temperatur tanah : perilaku dan efeknya bagi tanaman
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Bahan kajian untuk MK Dasar Ilmu Tanah smno.jurtnh.fpub.nop2013. TEMPERATUR TANAH : Perilaku dan Efeknya bagi Tanaman. TEMPERATUR TANAH. Temperatur atau Suhu adalah tingkat kemampuan benda dalam memberi atau menerima panas. - PowerPoint PPT PresentationTRANSCRIPT
TEMPERATUR TANAH:
Perilaku dan Efeknya bagi
Tanaman
Bahan kajian untuk MK Dasar Ilmu Tanahsmno.jurtnh.fpub.nop2013
TEMPERATUR TANAH
Temperatur atau Suhu adalah tingkat kemampuan benda dalam memberi atau
menerima panas.
Suhu seringkali juga dinyatakan sebagai energi kinetis rata-rata suatu benda yang
dinyatakan dalam derajat suhu.
Suhu juga dinyatakan sebagai ukuran energi kinetik rata-rata dari pergerakkan
molekul suatu benda. Suhu menunjukkan sangkar cuaca yang
dipergunakan untuk pengamatan suhu. Pengukuran dilakukan dengan
menggunakan thermometer air raksa dan alkohol.
Dengan thermometer air raksa pengukuran dapat dilakukan dari suhu 35o C – 350o C, hasilnya adalah cukup
bagus karena mengingat angka pengembangan air raksa pada tiap suhu
lebih merata dari alkohol, sehingga untuk pengukuran suhu udara biasanya
digunakan thermometer air raksa.
http://blkmtncommunitygarden.blogspot.com/2010/03/soil-temperature-chart-for-seed.html
Pentingnya temperatur tanah?
Temperatur tanah
Salah satu sifat fisika tanah yang sangat berpengaruh
terhadap proses-proses dalam tanah, seperti
pelapukan dan penguraian bahan organik dan bahan induk tanah, reaksi-reaksi
kimia , dll.
http://www.regional.org.au/au/asssi/supersoil2004/s15/oral/1502_walla.htm diunduh 15/2/2012
Example of soil moisture and temperature during and after freezing. (Gravimetrically determined θv was 11.8 % on day 0 and 11.3% on day 9.)
Soil moisture measurement in the Ross Sea region of Antarctica using Hydra soil moisture probes.Aaron M. Wall, Megan R. Balks, Dave I. Campbell and Ron F. Paetzold
Faktor-faktor yang mempengaruhi suhu tanah :
1. Faktor iklim / cuaca
– radiasi surya– Keawanan– Hujan– suhu udara– Angin– kelembaban
udara
The soil temperature is much less influenced by climatic changes. The graph shows the variation in temperature over a year at different depths (0, 2, 5 and 12 feet). As we can see, the temperature
fluctuation decreases with increasing depth.
Sumber: http://www.enviroair.ca/en/geothermal.html..... . diunduh 12/2/2012
Faktor-faktor yang mempengaruhi suhu tanah :2. Keadaan tanah
– tekstur tanah– kadar air tanah– kandungan bahan
organik– warna tanah– struktur tanah
(pengolahan ddan kepadatan tanah)
Depth dependence of annual range of ground temperatures in Ottawa, Canada (Williams and Gold 1976, National Research Council of Canada 2003).
Sumber: http://iopscience.iop.org/1748-9326/2/4/044001/fulltext/ diunduh 12/2/2012
Faktor-faktor yang mempengaruhi suhu tanah :
3. Kondisi topografi
– kemiringasn lereng
– arah lerreng
– tinggi permukaan tanah
– vegetasi
Definition ofthe Temperature Vegetation Dryness Index (TVDI). TVDIfor a given pixel (NDVI,Ts) is estimated as the relation between the distance ofthe pixel from the wet edge (TVDI=O) and the spån ofTs in the Ts/NDVI-spacefor the given NDVI (the difference between Ts and the dry edge (TVDI=I) and Ts at the
wet edge).SUMBER: http://www.tidsskrift.dk/visning.jsp?markup=&print=no&id=71866 Diunduh 12/2/2012)
Pentingnya temperatur tanah
1. Temperatur tanah mempengaruhi aktivitas biologi tanah---- tidak optimal apabila suhu tertentu tidak dapat dipertahankan
• Tingkat aktivitas optimum dari organisme tanah adalah suhu 18 – 30oC
• Kurang dari 10o C: menghambat perkembangan mikroba tanah dan menghambat penyerapan hara oleh akar tanaman
• Lebih dari 40oC : mikroba tanah tidak aktif, kecuali mikroorganisme tertentu (termofilik).
PENTINGNYA TEMPERATUR TANAH
2. Temperatur tanah juga menentukan reaksi kimia dan aktivitas mikroba tanah yang dapat merombak senyawa organik tertentu menjadi hara tersedia.
• Proses nitrifikasi ( temperatur optimum ± 30o C ), yaitu pada kondisi agak panas
http://info.cycadpalm.com/bid/57663/How-to-Fertilize-Cycads-Part-2 diunduh 15/2/2012
Pentingnya temperatur tanah3. Temperatur tanah juga
mempengaruhi pelapukan bahan induk tanah
4. Temperatur tanah mempengaruhi perkembangan akar, karena ada hubungannya dengan kelengasan dan aerasi tanah
5. Temperatur tanah mempengaruhi pekecambahan biji dan pertumbuhan kecambah
Effect of soil temperature on nitrate formation (adapted from Fredereick and Broadbent, 1966).
http://www.ipm.iastate.edu/ipm/icm/2001/10-22-2001/why50.html … diunduh 15/2/2012
Pentingnya temperatur tanahpertumbuhan tanaman tertentu (jenis berbeda) menghhendaki keadaan
temperatur yang cocok.
http://www.cropinfo.net/AnnualReports/2003/YNSResponsetoEnvironment03.htm.... .. Diunduh 12/2/2012
SUHU TANAH BAGI CACING
Suhu atau temperatur tanah yang ideal untuk pertumbuhan cacing tanah dan penetasan kokonnya berkisar antara 15oC –
25oC.
Suhu tanah yang lebih tinggi dari 25oC masih cocok untuk cacing tanah, tetapi harus diimbangi dengan kelembapan yang
memadai dan naungan yang cukup.
Oleh karena itu, cacing tanah biasanya ditemukan hidup dibawah pepohonan atau tumpukan bahan organik.
http://biologi.lkp.web.id/?p=604 diunduh 3/2/2012
Dimana suhu tanah diukur?
Termometer TanahUsed to take temperatures at 5 and 10 cm
depths
PVC Spacer
PVC Spacer
Kalibrasi Termometer tanah
Basically, we compare the soil thermometer to a calibration thermometer, and adjust the
soil thermometer.
First, we need to check the calibration thermometer!!
…by dipping it in an ice bath.
Checking Calibration Thermometer• Submerge thermometer in ice-water
bath
• Let sit for 10-15 minutes, stirring thermometer occasionally
• Read the thermometer. If it reads between -0.5° C and +0.5° C, the thermometer is fine.
• If the thermometer reads greater than +0.5° C, check to make sure that there is more ice than water in your ice-water bath.
• If the thermometer reads less than -0.5° C, check to make sure that there is no salt in your ice-water bath.
Kalibrasi Termometer Tamah
• Add the soil thermometer to the ice bath• Wait 2 minutes• Read both Soil Thermometer and calibration
thermometer.• If they agree to within ±2° C, the soil thermometer is
ready to use.• If not adjust the soil thermometer, using a wrench, until
it reads with ±2° C of the calibration thermometer
Kapan mengukur suhu tanah ?• Soil temperature is a weekly measurement, but
you can do it daily. • Try to do the measurement at about the same
time of day • Take data near the atmosphere station or near the
soil moisture site • Also measure soil temperature measurement
whenever a soil moisture data are taken • Seasonally (4 times a year), measure soil
temperature every few hours during the day for 2 consecutive days – provides a diurnal reading of soil temperature change– diurnal sampling in March, June, Sept. and Dec. are
preferred
Regim Temperatur Tanah ---
Regim temperatur tanah RTTT RTTMP-RTTMD RTTMP
PergelikCryikFrigid
IsofrigidBorealMesik
IsomesikTermik
IsotermikHipertermik
Isohipertermik
< 00 – 80 – 80 – 8< 8
8 – 158 – 1515 – 2215 – 22
> 22> 22
> 5< 5> 5<5>5< 5> 5< 5
Rendah> cryic
Estimasi temperatur berdasarkan ketinggian tempat (elevasi)
Di tempat-tempat yang tidak tersedia data temperatur (stasiun iklim terbatas), maka temperatur udara dapat diduga
berdasarkan ketinggian tempat (elevasi) dari atas permukaan laut. Pendugaan tersebut dengan menggunakan pendekatan
rumus dari Braak (1928) dalam Mohr et al. (1972).
Berdasarkan hasil penelitiannya di Indonesia temperatur di dataran rendah (pantai) berkisar antara 25-27ºC, dan rumus
yang dapat digunakan (rumus Braak) adalah sebagai berikut:
26,3°C - (0,01 x elevasi dalam meter x 0,6°C)
Berdasarkan penelitian Braak tersebut temperatur tanah pada kedalaman 50 cm di Indonesia lebih tinggi 3-4,5ºC, sehingga
untuk menduga temperatur tanah pada kedalaman 50 cm, maka rerata temperatur udara ditambah sekitar 3,5ºC.
Menurut Wambeke et al. (1986) temperatur tanah lebih tinggi 2,5ºC dari temperatur udara.
Hasil pendugaan temperatur dan ditambah perbedaan temperatur udara dan temperatur tanah tersebut digunakan
untuk menentukan rejim temperatur tanah seperti yang ditetapkan dalam Taksonomi Tanah
(Soil Survey Staff, 1992; 1998).
RADIASI MATAHARIPermukaan bumi merupakan penyerap utama radiasi matahari . Oleh
sebab itu permukaan bumi merupakan sumber panas bagi udara di atasnya dan bagi lapisan tanah di bawahnya.
Pada siang hari suhu permukaan tanah akan lebih tinggi dibandingkan dengan suhu pada lapisan tanah yang lebih dalam.
Permukaan tanah menyerap radiasi matahari secara langsung pada siang hari, setelah itu panas merambat ke lapisan tanah yang lebih dalam.
Sebaliknya pada malam hari permukaan tanah akan kehilangan panas terlebih dahulu, akibatnya suhu pada permukaan tanah akan lebih rendah dibandingkan dengan suhu pada lapisan yang lebih dalam. Pada malam
hari panas akan merambat dari lapisan yang lebih dalam menuju permukaan.
Sumber: STUDI DIFUSIVITAS TERMAL PADA MEDIUM TANAH MELALUI PENGUKURAN SUHU. Aries Astradhani Subgan. Natural, Oktober 2006. Vol 5. No.2
PERPINDAHAN PANAS
Proses perpindahan panas yang terjadi di dalam tanah adalah perpindahan panas secara konduksi.
Proses perpindahan panas ini terjadi karena adanya gerakan molekul dalam tanah.
Temperatur adalah suatu pernyataan tentang kinetik energi molekul benda, adanya suatu beda suhu di dalam suatu benda umumnya akan menyebabkan perpindahan energi kinetik oleh banyaknya tumbukan dari molekul-molekul yang bergerak dari
daerah yang lebih panas ke daerah sekitarnya yang lebih dingin.
Sumber: STUDI DIFUSIVITAS TERMAL PADA MEDIUM TANAH MELALUI PENGUKURAN SUHU. Aries Astradhani Subgan. Natural, Oktober 2006. Vol 5. No.2
TRANSFER PANASProses stedi (steady;) atau proses takstedi (unsteady) terjadi dalam
proses transfer panas.
Bilamana laju aliran panas dalam suatu sistem tidak berubah dengan waktu (konstan), maka suhu dititik manapun tidak berubah. Hal ini yang
dikatakan kondisi keadaan-stedi.
Dengan kondisi keadaan-stedi (steady state), kecepatan fluks-masuk pada titik manapun dari sistem manapun harus tepat sama dengan
kecepatan fluks-keluar, dan tidak dapat terjadi perubahan energi-dalam. Aliran panas dalam suatu sistem takstedi terjadi bila suhu diberbagai titik
dari sistem tersebut berubah dengan waktu.
Sumber: STUDI DIFUSIVITAS TERMAL PADA MEDIUM TANAH MELALUI PENGUKURAN SUHU. Aries Astradhani Subgan. Natural, Oktober 2006. Vol 5. No.2
Dengan adanya perubahan suhu, maka akan terjadi perubahan energi dalam.
Perubahan kandungan panas dari sebuah permukaan tanah antara permukaan Z1 = 0 dan beberapa kedalaman Z2 diberikan oleh :
AS = - (qh2 – qh1) ≈
Dimana qh positif ke arah bawah
zz
qh
Sumber: STUDI DIFUSIVITAS TERMAL PADA MEDIUM TANAH MELALUI PENGUKURAN SUHU. Aries Astradhani Subgan. Natural, Oktober 2006. Vol 5. No.2
http://www.texas-geology.com/ac_heat_pumps.html
KERAPATAN FLUX PANAS
Kerapatan fluks panas tanah positif arah bawah ketika ΔS = - (qh2 - qh1) positif, maka lebih banyak panas yang masuk di
bagian atas daripada yang meninggalkan bagian bawah lapisan tanah sehingga tanah menjadi panas.
Jika ΔS = - (qh2 - qh1) negatif, maka lebih banyak panas yang keluar daripada yang masuk ke permukaan sehingga tanah
menjadi dingin.
Sumber: STUDI DIFUSIVITAS TERMAL PADA MEDIUM TANAH MELALUI PENGUKURAN SUHU. Aries Astradhani Subgan. Natural, Oktober 2006. Vol 5. No.2
TRANSFER PANASTeori transfer panas dalam tanah telah digunakan untuk menentukan sifat-sifat termal rata-rata dari regim suhu yang diamati, juga untuk pendugaan perubahan harian dan
musiman suhu tanah. di alam, tanah yang homogen hanya terdapat pada lapisan-lapisan yang tipis, sehingga suhu tanah umumnya bukanlah fungsi sinus sederhana.
Sumber: STUDI DIFUSIVITAS TERMAL PADA MEDIUM TANAH MELALUI PENGUKURAN SUHU. Aries Astradhani Subgan. Natural, Oktober 2006. Vol 5. No.2
Amplitude of seasonal soil temperature change as a
function of depth below ground surface.
http://www.builditsolar.com/Projects/Cooling/
EarthTemperatures.htm
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0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24Waktu Pengamatan Waktu Per 30 Menit
Grafik Fungsi Fourier Suhu Tanah Bervegetasi Tiap Kedalaman
Z=0 Cm
Z=5 Cm
Z=10 Cm
Z=15 Cm
Z=20 Cm
Z=25 Cm
Suhu Tanah
(0C)
Sumber: STUDI DIFUSIVITAS TERMAL PADA MEDIUM TANAH MELALUI PENGUKURAN SUHU. Aries Astradhani Subgan. Natural, Oktober 2006. Vol 5. No.2
Grafik Fungsi Fourier Suhu Tanah Tidak Bervegetasi Tiap Kedalaman
19202122232425262728293031323334353637383940414243444546
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24Waktu Pengamatan Waktu Per 30 Menit
Z=0 Cm Z=5 Cm Z=10 Cm Z=15 Cm Z=20 Cm Z=25 Cm
Suhu Tanah
(0C)
Sumber: STUDI DIFUSIVITAS TERMAL PADA MEDIUM TANAH MELALUI PENGUKURAN SUHU. Aries Astradhani Subgan. Natural, Oktober 2006. Vol 5. No.2
TEMPERATUR TANAH
Temperatur (suhu) adalah salah satu sifat tanah yang sangat penting secara langsung mempengaruhi pertumbuhan tanaman
dan juga terhadap kelembapan, aerasi, stuktur, aktifitas mikroba, dan enzimetik, dekomposisi serasah atau sisa
tanaman dan ketersidian hara-hara tanaman.
Tenperatur tanah merupakan salah satu faktor tumbuh tanaman yang penting sebagaimana halnya air, udara dan unsur hara. Proses kehidupan bebijian, akar tanaman dan mikroba tanah
secara langsung dipengaruhi oleh temperatur tanah
Hanafiah, Kemas Ali. 2005. Dasar-dasar Ilmu Tanah. PT. Radja Grifindo. Persada. Jakarta.
FAKTOR SUHU TANAHTentang suhu tanah pengaruhnya penting sekali pada kondisi tanah itu sendiri dan pertumbuhan tanaman. Pengukuran dari suhu tanah biasanya dilakukan pada kedalaman 5 cm, 10 cm,
20 cm, 50 cm, dan 100 cm.
Faktor pengaruh suhu tanah yaitu faktor luar dan faktor dalam.
Faktor luar yaitu radiasi matahari, awan, curah hujan, angin, kelembapan udara. Faktor dalamnya yaitu faktor tanah,
struktur tanda, kadar iar tanah, kandungan bahan organik, dan warna tanah. Makin tinggi suhu maka semakin cepat
pematangan pada tanaman
Kartasapoetra, dkk. 2005. Teknologi Konservasi Tanah. Rineka jaya. Jakarta.
FLUKTUASI SUHU TANAH
Suhu tanah beraneka ragam dengan cara khas pada perhitungan harian dan musiman. Fluktasi terbesar
dipermukaan tanah dan akan berkurang dengan bertambahnya kedalaman tanah.
Kelembapan waktu musiman yang jelas terjadi, karena suhu tanah musiman lambat bantuk fluktasi suhu pada peralihan
suhu diudara atau dibawah tanah yang lebih besar. Suhu total untuk semalam tanaman mungkin terjadi pada tengah hari.
Dibawah 6 inch atau 15 inch terdapat variasi harian pada suhu tanah
Sosrodorsono. 2006. Variasi Tanah. Rineka Jaya. Bogor.
TEMPERATUR TANAH
Data temperatur tanah dapat dilihatpada Tabel 4 menunjukkan bahwa suhuharian pada permukaan tanah sangat
fluktuasi dengan pola mendekati fungsisinusoidal.
Fluktuasi temperatur permukaan tanah dipengaruhi oleh perubahan suhu atmosfir di atas permukaan tanah.
Temperatur tanah pada pagi hari relatif kecil, temperatur tanah pada pagi hari di lahan naungan cenderung lebih tinggi daripada
di areal lahan tanpa naungan.
PENGARUH IRIGASI DAN NAUNGAN TERHADAP PRODUKSI TANAMAN CABE (Capsicum annum) PADA LAHAN BERPASIR
DI PANTAI GLAGAH, YOGYAKARTAIkhwanuddin Mawardi dan Sudaryono. 2008. J. Hidrosfir Indonesia Vol. 3(1) : 41 -49
SUHU TANAH - KEDALAMAN
Pada variasi kedalaman yaitupermukaan tanah, kedalaman 10 cm, 20cm dan 30 cm, untuk temperatur tanah
dalam naungan memiliki temperatur yangtertinggi, sedangkan kedalaman 10 cmmempunyai temperatur tanah terendah.
Hal ini disebabkan pada pagi haripermukaan tanah telah menerima
pancaran radiasi matahari, tetapi transferpanas belum mencapai kedalaman 10 cm.Temperatur tanah pada kedalaman 30 cmlebih tinggi dibandingkan kedalaman 10
cm dan 20 cm, karena masih menyimpansebagian energi radiasi matahari yang
diterima sehari sebelumnya.
SUHU TANAH – SIANG AHRI
Temperatur tanah pada siang hari, jikadilihat pada tabel tersebut dapat dilihatbahwa temperatur tanah pada sing harilebih panas daripada temperatur tanah
pada pagi hari.
Hal ini dapat terjadi karena pada siang hari radiasi yang diterima oleh permukaan tanah lebih besar.
Temperatur tanah pada siang hari di areal lahan dengan memakai naungan lebih tinggi daripada
lahan yang tidak memakai naungan.
SUHU TANAH - LAPISAN TANAH
Berdasarkan variasi kedalaman, makapermukaan tanah mempunyai temperaturtanah tertinggi, sedangkan kedalaman 30
cm mempunyai temperatur tanahterendah.
Jadi pada siang hari temperaturpermukaan tanah akan lebih tinggi jikadibandingkan temperatur pada lapisan
tanah yang lebih dalam.
Hal ini disebabkan karena permukaan tanah menyerap radiasi matahari secara
langsung, baru kemudian panasdirambatkan ke lapisan tanah yang lebih
dalam secara konduksi.
SUHU TANAH - KEDALAMAN
Temperatur tanah pada sore hari akanlebih kecil dibandingkan dengan
temperatur tanah pada pagi dan sianghari. Temperatur tanah dalam naungan
lebih tinggi daripada di areal lahan tanpanaungan.
Berdasarkan variasi kedalaman,pada kedalaman 10 cm mempunyai
temperatur tanah tertinggi sedangkankedalaman 30 cm memiliki temperatur
tanah terendah.
Tingginya temperaturtanah pada kedalaman 10 cm dapat
disebabkan oleh akumulasi transfer panasdari permukaan atau tingginya aktivitas
mikroorganisme dalam merombak bahanorganik pada lapisan tersebut.
FLUKTUASI SUHU TANAH
Bila dilihat dari hasil pengamatanselama 3 bulan, baik itu pagi, siang dan
sore hari terlihat temperatur tanahberfluktuasi, dan cenderung lebih stabil
seiring dengan bertmbahnya umurtanaman.
Fluktuasi temperatur padapermukaan tanah lebih besar daripada
kedalaman 10 cm, 20 cm dan 30 cm. Halini tidak terlepas dari pengaruh intensitas
radiasi matahari yang diterima olehpermukaan tanah.
Jadi intensitas radiasi matahari yang berfluktuasi akan menyebabkan temperatur tanah juga
berfluktuasi.
Soil temperatures over three days at different depths.Sumber: http://www.learner.org/jnorth/tm/tulips/SoilTempBack.html..... diunduh
12/2/2012
Suhu Tanah• Relation of Soil & Air Temp
– Net heat absorbed by the Earth = heat lost in form of longwave radiation
– Photoperiod – affected by latitude
– Soil temp can change by soil depth & time of day• Takes significant air temp changes to change soil temp
deeper than 12” (& more than just daily range)
Suhu Tanah
• Factors Affecting Soil Temp– How much heat reaches the soil surface
• Tutupan muka tanah• Mulsa plastik• Sudut datang radiasi matahari• Arah Muka Lereng• Tanah
Suhu Tanah– What happens to the heat in the soil
(dissipation)• Amount of heat needed to change soil temp
= heat capacity– Greatly affected by soil water content
» How?– Thermal conductivity – increases w/ soil-
water content increasing, decreases as air-filled pores increase• Moist soils resist temp change, but conduct
heat readily• Dry soils change temp faster, but conduct
heat poorly– What does this mean for the soil, which is better?
Suhu Tanah• Living w/ Existing Temps
– Maximizing seed germination & growth• Wheat – 40 to 50° F• Corn – 50 to 85° F
– When using anhydrous• Apply when soil temp @ 4” is 50° F or less
– Mereduksi kehilangan N
– Freeze/thaw• May cause heaving – resulting in death of shallow
rooted crops
Suhu tanah– Responsible for bringing stones to the surface in
fields
• Modifying Temp Effects– If you have crops that are feasible/profitable to do so– Clear plastic surface covers
• Increases soil temp faster
– Clear plastic mulches• Can speed growth & maturity of sweet corn &
strawberries
CIRI THERMAL TANAH
The thermal properties of soil are a component of soil physics that has found important uses in engineering, climatology and agriculture.
These properties influence how energy is partitioned in the soil profile. While related to soil temperature, it is more accurately associated with the transfer of heat throughout the soil, by radiation, conduction and
convection.
The main soil thermal properties are:Volumetric heat capacity, SI Units: J.m-3∙K-1
Thermal conductivity, SI Units: W.m-1∙K-1
Thermal diffusivity , SI Units: m2∙s-1
. http://en.wikipedia.org/wiki/Soil_thermal_properties ….. Diunduh 4/2/2012
SUHU TANAH dipengartuhi oleh:
Latitude; seasonnet radiation at the surface
soil texture ; moisture contentground cover
surface weather conditions
. http://en.wikipedia.org/wiki/Soil_thermal_properties ….. Diunduh 4/2/2012
CIRI-CIRI THERMAL TANAH
So, in order to determine the skin temperature of the soil, it is important to understand how heat is transferred upward and and downward through the soil. The important heat transfer mechanism in this problem is conduction. Then, the ground
heat flux at any depth in the soil can be given as:
where kg is the thermal diffusivity of the soil.
http://apollo.lsc.vsc.edu/classes/met455/notes/section6/2.html .... diunduh 5/2/2012
Using the Second Law of Thermodynamics, show that a prognostic equation for the soil temperature can be given by:
(2)
where Cg is the soil heat capacity (Cg = soil density, r, times the soil specific heat, c)
combining (2) with (1) yields:
(3)
where vg = kg/Cg = soil thermal diffusivity.Given proper boundary conditions, (3) can be solved to find the soil temperature at
different levels as a function of time. With appropriate boundary conditions, solutions to (3) show that soil temperature decreases exponentially with depth and that the phase of the temperature changes with depth as well, consistent with the figures shown above.
http://apollo.lsc.vsc.edu/classes/met455/notes/section6/2.html .... diunduh 5/2/2012
Typical values of the mass density, specific heat, thermal conductivity and thermal diffusivity for different materials
http://apollo.lsc.vsc.edu/classes/met455/notes/section6/2.html ..... Diunduh 6/2/2012
MATERIAL CONDITION MASS DENSITY (r) (kg m-3 x 103)
SPECIFIC HEAT (c) (J kg-1 K-1 x 103)
THERMAL CONDUCTIVITY (kg)
(W m-2 K-1)
THERMAL DIFFUSIVITY (vg) (m2 s-1 x10-6)
Air 20 Deg C, Still 0.0012 1.01 0.025 20.5
Water 20 Deg C, Still 1.00 4.19 0.57 0.14
Ice 0 Deg C, Pure 0.92 2.10 2.24 1.16
Snow Fresh 0.10 2.09 0.08 0.38
Snow Old 0.48 2.09 0.42 0.05
Sandy Soil Fresh 1.60 0.80 0.30 0.24
Clay Soil Dry 1.60 0.89 0.25 0.18
Peat Soil Dry 0.30 1.92 0.06 0.10
Rock Solid 2.70 0.75 2.90 1.43
FLUKTUASI SUHU TANAH
Soil temperature variations decrease exponentially with depth. only small fluctuations are observed at depths of about 1
meter. much smaller fluctuations are observed at depths of 10 meters.
http://apollo.lsc.vsc.edu/classes/met455/notes/section6/2.html ..... Diunduh 6/2/2012
KAPASITAS PANAS VOLUMETRIK
Volumetric heat capacity (VHC), also termed volume-specific heat capacity, describes the ability of a given volume
of a substance to store internal energy while undergoing a given temperature change, but without undergoing a phase
change.
It is different from specific heat capacity in that the VHC depends on the volume of the material, while the specific heat is based on the mass of the material (or occasionally the molar
quantity of the material).
If given a specific heat value of a substance, one can convert it to the VHC by multiplying the specific heat by the density of
the substance.http://en.wikipedia.org/wiki/Volumetric_heat_capacity … diunduh 5/2/2012
KAPASITAS PANAS
Dulong and Petit predicted in 1818 that the product of solid substance density and specific heat capacity (ρcp) would be constant for all solids.
This amounted to a prediction that volumetric heat capacity in solids would be constant.
This quantity was proportional to the heat capacity per atomic weight (or per molar mass), which suggested that it is the heat capacity per atom (not per unit of volume) which is closest to being a constant in solids.
Eventually (see the discussion in heat capacity) it has become clear that heat capacities per particle for all substances in all states are the same, to within a factor of two, so long as temperatures are not in the cryogenic
range. For very cold temperatures, heat capacities fall drastically and eventually
approach zero as temperature approaches zero.http://en.wikipedia.org/wiki/Volumetric_heat_capacity … diunduh 5/2/2012
KAPASITAS PANAS VOLUMETRIK.
The heat capacity on a volumetric basis in solid materials at room temperatures and above varies more widely, from about 1.2 to 4.5
MJ/m³K, but this is mostly due to differences in the physical size of atoms.
If all atoms were the same size, molar and volumetric heat capacity would differ by a single constant reflecting ratios of the atomic-molar-volume of materials (their atomic density), plus an additional number
between 1 and 2 which reflects degrees of freedom for the atoms compositing the substance at various temperatures.
For liquids, the volumetric heat capacity is narrower: in the range 1.3 to 1.9 MJ/M³k.
This reflects the modest loss of degrees of freedom for particles in liquids as compared with solids.http://en.wikipedia.org/wiki/Volumetric_heat_capacity … diunduh 5/2/2012
KAPASITAS PANAS VOLUMETRIK
Since the bulk density of a solid chemical element is strongly related to its molar mass (usually about 3 R per mole, as noted above), there exists
noticeable inverse correlation between a solid’s density and its specific heat capacity on a per-mass basis. This is due to a very approximate tendency of
atoms of most elements to be about the same size, despite much wider variations in density and atomic weight. These two factors (constancy of atomic
volume and constancy of mole-specific heat capacity) result in a good correlation between the volume of any given solid chemical element and its
total heat capacity. Another way of stating this, is that the volume-specific heat capacity (volumetric heat capacity) of solid elements is roughly a constant. The molar volume of solid elements is very roughly constant, and (even more reliably) so also is the molar heat capacity for most solid substances. These two factors determine the volumetric heat capacity, which as a bulk property
may be striking in consistency.
For example, the element uranium is a metal which has a density almost 36 times that of the metal lithium, but uranium's volumetric heat capacity is only
about 1.2 times larger than lithium's.http://en.wikipedia.org/wiki/Volumetric_heat_capacity … diunduh 5/2/2012
.KONDUKTIVITAS THERMAL
Thermal conductivity, k, is the property of a material's ability to conduct heat. It appears primarily in Fourier's Law for heat
conduction.Heat transfer across materials of high thermal conductivity occurs at a higher rate than across materials of low thermal
conductivity. Correspondingly materials of high thermal conductivity are widely used in heat sink applications and materials of low thermal conductivity are used as thermal
insulation.
Thermal conductivity of materials is temperature dependent. The reciprocal of thermal conductivity is thermal resistivity.
http://en.wikipedia.org/wiki/Volumetric_heat_capacity … diunduh 5/2/2012
SUHU TANAH - MUSIMAN
Soil temperature varies from month to month as a function of incident solar radiation, rainfall, seasonal swings in overlying air temperature, local vegetation cover, type of
soil, and depth in the earth. Due to the much higher heat capacity of soil relative to air and the thermal insulation provided by vegetation and surface soil layers, seasonal changes in soil temperature
deep in the ground are much less than and lag significantly behind seasonal changes in overlying air temperature.
Thus in spring, the soil naturally warms more slowly and to a lesser extent than the air, and by summer, it has become cooler than the overlying air and is a natural sink for
removing heat from a building. Likewise in autumn, the soil cools more slowly and to a lesser extent than the air, and by winter it is warmer than the overlying air and a natural
source for adding heat to a building.
At soil depths greater than 30 feet below the surface, the soil temperature is relatively constant, and corresponds roughly to the water temperature measured in groundwater
wells 30 to 50 feet deep. This is referred to as the “mean earth temperature.”
http://en.wikipedia.org/wiki/Volumetric_heat_capacity … diunduh 5/2/2012
SUHU TANAH – FLUKTUASI MUSIMAN
The amplitude of seasonal changes in soil temperature on either side of the mean earth temperature depends on the type
of soil and depth below the ground surface. In Virginia the amplitude of soil temperature change at the
ground surface is typically in the range of 20-25ºF, depending on the extent and type of vegetation cover.
At depths greater than about 30 feet below the surface, however, the soil temperature remains relatively constant
throughout the year, as shown in Figure 3, below.
http://en.wikipedia.org/wiki/Volumetric_heat_capacity … diunduh 5/2/2012
SUHU TANAH – KEDALAMAN PROFIL.
. http://www.geo4va.vt.edu/A1/A1.htm …. Diunduh 5/2/2012
SUHU TANAH - VARIASI HORISONTAL
Vertical closed-loop earth heat exchangers are installed in boreholes 200 to 300 feet deep, where seasonal changes in soil temperature are
completely damped out. Well-based open-loop systems also extend to this depth or deeper. These ground loop configurations are thus exposed
to a constant year-round temperature. On the other hand, horizontal-loop, spiral-loop, and horizontal direct-
expansion (DX) loops are installed in trenches that usually are less than 10 feet deep. For these types of ground loops, it is important to
accurately know the expected seasonal changes in the surrounding soil temperature.
The extra cost of installing such systems in deeper trenches may be outweighed by the gain in thermal performance, since deeper soils have
less pronounced seasonal temperature changes and are thus closer to room temperature, which reduces the work load of the heat pump units.
. http://www.geo4va.vt.edu/A1/A1.htm …. Diunduh 5/2/2012
SUHU TANAH – KEDALAMAN
Deeper soils not only experience less extreme seasonal variations in temperature, but the changes that do occur lag farther behind those of
shallower soils. This shifts the soil temperature profile later in the year, such that it more closely matches the demand for heating and cooling.
The maximum soil temperature occurs in late August (when cooling demand is high) at a depth of 5 feet below the ground surface, but occurs in late October (after the heating season has begun) at a depth of 12 feet below the surface.
Thus a deeper ground loop installation would lower the annual operating cost for electrical energy to run the heat pumps, and over the life of a GHP system,
these accumulated savings may more than offset the higher capital cost of burying the ground loop more deeply.
In order to determine the optimal depth of burial, it is important to accurately know how the seasonal change in soil temperature varies with depth, which is
mainly determined by the soil's thermal properties.
. http://www.geo4va.vt.edu/A1/A1.htm …. Diunduh 5/2/2012
. Seasonal soil temperature change as a function of depth below ground surface for an average moist soil.
. http://www.geo4va.vt.edu/A1/A1.htm …. Diunduh 5/2/2012
CIRI-CIRI THERMAL TANAH
Heat capacity (also known as specific heat) indicates the ability of a substance to store heat energy; the greater its heat capacity, the more heat
it can gain (or lose) per unit rise (or fall) in temperature.
The heat capacity of dry soil is about 0.20 BTU per pound per ºF of temperature change, which is only one-fifth the heat capacity of water.
Therefore, moist or saturated soils have greater heat capacities, typically in the range of 0.23 to 0.25 BTU/lb/ºF.
The light dry soils experience greater seasonal temperature swings at a given depth than wet soils.
This is because their lower heat capacity causes their temperature to rise or fall more than wet soils for a given amount of heat energy gained in
the spring or lost in the fall. . http://www.geo4va.vt.edu/A1/A1.htm …. Diunduh 5/2/2012
KONDUKTIVITAS THERMAL
(KT) Thermal conductivity is another soil property that must be known in order to design a closed-loop or direct expansion GHP system. This indicates
the rate at which heat will be transferred between the ground loop and the surrounding soil for a given temperature gradient.
The thermal conductivity of the soil and rock is the critical value that determines the length of pipe required, which in turn affects the installation cost as well as the energy requirements for pumping working fluid through the ground loop.
KT - TANAH BERAGAM DENGAN TEKSTURNYA.
Heat transfer capability tends to increase as soil texture becomes increasingly fine, with loam mixtures having an intermediate value between sand and clay.
As also shown in this figure, the thermal conductivity of any soil greatly improves if the soil is saturated with water. This effect is much greater for sandy soils than for clay or silt, since coarse soils are more porous and therefore hold
more water when wet.
. http://www.geo4va.vt.edu/A1/A1.htm …. Diunduh 5/2/2012
Konduktivitas thermal berbgaai tipe tekstur tanah.
. http://www.geo4va.vt.edu/A1/A1.htm …. Diunduh 5/2/2012
KONDUKTIVITAS PANAS
The soil thermal conductivity has a significant impact on the size of the earth-coupled heat exchanger. Thus in sandy soils for example the required length of the ground loop could be as low as 200 feet per system ton if the soil is saturated with water, or as high
as 300 feet per ton if the soil is dry.
Soil thermal conductivity is of even greater importance to DX systems and designers might consider the deployment of a “soaker hose” for horizontal DX ground loops in
dry areas or if the project site is higher than the sounding terrain.
The maps presented in the next section below enable rough estimates of soil properties for regional screening purposes, but any sort of detailed feasbility assessment or design
study should engage a contractor for in-situ soil thermal conductivity testing.
The range in ground loop lengths over the typcial range of soil thermal conductivities is 200 to 300 feet per system ton, which translates into a 30-50% difference in required
land area, and a 10-20% difference in total system capital cost.
In-situ conductivity testing minimizes the uncertainty in estimating this key thermal property and avoids undersizing or oversizing the ground loop. . http://www.geo4va.vt.edu/A1/A1.htm …. Diunduh 5/2/2012
Thermal conductivity influence on number of boreholes and total length of the earth-coupled heat exchanger per 10 tons of load for a vertical
closed-loop GHP system.
. http://www.geo4va.vt.edu/A1/A1.htm …. Diunduh 5/2/2012
SUHU TANAH
Amplitude: Amplitude is a parameter characterizing the annual variation of soil temperature around an average value. If the variation in temperature within a day is
averaged out over manyyears, the annual amplitude is one-half the difference between this annual averaged
maximum and annual averaged minimum temperatures within a year.
Damping depth: Damping depth is a constant characterizing the decrease in amplitude with an increase in distance from the soil surface. It is defined as (2Dh/w)1/2, where D
h is the thermal diffusivity and w is the frequency of a temperature fluctuation. For annual fluctuation w =2 p /365 d-1.
Thermal diffusivity: Thermal diffusivity is the change in temperature produced in a unit volume by the quantity of heat flowing through the volume in unit time under a unit temperature gradient. It can be calculated from thermal conductivity and volumetric
heat capacity. Time lag: Time lag is the number of days from an arbitrary starting date to the
occurrence of the minimum temperature in a year.
. http://www.geo4va.vt.edu/A1/A1.htm …. Diunduh 5/2/2012
SUHU TANAH - WAKTU DAN KEDALAMAN
Soil temperature fluctuates annually and daily affected mainly by variations in air temperature and solar radiation.
The annual variation of daily average soil temperature at different depths can be estimated using a sinusoidal function (Hillel, 1982;
Marshall and Holmes, 1988; Wu and Nofziger, 1999).
This program estimates daily soil temperatures and displays these values as functions of time or depth for user defined input
parameters.
http://soilphysics.okstate.edu/software/SoilTemperature/document.pdf …. DIUNDUH 5/2/2012
MODEL VARIASI SUHU TANAH
The annual variation of daily average soil temperature at different depths is described with the
following sinusoidal function ( Hillel, 1982):
where T(z,t) is the soil temperature at time t (d) and depth z (m), T a is the average soil temperature (oC), A0 is the annual amplitude of the surface soil temperature (oC), d is the damping depth (m) of annual
fluctuation and t0 is the time lag (days) from an arbitrary starting date (taken as January 1 in this software) to the occurrence of the minimum
temperature in a year.The damping depth is given by d = (2D h/w )1/2, where Dh is the
thermal diffusivity and w = 2 p /365 d-1 .
http://soilphysics.okstate.edu/software/SoilTemperature/document.pdf …. DIUNDUH 5/2/2012
MODEL SINUS VARIASI SUHU TANAH
Assumptions and Simplifications
The sinusoidal temperature model was derived by solving the following partial differential equation ( Hillel, 1982 ; Marshall and Holmes, 1988):
where T(z,t) is the soil temperature at time t and depth z and Dh is the thermal diffusivity.
http://soilphysics.okstate.edu/software/SoilTemperature/document.pdf …. DIUNDUH 5/2/2012
VARIASI SUHU TANAH
The following assumptions are employed in the derivation of the temperature model:
1. A sinusoidal temperature variation at the soil surface z = 0. That is
where Ta is the average soil temperature, A0 is the amplitude of the annual temperature function, t0 a time lag from an arbitrary starting date (selected as January 1 in this software) to the occurrence of the minimum
temperature in a year.2. At infinite depth, the soil temperature is constant and is equal to the
average soil temperature.3. The thermal diffusivity is constant throughout the soil profile and
throughout the year.
http://soilphysics.okstate.edu/software/SoilTemperature/document.pdf …. DIUNDUH 5/2/2012
Measured mean and predicted soil temperatures at four depths based on measured soil surface temperatures.
http://soilphysics.okstate.edu/software/SoilTemperature/document.pdf …. DIUNDUH 5/2/2012
Suhu tanah pada berbagai kedalaman: Diprediksi berdasarkan suhu udara.
http://soilphysics.okstate.edu/software/SoilTemperature/document.pdf …. DIUNDUH 5/2/2012
Konduktivitas dan difusivitas thermal tanah: Dipengaruhi kadar air, kadaungan liat, dan bobot isi tanah.
http://soilphysics.okstate.edu/software/SoilTemperature/document.pdf …. DIUNDUH 5/2/2012
Volumetric heat capacity for three bulk densities for soils whose thermal conductivity and diffusivity.
http://www.usyd.edu.au/agric/web04/Temperature%20Waves_final.htm
SUHU TANAH - PENANAMANWhether you’re planting seeds or targeting weeds, it’s important to check your
soil temperature before beginning.
Even the best-planned garden project can fall flat if temperatures are not appropriate for the occasion! For example, did you know that you should:
Plant spring bulbs when the soil temperature drops below 60° F.Apply crabgrass control in spring, when soil temperatures reach 55° F for 4-5
days in a row.Plant cool-season grass seed once soil temperatures are in the 50s F.
Give your new shrubs time to grow roots before soil temperatures fall below 40° F.Be very careful when starting vegetable seeds, since germination temperature is
vital to the seeds’ success and every vegetable is different.
http://www.usyd.edu.au/agric/web04/Temperature%20Waves_final.htm. http://www.dannylipford.com/how-to-measure-soil-temperature-for-planting/
SUHU TANAH - PENANAMAN
http://www.usyd.edu.au/agric/web04/Temperature%20Waves_final.htm. http://www.dannylipford.com/how-to-measure-soil-temperature-for-planting/
Soil temperature plays an important role in soil chemical reactions and biological interactions, particularly nutrient and fertilizer transformations, solute transport, gas
exchange and the transformation and transport of contaminants (Buchan 2001).Soil temperature varies in response to exchange processes that take place primarily
through the soil surface. These effects are propagated into the soil profile by transport processes and are influenced by such things as the specific heat capacity, thermal
conductivity and thermal diffusivity. Soil temperature can vary greatly throughout the day with increasing and decreasing solar radiation. Soil temperatures also vary greatly with depth from the surface, as well as with differences in soil cover (mulch) and soil water content. The thermal
properties of a soil have been found to be indicative of the soil water content. Water is a better thermal conductor than air. The thermal conductivity of soil increases with
increasing water contents (Fredlund, 1992).
Buchan, G.D., (2001) Soil Temperature Regime, in Smith, K.A., and Mullins, C.E. (Eds). Soil and Environmental Analysis: Physical Methods 2nd Ed. 2001. Marcel Dekker. pp, 539-594.Fredlund, D.G. (1992). Background, Theory, and Research Related to the Use of Thermal Conductivity Sensors for Matric Suction Measurement. Soil Science Society of America. Advances in Measurement of Soil Physical Properties: Bringing Theory into Practice, 249-261.
TERMOMETER TANAHYou can purchase a simple soil thermometer at your local garden center for just a few dollars.
The most economical ones are glass bulb thermometers with a strong metal point. However, any thermometer will do, as long as it measures temperatures down to freezing (medical thermometers
usually don’t go low enough).
http://www.ipm.iastate.edu/ipm/icm/2001/10-22-2001/why50.html … diuduh 15/2/2012
Influence of soil temperature on nitrification.Ammonium sulfate nitrification after 24 days. Soils held at either constant temperature (80, 60, or 40°F) for 24
days, or the temperature varied (between 80, 60, and 40°F sequences) by 8- or 12-day intervals over the 24 days.
Adapted from Chandra, P. 1962. Note on the effect of shifting temperatures on nitrification in a loam soil. Can. J. Soil Sci. 42:314-315.
Temperature Sequence % NitrificationContinuous at 80°F for 24 days 10012 Days at 80°F-12 days at 40°F 96
8 Days at 80°F-8 days at 60°F-8 days at 40°F 74
12 Days at 40°F-12 days at 80°F 62Continuous at 60°F for 24 days 59
8 Days at 60°F-8 days at 80°F-8 days at 40°F 56
8 Days at 40°F-8 days at 60°F-8 days at 80°F 45
Continuous at 40°F for 24 days 29
BAGAIMANA MENGUKUR SUHU TANAH?.
Measure the Right Depth: If you are planting seeds or new plants, take your measurement at the recommended planting depth. If you’re measuring for a
mixed garden, check at least 5-6 inches deep.
Make a Pilot Hole: Use a screwdriver to make a pilot hole so that you don’t break your thermometer by pushing it into hard soil.
Follow Directions: Refer to your thermometer package for specific instructions. With most glass bulb thermometers, make sure it is firmly touching
the soil, and allow a few minutes for the temperature to register.
Provide Shade: If the sun is bright, shade the thermometer with your hand to keep the reading accurate.
Multiple Measurements: Take a reading in the morning and late afternoon, then average the two numbers. If you’re seeding a lawn, take readings on all four sides of your house, since some areas warm more quickly than others.
Check Reading: To double-check, refer to these handy Soil Temperature Maps from Greencast for a comparison with your soil reading.
SUHU TANAH – PERKECAMBAHAN BENIH
The soil temperature for planting vegetables should be:
40° F or warmer: Lettuce, kale, peas, spinach.50° F or warmer: Onions, leeks, turnips, Swiss
chard.60° F or warmer: Broccoli, cabbage, cauliflower,
carrots, beans, beets.70° F or warmer: Tomatoes, squash, corn,
cucumbers, melons, peppers.
The seed germination temperature is often much warmer than the plant’s growing temperature. Once established, many veggies can handle
much cooler air temperatures as long as the soil is warm enough.
To get a head start on spring planting, plant seeds indoors or use plastic row covers to warm
the soil more quickly.
Temperature has a large influence on rate of seed water uptake, speed of germination, and rate of plant emergence. As temperature increases, both the rate of water uptake and speed of germination increase and time to emergence decreases for winter wheat
The effect of soil temperature on speed of germination and emergence of Norstar winter wheat (from Lafond and Fowler, 1989).
http://www.usask.ca/agriculture/plantsci/winter_cereals/Winter_wheat/CHAPT11/cvchpt11.php
. Soil temperature and vegetable seed germination
.http://www.waldeneffect.org/blog/Soil_temperature_and_vegetable_seed_germination/Diunduh 5/2/2012
Vegetable Minimum temp. (degrees F) Optimum temp. (degrees F)
Beans 60 60-85
Cabbage 40 45-95
Carrots 40 45-85
Corn 50 60-95
Cucumbers 60 60-95
Lettuce 35 40-80
Muskmelons 60 75-95
Okra 60 70-95
Onions 35 50-95
Parsley 40 50-85
Peas 40 40-75
Peppers 60 65-95
Pumpkins 60 70-90
Spinach 35 45-75
Squash 60 70-95
Swiss chard 40 50-85
Tomatoes 50 70-95
Turnips 40 60-105
Watermelons 60 70-95
SUHU TANAH - TANAMAN
The temperature of a soil is important as it affects how fast plants can grow. Soil temperature also
affects how quickly plants take up water and nutrients. Clay soils are cold, wet soils.
Germination and seedling growth is usually slow.Because sandy soils don't contain much water but lots of air, they warm up quickly. They are useful
for growing early crops.
Soil temperature affects the speed of chemical reactions. Warm temperatures speed up reactions and colder ones slow them down. Soil temperature affects the breakdown of parent material and how fast micro-organisms work. Both are important in
adding and returning nutrients to the soil. Soil temperature is influenced by the climate of
the area and the season of the year.
http://www.correspondence.school.nz/departments/horticulture/ht106_p7.html. ....
Diunduh 5/2/2012Effect of soil temperature and water potential on emergence time of Norstar winter wheat (from Lafond and Fowler,
1989).http://www.usask.ca/agriculture/plantsci/winter_cereals/Winter_wheat/CHAPT11/cvchpt11.php
SUHU TANAH - POSISI LERENG
The slope of the land and the direction that it
faces directly affects the temperature of a
soil.
Sun will fall on north-facing land during the day in both summer
and winter.
http://www.correspondence.school.nz/departments/horticulture/ht106_p7.htmlDiunduh 5/2/2012
SUHU TANAH – KEDALAMAN TANAHThe deeper you go down in a soil profile the less the soil temperature
will fluctuate
http://www.correspondence.school.nz/departments/horticulture/ht106_p7.htmlDiunduh 5/2/2012
Soil is a good insulator. It can take a while for the soil at the bottom of a profile to heat up, but it will also take a longer time for it to lose the
heat that is stored there.
SUHU TANAH DAN AKTIVITAS
BIOLOGIS TANAHSoil temperature affects the speed of
plant growth and soil processes.Soil temperature is influenced by:
climate, season, aspect, water levels, soil colour, plant cover and soil
depth.The temperature in a soil will
determine the speed of chemical and biological activity.
Clay soils take a long time to warm up but are also slower to cool down. The temperature in a sandy soil can change rapidly. Wet soils also take
longer to warm up.http://www.correspondence.school.nz/
departments/horticulture/ht106_p7.htmlDiunduh 5/2/2012
Amplitude of seasonal soil temperature change as a function of depth below ground surface.http://www.builditsolar.com/Projects/Cooling/EarthTemperatures.htm diunduh 15/2/2012
SUHU-TANAH OPTIMUM BAGI TANAMAN
Corn requires a soil temperature of 50° F to germinate and grow
and soybeans require a soil temperature of 54° F.
Temperatures below the optimum will cause seeds to sit dormant and become more
vulnerable to diseases, insects, and animal predators.
Crops should be planted when soil temperatures are optimal and within the target
dates for the region. Keep in mind these dates are based on the average year and the use of short or long
relative maturity corn products will affect these target dates.
Planting into cold and/or wet soils can lead to numerous problems.
http://munsonhybrids.com/tidbits/Plant%20Corn%20and%20Soybean%20By%20Soil%20Temperature%20and%20Conditions%20Not%20According%20To%20The%20Calendar%20-%20IA.pdf ….. Diunduh 5/2/2012
Aqua ammonia incubated in soil at controlled temperature.http://www.ipm.iastate.edu/ipm/icm/2001/10-22-2001/why50.html
SUHU TANAH DAN PERTUMBUHAN BIBIT
Soil temperature is more important than air temperature when planting seeds or seedlings. You can have in the spring a warm spell of temps in the 70’s while the soil temp is still in the 40’s. Every vegetable has a preferred soil
temp for seeds or transplants. A soil thermometer is essential for determining the proper planting time. Planting too early, before the soil has had time to
warm up, can lead to seed rot, slowed germination, poor growth and disease.
Use the following guide for minimum soil temperatures for seeds and transplants:
60o F - tomatoes, cucumbers, snap beans65o F - sweet corn, lima beans, mustard greens70o F - peppers, watermelons, squash, southern peas75o F - okra, cantaloupe, sweet potatoes
http://yardener.com/YardenersPlantHelper/FoodGardening/BasicsofVegetableGardening/SoilBuildingandManagementintheVegetableGarden/SoilTemperatureIsImportant
Diunduh 5/2/2012
Soil Temperature Germination Ranges for Select Vegetables
TEMP (° F) PLANT
35–75 spinach (optimum 68)
35–80 lettuce and most salad greens (at more than 80, germination rate drops 50%)
40–75 peas (optimum 75)
45–85 cabbage, kale, broccoli, collards (germinate well at 85, seedlings prefer 45–65)
45–95 radishes (optimum 85)
50–85 onions (optimum 75)
50–85 beets, Swiss chard (optimum 85)
60–85 beans, snap and dry (optimum 80)
60–95 corn (optimum 95)
60–95 peppers (optimum 85)
65–100 cucumbers, melons, squash (optimum 80–95)
65–82 tomatoes (optimum 80)
70–85 beans, lima (optimum 85)
From: Market News, March 1995.
http://yardener.com/YardenersPlantHelper/FoodGardening/BasicsofVegetableGardening/SoilBuildingandManagementintheVegetableGarden/SoilTemperatureIsImportant
Diuinduh 5/2/2012
Daftar Pustaka
deVries, D. A., 1963. Thermal Properties of Soils. In W.R. van Wijk (ed.) Physics of Plant Environment. North-Holland Publishing Company, Amsterdam.
de Vries, D. A. 1975. Heat Transfer in Soils. In D.A. de Vries and N.H. Afgan (ed.) Heat and Mass Transfer in the Biosphere. Pp.5-28. Scripta Book Co., Washington, DC.
Farouki, O.T. 1986. Thermal Properties of Soils. Series on rock and soil mechanics. Vol. 11. Trans Tech Publ., Clausthal-Zellerfeld, Germany.
Hillel, D. 1982. Introduction to soil physics. Academic Press, San Diego, CA.
Marshall, T. J. and J. W. Holmes 1988. Soil Physics. 2nd ed. Cambridge Univ. Press, New York.
Wu, J. and D. L. Nofziger 1999. Incorporating temperature effects on pesticide degradation into a management model. J. Environ. Qual. 28:92-100.