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  1. BahanKajian MK. DasarIlmu Tanah KEMASAMAN TANAH pH Tanah smno.jurtnh.fpub.nop2013

  2. pH = - log (H+ ion concentration) pH = 7 neutral As pH increases… As pH decreases… Sumber: Brady and Weil, 2002

  3. Kisaran pH optimum untukberbagaijenistanaman

  4. Mo lebihtersediakalau pH naik ^

  5. Toksisitas Aluminum Toxic forms of Al are bioavailable at low pHs Aluminum toxicity is minimal above pH 5.5

  6. Bentuk-bentukKemasaman Tanah pH tanahmengukurkemasamanaktif KemasamanAktif KemasamanCadangan Brady and Weil, 2002

  7. KemasamanCadangan Kemasamancadanganmensuplaikemasamanaktif Very little lime is needed to neutralize the active acidity in soils ΔpH ΔpH Reserve acidity Active acidity Reserve acidity Active acidity Tanah dengan KTK rendah Tanah dengan KTK tinggi

  8. Setiapmuatan yang ditandaipada diagram inimencerminkan 1 centimolmuatan per kg tanah K+ - - Ca+2 - - Mg+2 - - H+ Humus H20 H20 H20 Exchangeable acidity exchangeable cations soil solution H20 H20 H20 - Clay - - Al+3 + H2O ↔ Al(OH)3 + 3H+ - + - + - K+ SO4-2 Ca+2 ApakahKejenuhanBasa?

  9. Apakah pH berhubungandengankejenuhanbasa? 100 80 60 40 20 0 Acid Saturation, %

  10. Muatan yang tergantung pH The dominant clay minerals in IL have mostly permanent charge

  11. Muatanlistrikpadasubstansihumik (danliatygaktivitasnyarendah) sangattergantung pH Muatantergantung pH Ion H+berdisosiasikalau pH tanahnaikdan re-asosiasikalau pH turun. Brady and Weil (2002)

  12. Soil acidity increases when H+ producing processes exceed H+ consuming processes. H+ consuming processes H+ producing processes

  13. Banyakproses yang menambah ion H+ketanah 1) Carbonic acid forms when carbon dioxide dissolves in water. H+ ions are released when carbonic acid dissociates: H2CO3 → HCO3- + H+ 2) Organic acids form during the decomposition of organic matter. H+ ions are released when these organic acids dissociate. 3) Sulfuric and nitric acids form during the oxidation of reduced forms of N and S (e.g., NH4+ from fertilizer, elemental S). NH4+ + O2 → NO3- + 2H+ S0 + O2 → SO4-2 + 2H+ 4) Sulfuric and nitric acids form when sulfur oxides and nitric oxides (released into the atmosphere by automobile emissions, industry smoke stacks, volcanoes, forest fires) dissolve in precipitation. H2SO4 and HNO3 are strong acids and fullydissociate in water. 5) Roots release H+ to balance internal charge when cation uptake exceeds anion uptake. VERY IMPORTANT PART OF SOIL FORMATION

  14. Banyakproses yang mengkonsumsi ion H+dalamtanah • (1) Weathering of most minerals (e.g., silicates, carbonates…) • (2) Decomposition of organic anions • (3) Reduction of oxidized forms of N, S and Fe. • (4) Roots release OH- or HCO3- to balance internal charge when anion uptake exceeds cation uptake • (5) Inner sphere adsorption of anions (especially sulfate) which displaces hydroxyl (OH-) groups

  15. Oksida-oksida C, N danS menyebabkanhujanasam Brady and Weil, 2002

  16. Sumber-sumberpenyangga pH dalamtanah Carbonates Chadwick and Chorover ( 2001)

  17. K+ H+ pH rizosfirtanamanberubahkalaumengaturkeseimbanganmuatanlistrikinternalnya. NO3- ?

  18. Manatanaman yang dipupuknitrat? Manatanaman yang dipupuk ammonium ?

  19. Masukanasammendorongpencuciankationbasa Mengapapencuciankationbasamemicukemasamantanah? Brady and Weil, 2002

  20. Siklus N released into the soil 1H+consumed 1H+consumed NH3 2 H+ yang dihasilkanselamaprosesnitrifikasidiimbangidengan 2 H+yang dikondumsiselamapembentukan NH4+danserapan NO3-olehtanaman

  21. Standard jumlahkapurygdiperlukanuntukmenetralkankemasmaan yang dihasilkanolehpupuk N. Asumsi: 1) Semua ammonium-N dikonversimenjadi nitrate-N 2) separuh nitrate tercuci.

  22. PanenbiomasatanamanberartimengambilsejumlahalkalinitasdarilahanpertanianPanenbiomasatanamanberartimengambilsejumlahalkalinitasdarilahanpertanian

  23. Lime rates should be guided by soil testing

  24. Sumbervariasidalampengukuran pH tanah 1. The soil to solution ratio used when measuring pH. 2. The salt content of the diluting solution used to achieve the desired soil to solution ratio. 3. The carbon dioxide content of the soil and solution. 4. Errors associated with standardization of the instrument used to measure pH.

  25. Mengapamengukur pH tanahdenganmenggunakanlarutangaram? Water pH > Salt pH Brady and Weil, 2002

  26. pH tanahtergantungpadametodepengukurnanya. As a result, the method of measurement should be reported whenever soil pH data is discussed.

  27. When a soil is limed, Ca+2 from the lime displaces exchangeable acidity from the soil colloids. The active acidity that is generated reacts with the carbonate ions from the lime, producing water and carbon dioxide. H+ Ca+2 soil colloid + CaCO3 soil colloid + H2O + CO2 H+

  28. “Illinois method” untukmenentukankebutuhankapur How do you know which line to use ?

  29. Memilihbahankapur yang tepat Line A: Dark colored silty clays and silty clay loams (CEC > 24) Line B: Light and medium colored silty clays and silty clay loams, dark colored silts and clay loams (CEC 15-24) Line C: Light and medium colored silt and clay loams, dark and medium colored loams, dark colored sandy loams (CEC 8-15) Line D: Light colored loams, light and medium colored sandy loams and all sands (CEC < 8) Line E: Mucks and peat (organic soils). Light colored (< 2.5% OM) Medium colored (2.5-4.5% OM) Dark colored (4.5% OM)

  30. Tidaksemuabatu-kapursamakualitasnya! Pure calcium carbonate has a calcium carbonate equivalency (CCE) of 100 and is the standard against which all liming materials are compared. A ton of material with a CCE of 90 % can neutralize 10% less acid than a ton of pure calcium carbonate. Liming materials that are finely ground, have more surface area in contact with the soil solution than coarser ground materials and thus will neutralize soil acidity more rapidly. Fineness of grind is rated according to the percentage of material that will pass through 8-, 30-, and 60-mesh screens.

  31. Reaksikapurdalamtanahmemerlukanwaktu

  32. pH tanahdanKebutuhanKapurdapatberagamdalamsuatubentanglahan pH measurements on the fly

  33. Barak P, Jobe BO, Krueger AR, Peterson LA, Laird DA 1997. Effects of long-term soil acidification due to nitrogen fertilizer inputs in Wisconsin. PLANT AND SOIL. 197(1): 61-69Agroecosystems are domesticated ecosystems intermediate between natural ecosystems and fabricated ecosystems, and occupy nearly one-third of the land areas of the earth. Chemical perturbations as a result of human activity are particularly likely in agroecosystems because of the intensity of that activity, which include nutrient inputs intended to supplement native nutrient pools and to support greater biomass production and removal. At a long-term fertility trial in South-Central Wisconsin, USA, application of ammoniacal N fertilizer resulted in significant increases in exchangeable acidity accompanied by decreases in cation exchange capacity (CEC), base saturation, and exchangeable Ca2+ and Mg2+ . Plant analysis shows that a considerable portion of the alkalinity generated by assimilation of N (and to a lesser extent by S) is sequestered in the above-ground plant parts as organic anions and is not returned to the soil if harvested. Elemental analysis of soil clays indicates a loss of 16% of the CEC. The reversibility of this change is doubtful if the changes are due to weathering of soil minerals.

  34. Permasalahankesuburantanahpadakondisi pH tanah yang ekstrim