Sumber: www.environment.ualberta.ca/SoilsERM/lecture6/Lecture6.ppt‎ pH -TANAH & REAKSI TANAH.

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1 Sumber: www.environment.ualberta.ca/SoilsERM/lecture6/Lecture6.ppt‎ pH -TANAH & REAKSI TANAH

2 Reaksi Tanah 1.Soil reaction is the degree of acidity or alkalinity of a soil, usually expressed as a pH value. 2.Soil pH = -log [H + ] 3.Soil pH is an indicator of physical, chemical and biological properties in soil. 4.Soil pH is also related to the cations present on the exchange complex. Sumber: www.environment.ualberta.ca/SoilsERM/lecture6/Lecture6.ppt‎

3 Nilai pH beberapa material Milk of magnesia: ~10.5 Bicarbonate of soda:~8.3 Pure water: 7.0 Milk: ~6.8 Natural rain: 5 to 6 Beer/coffee: ~4 Lemon Juice: ~2 Sumber: www.environment.ualberta.ca/SoilsERM/lecture6/Lecture6.ppt‎

4 Deskripsi untuk kisaran pH tanah Sumber: www.environment.ualberta.ca/SoilsERM/lecture6/Lecture6.ppt‎

5 Tanah mempunyai ciri yang khas Credit: Pedosphere.comPedosphere.com Dark Gray Luvisol Orthic Humo-Ferric Podzol Orthic Black Chernozem Sumber: www.environment.ualberta.ca/SoilsERM/lecture6/Lecture6.ppt‎

6 pH Tanah vs. Komposisi Kation 1.Total cation exchange capacity (TCEC) is a function of quantity of clays, organic matter and iron and aluminum oxides. 2.Tipe Liat ternyata sangat penting pengaruhnya. Sumber: www.environment.ualberta.ca/SoilsERM/lecture6/Lecture6.ppt‎

7 1.Base cations (Ca ++, Mg ++, K +, Na + ) concentration decreases as soil becomes more acidic (pH decreases) 2.Kejenuhan basa berkaitan erat dengan pH tanah Sumber: www.environment.ualberta.ca/SoilsERM/lecture6/Lecture6.ppt‎ pH Tanah vs. Komposisi Kation

8 Persen Kejenuhan Basa (KB) u Basic cations: Ca ++, Mg ++, Na +, K + u Acidic cations: Al +++, H + u Percent base saturation: A measure of the proportion of basic cations occupying the exchange sites of a soil Sumber: www.environment.ualberta.ca/SoilsERM/lecture6/Lecture6.ppt‎

9 Formula Cation exchange capacity is the sum of all cations on the exchange complex % Base saturation =  (Ca ++, Mg ++, K +, Na + ) x 100 Cation Exchange Capacity Sumber: www.environment.ualberta.ca/SoilsERM/lecture6/Lecture6.ppt‎

10 Impact of soil pH on net charge of noncrystalline aluminum oxide. At low pH, H ions become bound to Al and Fe oxides Credit: Pedosphere.comPedosphere.com Sumber: www.environment.ualberta.ca/SoilsERM/lecture6/Lecture6.ppt‎

11 pH Tanah vs. Kation pada Kompleks Pertukaran (Brady and Weil, 1996) Sumber: www.environment.ualberta.ca/SoilsERM/lecture6/Lecture6.ppt‎

12 Pelarutan Al(OH) 3 Amorf Al(OH) 3 + H +  Al(OH) 2 + + H 2 O Al(OH) 2 + + H +  Al(OH) ++ + H 2 O Al(OH) ++ + H +  Al +++ + H 2 O The equilibrium reactions result in buffering of soil Sumber: www.environment.ualberta.ca/SoilsERM/lecture6/Lecture6.ppt‎

13 Mekanisme Penyangga (Buffering) 1.Oxidation of pyrite and reduced S minerals; dissolution of minerals: pH 2 to 4 2.Aluminum compounds: pH 4.0 to 5.5 3.Pertukaran Kation : pH 5.5 to 6.8 4.Organic matter and minerals: pH 6.8 to 7.2 5.Karbonat dari Ca dan Mg : pH 7.2 to 8.5 6.Na + tukar; pelarutan Na-karbonat padatan : pH 8.5 to 10.5 Sumber: www.environment.ualberta.ca/SoilsERM/lecture6/Lecture6.ppt‎

14 Tipe Kemasaman Tanah 1.Kemasaman Aktif (Active acidity): Aktivitas kation H+ dalam larutan tanah 2.Kemasaman Cadangan (Reserve acidity): The acidity that is associated with the exchange complex. It is neutralized by lime or other alkaline material Sumber: www.environment.ualberta.ca/SoilsERM/lecture6/Lecture6.ppt‎

15 Clay surface Bulk solution - - - - - - - - - - - - - - - - + + + + + + + + + + + + + + + + + + + Hydrogen is part of the crystal lattice, and can be present as an exchangeable cation and in the soil bulk solution Sumber: www.environment.ualberta.ca/SoilsERM/lecture6/Lecture6.ppt‎ Klasifikasi Kemasaman Tanah

16 1.Ketersediaan hara sangat berhubungan erat dengan kelarutannya pada berbagai nilai pH 2.At extreme pH values, solubility of some nutrients increases tremendously, leading to toxicity of plants Sumber: www.environment.ualberta.ca/SoilsERM/lecture6/Lecture6.ppt‎ Ketersediaan Hara

17 Use of ammonium-based fertilizers (NH 4 )SO 4 + 4O 2  2HNO 3 + H 2 SO 4 + 2H 2 O Deposisi Asam Nitric (HNO 3 ) + Sulfuric (H 2 SO 4 ) acids Sumber: www.environment.ualberta.ca/SoilsERM/lecture6/Lecture6.ppt‎ Pengasaman Tanah

18 Drainage of some coastal wetlands leads to the oxidation of pyrite (FeS 2 ), iron sulfide (FeS) and elemental S and formation of sulfuric acid Sumber: www.environment.ualberta.ca/SoilsERM/lecture6/Lecture6.ppt‎

19 Influence of Soil Moisture on Soil Solution Chemistry and Concentrations of Minerals in the Calcicoles Phleum phleoides and Veronica spicata Grown on a Limestone Soil APARNA MISRA and GERMUND TYLER Sumber: Annals of Botany 84: 401±410, 1999. Veronica spicata dan Phleum phleoides adalah tanaman calcicole, terutama terjadi pada tanah netral atau alkali. Eksperimen 16 minggu dilakukan di rumah kaca untuk mengelusidasi pengaruh tingkat kelembaban tanah thd kimia larutan tanah, dan konsentrasi biomassa dan penyerapan hara oleh tanaman. Tujuh tingkat kelembaban tanah, sesuai dengan 35 ± 85 % kapasitas menahan air ( WHC ) dari tanah diuji. Konsentrasi larutan tanah HCO3, P dan Mn, dan pH meningkat, sedangkan konsentrasi Ca, Mg, dan Zn menurun dengan meningkatkan kelembaban tanah. Konsentrasi K yang tertinggi di 50 ± 70 % WHC. Konsentrasi dan jumlah P, Zn dan Mn dalam dua spesies berhubungan dengan konsentrasi larutan tanah ; hara ini kelarutannya rendah dan ketersediaannya rendah pada tanah berkapur. Konsentrasi hara dalam biomassa lebih dipengaruhi oleh kelembaban tanah untuk V. spicata daripada P. phleoides. Hal ini menunjukkan bahwa P. phleoides lebih mampu mengendalikan serapan hara, sedangkan V. spicata sensitif terhadap variasi kelembaban tanah. Hal ini menyimpulkan bahwa variasi rejim kelembaban tanah sangat mempengaruhi konsentrasi hara larutan tanah berkapur dan serapan hara oleh tanaman.

20 The effect of soil water content, soil temperature, soil pH-value and the root mass on soil CO2 efflux – A modified model Sascha Reth, Markus Reichstein & Eva Falge. Sumber: Plant and Soil (2005) 268: 21–33 Untuk mengukur efek suhu tanah ( Tsoil ), dan kadar air tanah relatif ( RSWC ) thd respirasi tanah, maka dilakukan pengukuran CO2 tanah di lapangan dan di ruang iklim percobaan. Pengaruh suhu tanah thd emisi CO2 sangat signifikan pd semua penggunaan lahan, kecuali untuk lapangan terbuka dengan hujan terus menerus. Suhu tanah berpengaruh yang signifikan, persentase ragam yang dapat dijelaskan oleh suhu tanah berkisar 13-46 % di lapangan dan 35- 66 % di ruang percobaan. Perubahan kelembaban tanah mempengaruhi pelepasan CO2 pada tanah padang rumput di lapangan dan ruang percobaan ( 14-34 % ragam), sedangkan di lahan gundul dan tanah hutan tidak ada efek yang terlihat. Variasi spasial emisi CO2 tanah di lapangan berkorelasi secara signifikan dengan pH tanah dan massa akar halus, hal ini dapat menjelaskan hingga 24 % dan 31 % dari ragam. Model regresi non - linear dikembangkan untuk menggambarkan pelepasan CO2 tanah sebagai fungsi dari suhu tanah, kelembaban tanah, pH tanah dan biomasa akar. Dengan model ini kita dapat menjelaskan 60 % dari variabilitas emisi CO2 tanah dari semua individu pengukuran ruang dan lapangan. Model mengestimasi aliran CO2 secara berlebihan selama dan dalam waktu empat jam dari peristiwa hujan terakhir. Sebaliknya, setelah lebih dari 72 jam tanpa hujan ternyata estimasi model underestimated. Antara empat dan 72 jam setelah curah hujan, model regresi emisi CO2 tanah menjelaskan sampai dengan 91 % ragam.

21 Soil pH and Mineral Nutrition of Vitis vinifera Varieties. Sumber: http://www.fruit.cornell.edu/grape/pool/nutrition.html Pada tanah-tanah yang pHnya rendah, ion Al+++ mendominasi kation. Kalau pH tanah mendekati 4.5, Al-tukar mulai berkurang dan pada pH lebih dari 6 hanya sedikit sekali ion Al+++ yang tersedia bagi tanaman.

22 .pH dan Toksisitas Cu Cu menjadi lebih tersedia pada kondisi pH rendah. Toksisitas Cu biasanya berkaitan dnegan aplikasi fungisida Cu ke tanah masam. Oleh karena itu untuk mengendalikan gangguan penyakit tidak harus tergantung pada fungisida Cu. Sumber: http://www.fruit.cornell.edu/grape/pool/nutrition.html

23 .pH Tanah Sumber: http://www.swac.umn.edu/classes/soil2125/doc/s12ch1.htm pH is defined as the negative logarithm of the hydrogen ion (H+) concentration. When water ionizes to H+ and OH- (a neutral solution), both H+ and OH- ions are in equal concentrations of 0.0000001 moles per liter. That is a very small concentration. HOH H+ + OH- [H+] = [OH-] = 1 x 10 -7 moles/liter. The H+ ion and OH- concentrations in water are very small. The pH scale has been devised for conveniently expressing these small concentrations by expressing pH = Log 1/[H+]

24 .pH Tanah Sumber: http://www.swac.umn.edu/classes/soil2125/doc/s12ch1.htm When the hydrogen concentration isgreater, such as 0.0001 moles per liter, the pH is 4; when it is smaller, such as 0.00000001, the pH is 8. One thing to remember is that when the pH changes from one unit to another, the change in the hydrogen ion concentration is a ten-fold change, not just one. So a pH of 5 is ten times more acid than a pH of 6 and 100 times more acid than a pH of 7.

25 .pH Tanah Sumber: http://www.swac.umn.edu/classes/soil2125/doc/s12ch1.htm (5) uptake of positive ions by plant roots and the resulting release of H+ by the root to balance internal charge. 1.pH is < 4.0=indicates that the soil contains free acids probably as a result of sulfide oxidation 2.pH is < 5.5=indicates that the soil's exchange complex is dominated by Al 3.pH is < 7.8=soil pH is controlled by a range of factors 4.pH is > 7.8=indicates that the soil contains CaCO 3 Sources of H+ ions in the soil : 1.Dissociation of carbonic acid (H 2 CO 3 ), which forms readily in soils when CO 2 is present;--- H 2 CO 3 - ---> CO 2 + H + +HCO 3 - 2.Asam organik formed during the decomposition of organic matter; 3.Pembakaran batubara in electrical power plants releases sulfur to the atmosphere which is added to soils during precipitation as sulfuric acid, and fertilizers containing sulfur, which adds H+ ; 4.Konversi NH 4+ menjadi NO 3- melepaskan H+ selama siklus N atau ketika pemupukan nitrogen.

26 .pH Tanah Sumber: http://www.swac.umn.edu/classes/soil2125/doc/s12ch1.htm Tanah-tanah cenderung menjadi lebih masam karena: 1.Air Hujan mencuci kation basa (calcium, magnesium, potassium dan sodium); 2.CO2 dari dekomposisi BOT dan respirasi akar yang larut dalam air- tanah membentuk larutan asam lemah; 3.Penyerapan kation by plant roots and the resulting release of H+ by the root to balance internal charge; 4.Pembentukan asam kuat organik dan anorganik, such as nitric and sulfuric acid, from decaying organic matter and oxidation of ammonium and sulfur fertilizers. Strongly acid soils are usually the result of the action of these strong organic and inorganic acids.

27 .pH Tanah Pertanian Sumber: Hardy DH, Tucker MR, Stokes CE. 2014. Crop fertilization based on North Carolina soil tests. Raleigh (NC): North Carolina Department of Agriculture and Consumer Services, Agronomic Division. Circular No. 1.

28 Efek pH Tanah thd Ketersediaan Hara Sumber: http://www.summitfertz.com.au/agronomy_soil_pH.html