAN UDARA TANAH Sumber: 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 air 2. Movement of gasses within soil 3. Soil porosity Sumber: 00/interaction/water_air.htm Source: Lesley Dampier

51 KOMPOSISI UDARA TANAH Sumber: 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 (CO 2 ) 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.

52 PERGERAKAN GAS DALAM TANAH Sumber: 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.

53 PERGERAKAN GAS DALAM TANAH Sumber: 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/m 2 /s) along the x-axis, C is oxygen concentration in the soil air (units are g/m 3 ), x is distance along x-axis (m), dC/dx is the oxygen concentration gradient (g/m 4 ), and D is the (oxygen) diffusion coefficient (m 2 /s).

54 PERGERAKAN GAS DALAM TANAH Sumber: 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 (V a /V t ), 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.

55 POROSITAS TANAH Sumber: Soil porosity (f) is the ratio of pore volume (V f ) to total soil volume (V t ) f = V f / V t 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.

56 KOMPOSISI UDARA TANAH Sumber: 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.

57 FAKTOR YANG MEMPENGARUHI KOMPOSISI UDARA TANAH Sumber: 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.

58 FAKTOR YANG MEMPENGARUHI KOMPOSISI UDARA TANAH Sumber: 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. _library/howardAT/AT9b.html

59 FAKTOR YANG MEMPENGARUHI KOMPOSISI UDARA TANAH Sumber: 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. microbial-nitrogen-cycling-for-organic-farms

60 FAKTOR YANG MEMPENGARUHI KOMPOSISI UDARA TANAH Sumber: 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.

61 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.soiloxygenrespirationroots carbon dioxide KomposiSI UDARA dalam TANAH dan atmosphere:atmosphere NitrogenNitrogen: Soil Air: 79.2% Atmosphere: 79.0% OxygenOxygen: Soil Air: 20.6% Atmosphere: 20.9% Carbon DioxideCarbon 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.kinetic theory of gasesrandom 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.diffusion Numerically, it is explained by Fick's law of diffusion.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. air leakage 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.

62 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 PhytologistNew Phytologist > Vol. 88, No. 4, Aug., 1981 …. Diunduh 7/2/2012Vol. 88, No. 4, Aug., 1981 OKSIGEN DALAM UDARA TANAH

63 AERASI TANAH - HASIL TANAMAN SoilSoil 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.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.soil …. Diunduh 7/2/2012

64 THE EFFECT OF SOIL WATER AND AERATION ON SEED GERMINATION S. DASBERGS. DASBERG and K. MENDELK. MENDEL The Volcani Institute of Agricultural Research Bet Dagan, Israel Received January 25, 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): …. Diunduh 7/2/2012

65 ISHS Acta Horticulturae 563: International Conference on Environmental Problems Associated with Nitrogen Fertilisation of Field Grown Vegetable Crops EFFECT OF SOIL AERATION ON NITROGEN AVAILABILITY AND GROWTH OF SELECTED VEGETABLES-PRELIMINARY RESULTS H. Heuberger, J. Livet, W. Schnitzler After heavy rainfall or irrigation, the macropores of the soil are filled with water leading to limited gas diffusion and reduced oxygen content of the soil air for a certain period of time. In this situation, soil aeration by means of forced injection of atmospheric air into the soil via a subsurface drip irrigation system, is thought to accelerate the depletion of water from macropores and increase the oxygen concentration in the soil air. In 1999, cauliflower (Brassica oleracea L. convar. botrytis (L.) Alef. var. botrytis L.), cv. 'Fargo' and sweet corn (Zea mays L. convar. saccharata Koern.), cv. 'Tasty Sweet' were grown in a silty clay loam under varying drip irrigation, fertigation, and aeration conditions. The drip laterals for irrigation (S-I) and fertigation (S-F) were placed 5 cm below the soil surface. In another fertigation treatment (Sub-F) and for fertigation cum aeration (Sub-F-A), the laterals were placed at 15 cm soil depth (Subsurface). Nitrogen fertilisation was 250 kg N/ha for cauliflower and 180 kg N/ha for sweet corn with basal application and top dressing in S-I and fertigation after basal application in the fertigated treatments. compared to S-I (single-plot comparison). …. Diunduh 7/2/2012

66 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

67 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 Vol. 39 No. 5, p …. Diunduh 7/2/2012

68 ISHS Acta Horticulturae 504: VI Symposium on Stand Establishment and ISHS Seed SymposiumVI 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.

69 THE IMPACT OF SOIL COMPACTION ON SOIL AERATION AND FINE ROOT DENSITY OF Quercus palustris G Watson, P Kelsey Urban Forestry Urban Greening (2006) Volume: 4, Issue: 2, Pages: …. Diunduh 7/2/ 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 Soil oxygen diffusion rate (ODR), fine root density (FRD), DBH, twig growth, leaf area and dieback were monitored for 4 years beginning in 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., Correlation of plant response to soil oxygen diffusion rates. Hilgardia 35, 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.

70 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) , /S Diunduh 7/2/ 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 (NH 3 ) flux emissions from both aerated and control plots. For all eight trials, the manure application rate was L ha −1. The average NH 3 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 NH 3 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 to 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

71 American Journal of BotanyAmerican Journal of Botany Vol. 66, No. 6, Jul., 1979.Vol. 66, No. 6, Jul., 1979 The Effect of Aeration on the Growth of Spartina alterniflora Loisel.The Effect of Aeration on the Growth of Spartina alterniflora Loisel.(pp ) Rick A. Linthurst 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.

72 AERASI TANAH …. Diunduh 7/2/2012 The ventilation of soil – rate of gas exchange Aerasi tanah dipengaruhi oleh: – Porositas tanah – Kandungan lengas tanah – Oxygen consumption by organisms Saturated soil = anaerobic: O2 has low solubility in H2O and slow rate of dissolution O2 present = aerobic (oxic); O2 absent = anaerobic (red.)

73 KOMPOSISI UDARA TANAH …. Diunduh 7/2/2012 Air above soil: 21% O2, 0.035% CO2, 78% N2 Soil atmosphere: inverse relationship between O2 and CO2 O2 ~ 20% at surface to < 5% in lower horizons No O2, anaerobic (typical of wet soils) Carbon dioxide levels often 0.35 % – 10× that of air Other gases: H2O vapor (typically 100% relative humidity) In strongly reduced soils: methane (CH4), ethylene (C2H4), and hydrogen sulfide (H2S) (toxic to plants if air exchange is too slow)

74 Tendency of a substance to accept or donate electrons Oxidation-reduction potential a way to characterize aeration E h …. 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 and electron acceptors Primary electron acceptors in soils (if O2 absent): – ½NO3 – + H+ + e– → ½NO2– + ½H2O – ½MnIVO2 + H+ + e– → ½Mn2+ + H2O – Fe3+ + e– → Fe2+ – ½SO42– + 5H+ + 4e– → ½H2S + 2H2O

75 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

76 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?

77 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

78 WETLAND – LAHAN YANG AERASINYA BURUK 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.

79 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.

80 TIGA CIRI WETLANDS Diunduh 16/2/2012 Vegetation: More than 50% of the dominant species are hydrophytic plants (aerenchyma tissues typical) Hydrology: Seasonally inundated and/or saturated for consecutive days > 12.5% of growing season Hydric soils (redoximorphic features in upper horizons): Peraquic & aquic moisture regimes Gley chroma (< 1) Organic matter accumulation 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.

81 PENTINGNYA WETLANDS Diunduh 15/2/2012 Pengendalian Banjir: Temporary storage of excess water >19 million acres of wetlands have been drained in the Upper Mississippi River Valley Loss of 30 million acre-feet of storage Restoration of 15% would have reduced flood stage at St. Louis in 1993 by 2 feet The wetland system of floodplains is formed from major rivers downstream from their headwaters. The floodplains of major rivers act as natural storage reservoirs, enabling excess water to spread out over a wide area, which reduces its depth and speed. Wetlands close to the headwaters of streams and rivers can slow down rainwater runoff and spring snowmelt so that it doesn’t run straight off the land into water courses. This can help prevent sudden, damaging floods downstream.

82 Diunduh 15/2/2012 Kualiats Air – Water movement VERY slow – Sediments settle – Nutrients utilized by plant life – Effective pollution filter (agricultural and urban) Groundwater recharge Shoreline 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).

83 Diunduh 16/2/2012 Soil T-Affected Processes Plant growth rates Seed germination Root functions Microbial processes – < 5 ºC not much happens – Biological activity doubles with every 10 ºC increase Freezing and thawing – Ice lenses – Frost heaving PENTINGNYA WETLANDS Wetlands cycle both sediments and nutrients balancing terrestrial and aquatic ecosystems. A natural function of wetland vegetation is the up-take and storage of nutrients found in the surrounding soil and water. These nutrients are retained in the system until the plant dies or is harvested by animals or humans. Wetland vegetation productivity is linked to the climate, wetland type, and nutrient availability. The grasses of fertile floodplains produce the highest yield including plants such as Arundo donax(giant reed), Cyperus papyrus (papyrus), Phragmites (reed) and Typha (cattail, bulrush).

84 PENYERAPAN DAN KEHILANGAN ENERGI SURYA …. Diunduh 7/2/2012 Albedo: the fraction of incident radiation that is reflected from the land surface Aspect: how the land faces the sun – south facing vs. north facing Rain: – Summer rains cool the soil – Spring rains warm the surface but, overall, make the soil cooler and harder to warm (high specific heat of water determines the rate at which soil warms in the spring).

85 AERASI TANAH …. Diunduh 7/2/2012 Ventilation of soil allowing gases to be exchanged with atmosphere Proses pertukaran ags terjadi melalui: Mass flow: air forced in by wind or pressure Diffusion: gas moves back and forth from soil to atmosphere acc. to pressure

86 …. Diunduh 7/2/2012 Oksidasi Loss of electrons Fe +2 Fe Fe Fe+2 e-

87 …. Diunduh 7/2/2012 REDUKSI Gain of electrons Fe +3 Fe Fe Fe+2 e-

88 …. 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 NO 3 - (nitrate) Manganese Mn +2 (manganous) Mn +4 (manganic)

89 Bentuk-bentuk oksidasi dan reduksi …. Diunduh 14/2/2012 Sulfur S -2 (sulfide) …. Red SO 4 -2 (sulfate) ….. Oks Carbon CH 4 (methane) …. Red CO 2 …….Oks

90 l …. 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.

91 ethane_oxidation/ …. Diunduh 14/2/2012 REAKSI OKSIDASI electrons that could potentially be transferred to others 2FeO + 2H 2 O 2FeOOH + 2H e - Fe +2 Fe +3 H + ions formed

92 …. 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 (H 2 O) O 2 + C 6 H 12 O 6 CO 2 + H 2 O Electron donor Electron acceptor

93 …. Diunduh 14/2/2012 To determine E h Insert electrode in soil solution: –free dissolved oxygen present : E h stays same –oxygen disappears, reduction (electron gain) takes place and probe measures degree of reduction ( mv) –As organic substances are oxidized (in respiration) E h drops as sequence of reductions (electron gains) takes place.

94 Bentuk-bentuk oksidasi dan reduksi hara …. Diunduh 14/2/2012 Oxidized formReduced formEh (v) O2O2 H2OH2O NO 3 -1 N2N Mn +4 Mn Fe +3 Fe SO 4 -2 S CO 2 CH

95 …. Diunduh 14/2/2012 Organic substrate oxidized (decomposed) by various electron acceptors: O 2 NO 3 - Mn +4 Fe +3 SO 4 -2 Rates of decomposition are most rapid in presence of oxygen

96 Organic Matter Decomposition and the Formation of Humic Substances. e_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 acids Organic matter accumulates –Allows Histosol development

97 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. tml …. Diunduh 7/2/2012 AERASI TANAH - BENTUK DAN MOBILITAS HARA Soil aeration determines which forms of chemicals are present and how mobile they are  Redox colors in Poorly and Well-Aerated Soil  Nutrient elements

98 …. Diunduh 7/2/2012 BENTUK SENYAWA / ION : TANAH AERASI JELEK Reduced forms of iron and manganese Fe +2, Mn +2 Reduced iron is soluble; moves through soil, removing red, leaving gray, low chroma colors (redox depletions) Reduced manganese : hard black concretions

99 AERASI TANAH - PENYIANGAN …. 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.

100 Organic Matter Decomposition Pathways for Anaerobic Respiration. e_id=2 …. Diunduh 7/2/2012

101 Organic Matter Decomposition Pathways for Aerobic Respiration.

102 AERASI TANAH Soil aeration is one of the most important factors affecting turf health. Poor aeration can lead to root death. The black layer often found in putting greens is due to poor aeration. Aerasi tanah dapat diperbaiki dengan jalan memperbaiki struktur tanah dan pengolahan tanah. Aerasi tanah merupakan proses dimana udara di dalam tanah digantikan oleh udara dari atmosfer. Dalam tanah yang aerasinya baik, udara tanah mempunyai komposisi yang sama dengan atmosfer di atasnya. Tanah- tanah beraerasi buruk biasanya mengandung persentase CO2 yang lebih banyak dan tentunya persentase O2 yang lebih sedikit daripada atmosfer di atasnya. Tingkat aerasi sebagian besar bergantung-kepada volume dan kontinuitas pori-pori terisi udara di dalam tanah. …. Diunduh 12/2/2012

103 PEMADATAN TANAH Soil compaction occurs when forces, such as tire or foot traffic, compress the soil and alter pore structure. Bulk density increases, macropores decrease, infiltration decreases, aeration decreases. Compaction is most a problem when soils are wet. A similar problem is caused by shearing forces or puddling of soil surfaces. …. 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.

104 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

105 PENDANGIRAN TANAH Cultivation before planting is pretty easy, as long as the soil is not too wet. Cultivation after planting is the basis of an entire equipment industry. Pieces include hollow and solid tine aerifiers, water injectors, air injectors, slicers, spikers, wing blades, and Klingon disruptor beams. debrt=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.

106 I. Process of Soil Aeration A.O 2 availability in field 1.soil macroporosity (texture/structure) 2.soil water content (proportion of porosity filled with air) 3.O 2 consumption by respiring organisms (plant roots and microbes) B.Excess Moisture 1.water saturated/waterlogged: condition when all or nearly all of the soil pores are filled with H 2 O 2.adaption C.Gas exchange 1.mass flow 2.diffusion (Fig. 7.3)

107 PROSES DIFUSI GAS

108 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.

109 AERASI TANAH A.Composition 1.O 2 2.CO 2 (Fig. 7.8) 3.other gases B.Air-filled porosity 1.ideal composition 2.O 2 diffusion through water<<<<

110 KONSENTRASI CO 2 DALAM UDARA TANAH …. Diunduh 12/2/2012

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112 Other e - acceptors

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114 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

115 FAKTOR AERASI TANAH A.Drainage 1.Why are macropores important to soil aeration? B.Rates of respiration 2. What management activities can alter soil air composition? C.Subsoil vs. topsoil 3. Why do subsoils have lower O 2 concentrations than surface soils? D.Soil heterogeneity 4.How do O 2 and CO 2 concentrations change within a profile? 5.What effect does tillage have on aeration? E.Seasonal differences 6. Contrast spring vs. summer soil aeration. F.Effects of vegetation 7. What is an effect of one specific type of vegetation on soil aeration?

116 UDARA TANAH


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