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Sumber : classes.uleth.ca/200801/geog3080a/ SOILS %20PART%20V%202008. ppt ‎

KEMASAMAN TANAH & Permasalahannya. Sumber : classes.uleth.ca/200801/geog3080a/ SOILS %20PART%20V%202008. ppt ‎. Soil Acidity: Causes and Impacts. Sumber : classes.uleth.ca/200801/geog3080a/ SOILS %20PART%20V%202008. ppt ‎.

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Sumber : classes.uleth.ca/200801/geog3080a/ SOILS %20PART%20V%202008. ppt ‎

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  1. KEMASAMAN TANAH & Permasalahannya Sumber: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20V%202008.ppt‎

  2. Soil Acidity: Causes and Impacts Sumber: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20V%202008.ppt‎

  3. Sumber: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20V%202008.ppt‎

  4. Sumber: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20V%202008.ppt‎

  5. Sumber: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20V%202008.ppt‎

  6. Proses-prosesPengasaman Tanah • AsamKarbonat • Carbon dioxide gas from soil air dissolves in water • Root respiration and soil decomposition provide extra CO2 • CO2 + H2O  H2CO3  HCO3- + H+ • Asam-asamdari Metabolism Biologis • Microbes break down organic matter, producing organic • acids such as citric acid, carboxylic acids and phenolic acids • RCH2OH… + O2 + H2O  RCOOH  RCOO- + H+ • AkumulasiBahanOrganik • (i) Loss of cations by leaching due to soluble humic • complexes combining with non-acid nutrient cations (eg. Ca2+) • (ii) Organic matter is a source of H+ ions Sumber: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20V%202008.ppt‎

  7. Proses-prosesPengasaman Tanah • Oksidasi Nitrogen (Nitrification) • Nitrogen memasukitanahsebagai NH4+ • Diubahmenjadiasamnitrat . • NH4+ + 2O2 H2O + H+ + H+ + NO3- • OksidasiSulphur • Asam-asamdalam air hujan • H2SO4 SO42- + 2H+ • HNO3  NO3- + H+ • Plant Uptake of Cations • Plants exude H+ ions or take up anions (eg. SO42-) to • balance off cation uptake Sumber: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20V%202008.ppt‎

  8. Toksisitas Al. Kation H+yang dijerappadapermukaanliatdapatmerusakstruktur mineral danmelepaskanAl3+dalamprosesnya Aluminiumsangattoksikbagikebanyakanjenistanaman Al memacuhidrolisis H2O Al bergabungdnegan OH-, meninggalkan H+dalamlarutantanah Tolerant plants secrete organic acids into the soil around the root. Organic acids such as (eg. malate or citrate) are able to chelate the Al that is in the soil solution near the root tip. Al that is bound to organic acids cannot enter the plant root. Sumber: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20V%202008.ppt‎

  9. Sumber: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20V%202008.ppt‎

  10. Acids are neutralized in soils with available bases Canadian Shield severely affected in central and eastern Canada Sumber: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20V%202008.ppt‎

  11. H+ + HSO3- sun  H2O H2SO4 2H+ + SO42- SO3 SO2 O2 2O2 2H2O 4NO2 2HNO3 + 2HNO2 4NO 2N20 + O2 H+ + NO3- Sumber: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20V%202008.ppt‎

  12. KepekaanterhadapPengasaman • Weathering of non-acid cations from minerals • An example is the weathering of calcium from silicates • Ca-silicate + 2H+ H4SiO4 + Ca2+ • Soil maintains its alkalinity if the release of cations from • weathering minerals exceeds leaching losses • Tanah-tanahmasamberkembangpadakondisi: • (i) Lingkungandengancurahhujantinggi • (ii) Bahanindukmiskin Ca, Mg, K , Na • (iii) where there is a high degree of biological • activity, resulting in H2CO3 formation Sumber: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20V%202008.ppt‎

  13. Efek pH tanah Terhadap KTK • KTK meningkatdengan pH karena: • Binding and release of • H+ ions on pH- • dependent charge • sites • (ii) Hydrolysis reactions • involving Al Sumber: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20V%202008.ppt‎

  14. PersenKejenuhanBasa (KB) = cmol of exchangeable Ca2+ + Mg2+ + K+ + Na+ cmolc of CEC = 100 – persenkejenuhanasam. Note: Percent acid saturation, though less often cited, is determined by cmolc Al3+ & H+ ions divided by cmolc of CEC. This is actually more meaningful, because Ca, Mg, K and Na ions are not true bases! Sumber: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20V%202008.ppt‎

  15. Proses-prosesPenyanggadalamtanah • Soils with high clay or organic content tend to have the highest buffering capacity • Why? Importance of exchangeable and residual acidity • ContohProsesPenyangga: • Aluminium hydrolysis (in very acid soils) • Al(OH)2+ + H2O  Al(OH)3 + H+ • Adding more H+ ions will drive the reaction to the left. Sumber: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20V%202008.ppt‎

  16. Proses-prosesPenyanggadalamtanah Sumber: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20V%202008.ppt‎

  17. Proses-prosesPenyanggadalamtanah • Protonation and deprotonation of organic matter • H+ ions dissociate when a base is added, preventing • pH from rising as much as expected. • CEC increases as the H+ ions are removed, increasing • the negative charges • pH-dependent charge sites in clays • Again, adding a base dissociates H+ ions from hydroxyl • groups and oxygen atoms • (iv) Cation exchange • As H+ ions are added, most end up attracted to negative • charge sites so that pH changes less than expected. If a • base is added, they are replaced by H+ ions or Al ions • from exchange sites. (most effective when pH>6). • Carbonate dissolution and precipitation (Eq. 9.18) Sumber: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20V%202008.ppt‎

  18. PENGAPURAN Liming Lime reacts with CO2 and H2O, to produce bicarbonate (HCO3-) Example: CO3- + 2H+ CO2 + H2O CaMg(CO3)2 + 2H2O + 2CO2  Ca2+ + 2HCO3- + Mg2+ + 2HCO3- • Bicarbonate is reactive with exchangeable and • residual soil acidity • Ca2+ and Mg2+replace H+ and Al3+ on clay colloids Sumber: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20V%202008.ppt‎

  19. Proses-proses yang mempengaruhi pH tanah Sumber: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20V%202008.ppt‎

  20. Sumber: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20V%202008.ppt‎

  21. EfekPengapuranterhadap pH tanah Sumber: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20V%202008.ppt‎

  22. Efek pH tanahterhadapkandungan Hara danMikroba Tanah Sumber: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20V%202008.ppt‎

  23. Penentuan pH tanah • MetodeZatPewarna • Certain organic compounds change colour in • response to pH • Drops of dye solution can be placed on white • spot plate (in contact with soil) • MetodePotentiometrik • Difference between H+ ion activity in soil suspension and glass electrode gives pH Sumber: classes.uleth.ca/200801/geog3080a/SOILS%20PART%20V%202008.ppt‎

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