MK. DASAR ILMU TANAH BAHAN ORGANIK TANAH Oleh : Soemarno JURUSAN TANAH FPUB NOP. 2013

1. MK. DASAR ILMU TANAH BAHAN ORGANIK TANAH Oleh: Soemarno JURUSAN TANAH FPUB NOP. 2013

2. SIKLUS KARBON Tanaman CO2 Hewan Pupuk Kandang Reaksi dalam Tanah Aktivitas Mikroba CO2 Kehilangan drainage CO2, senyawa karbonat dari K, Ca, Mg, dll.

3. PemerangkapanKarbon • Tanah menangkapkarbondanmenyimpandalambentuk BOT danminerqalkarbonat • Sekitar 75% daricadangankarbondidaratanberupa BOT • Penurunancadangan BOT disebabkan: • Mineralisasi BOT • Erositanah • Pencuciankedalamtanahdan groundwater.

4. PenangkapanKarbonoleh Tanah dapatditingkatkandengancara: • Mengubahpraktekpertanian : • No-till agriculture or organic agriculture • Limited used of N fertilizer (C released during N fertilizer manufacture) • Limited irrigation (fossil fuels burned to power irrigation) • Restorasi (Pemulihan )Tanah

5. BAHAN ORGANIK TANAH KANDUNGAN , JENIS-JENIS, KARAKTERISTIKNYA

6. BENTUK-BENTUK KARBON DALAM TANAH BAHAN ORGANIK TANAH

7. SUSUNAN JARINGAN TUMBUHAN Air 75% Padatan 25% Karbon 11% Oksigen 10% Hidrogen 22% Abu 2%

8. SUSUNAN BAHAN TUMBUHAN YG DITAMBAHKAN KE TANAH AIR 75% Padatan 25%. Gula & Pati (1-5% ) Hemiselulose 10-30% Selulose 20-50% SUSUNAN UNSUR Hidrat Arang 60% Protein 10% Lignin 20-30% Karbon 44% Hidrogen 8% Abu 8% Oksigen 40% Lemak, lilin, tanin 1-8%.

9. BAHAN ORGANIK TANAH BO)T mencakupsemuakomponenorganikdaritanah: • Residusegar • BO yang sedangmengalamidekomposisi • BO yang stabil • Organismehidup

10. RESIDU SEGAR • Hingga 15% dari BO beruparesidusegar (biasanya <10) • Terdiriatasgugurandedaunan • Dapatdikenaliberagamtipeseresahtumbuhan

11. BO yang sedang mengalami Dekomposisi • Biomasatanamanditransformasikandarisatusenyawaorganikmenjadisenyawaorganiklainnyaolehorganismetanah • Organismemenghasilkanbahan-sisa, hasilsampingdansel-seltubuhnya • Senyawa-senyawa yang dilepaskansebagailimbahdarisatuorganismedapatmenjadimakananbagiorganismelainnya.

12. PERUBAHAN BAHAN ORGANIK YG DITAMBAHKAN KE TANAH I. Senyawadalamjaringantumbuhansegar SukarDilapukMudahdilapuk Lignin Selulose MinyakZatpati LemakGula Resin,dllProtein,dll II. Hasilintermedierdekomposisi SenyawatahanlapukSenyawatidaktahanlapuk Resin Asam amino LilinAmida MinyakdanlemakAlkohol Lignin,dllAldehide, dll III. HasilpelapukandantahanlapukHasilakhirygsederhana Humus: komplekskoloidal CO2 dan air dariligno-protein Nitrat Sulfat Fosfat, SenyawaCa,dll.

13. KOMPOSISI BAHAN ORGANIK • Soil microorganisms and fauna make up a relatively small portion of total soil organic matter (1-8%). • Functions as an important catalyst for transformations of N and other nutrients • Majority of soil organic matter is contained in the nonliving component that includes plant, animal and microbial debris and soil humus. • Cellulose generally accounts for the largest proportion of fresh organic material • decays rapidly • need N for decay • Lignin decomposes slowly • nutrients bound in lignin forms are not available for plant growth • lignin is insoluble in hot water and neutral organic solvents, but it is soluble in alkali solutions • seldom find calcareous soils with high organic matter. • polysaccharides decompose rapidly in soils and serve as an immediate source of C for microorganisms.

14. Parameter BIOMASA TithoniadiversifoliaTephrosiacandida Kadar air, % 70.2 62.1 N-total, % 2.1 1.7 P-total, % 0.3 0.1 C-total, % 38.5 33.9 C/N 19 21.1 C/P 128 305 Lignin, % 9.8 12.1 Polifenol, % 3.3 5.1 K, % 2.1 1.7 Ca, % 1.3 1.2 Mg, % 0.6 0.2 Asam-asamorganik, g/kg: Sitrat 32 86 Oksalat 11 30 Suksinat 48 0 Asetat 17 16 Malat 775 15 Butirat 49 0 Propionat 31 0 Phtalat 20 19 Benzoat 69 56 Salisilat 0 12 Galat 0 0 Sumber: Supriyadi, 2002.

15. APLIKASI BAHAN ORGANIK THD KANDUNGAN ASAM ORGANIK DLM TANAH , setelah 30 hari Aplikasi BO KonsentrasiasamdlmtanahAndisol (ppm): SitratOksalatSuksinatAsetatMalatButirat Total T. candida 20 0 0 15 9.1 11 55 T. diversifolia21 47 7.8 16 11 0 103 Campuran 13 15 3.6 7.2 26 5.9 70 Sumber: Supriyadi, 2002

16. BAHAN ORGANIK TANAH • Soil organic matter = • all living organisms (microorganisms, earthworms, etc), • fresh residues (old plant roots, crop residues, recently added manures), • well-decomposed residues (humus). • The SOM content of agricultural topsoil is usually in the range of 1 to 6%. • This amount is the result of all additions and losses of SOM that have occurred over the years. • Non-cultivated soils will have SOM ranges between 3-10% Citizen Science – Kansas State

17. BAHAN ORGANIK TANAH BOT bersifat labile • it can decline rapidly if the soil environment changes and renewable • it can be replenished by inputs of organic material to the soil. Labil = tidakstabil, mudahmengalamiperubahansecarakimia, fisikaataubiologis.

18. BOT = BahanOrganik Tanah • BOT = Humus • Kandungannya: • ~0 - 5% padakebanyakantanah • Hingga 100% padatanahorganik (Histosol) • Lebihtinggikandungannyapadatanah-tanahlembab • Lebihrendahkandungannyapadatanahj-tanahkering • Pengolahantanahdapatmengurangi BOT • Luaspermukaannyadan KTK sangatbesar • Kehilangan C dan N

19. Komposisi BOT • Mayoritas: ligninsdan proteins • Also: hemicellulose, cellulose, ether and alcohol soluble compounds • “nonhumic” substances = “juicy” carbon that is quickly digested • (carbohydrates, proteins, peptides, amino acids, fats, waxes, low MW acids) • Kebanyakan BOT tidaklarut air

20. Definisi Cellulose Lignin = a practically indigestible compound which, along with cellulose, is a major component of the cell wall of certain plant materials, such as wood, hulls, straws, etc. Hemicellulose: A carbohydrate resembling cellulose but more soluble; found in the cell walls of plants.

21. SIFAT & CIRI BOT • Voids can trap • Water • Minerals • Other organic molecules • Hydrophobicity/hydrophilicity • Reactivity • H-bonding, chelation of metals

22. Fig 3.8

23. GugusFungsional & MuatanListrik • PZC ~ 3 (pH of zero charge) • Up to 80% of CEC in soils is due to SOM • Acid functional groups • Carbonyls pKa < 5 • Quinones also pKa < 5 • Phenols pKa < 8 • SOM constitutes most of the buffering capacity of soils 55% of SOM CEC? 30% of SOM CEC?

24. PROFIL TANAH Lapisantanah-atas (topsoil) mengandunglebihbanyakbahanorganikdibandingkandenganlapisandibawahnya (subsoil). Sumber: ag.arizona.edu/pubs/garden/mg/so...ils.html

25. Organic Matter Biomass (living organisms) CO2 Detritus (Plant Debris) (identifiable dead tissue) degradation Fungi Earthworms Bacteria Soil Humus (nonliving, nontissue decay products) Humin (insoluble) Humic Acid (insoluble in acid) Fulvic Acid (soluble)

26. CADANGAN BOT MenekanPenyakit Agregasitanah Suplaihara BOT Aktif Dekomposisi BOT Stabil KTK Mikro-agregasi BOT Total

27. DEGRADASI BOT: SIKLUS HARA Biomass Biomasa Detritur (seresahTumbuhan) Detritus (Plant Debris) Nutrient Incorporation Penyerapan Hara Pelepasan Hara Nutrient Release Humus Tanah Soil Humus

28. HUMUS Gugusfungsionalreaktif: karboksil, hidroksil, fenolik Kapasitaspertukarankation(anion) sangatbesar Kapasitaspenyimpanan air sangatbesar Membantuagregasitanah

29. BAHAN ORGANIK TANAH CARA MENGUKURNYA

30. Bagaimana mengukur BOT? SOM is usually measured in the laboratory as organic carbon, Soil organic matter is estimated to contain 50% organic carbon (varies from 40 to 70%) with the rest of the SOM comprising of other elements (eg, 5% N, 0.5% P and 0.5% S). A conversion to SOM from a given organic carbon analysis requires that the organic carbon content be multiplied by a factor of 2.00(1.00/0.50). Thus, 2% SOM is about 1 % organic carbon. Testing for Soil Organic Carbon UF/IFAS Extension Soil Testing Laboratory

31. Analisissubstansihumikdalamtanah. Scheme for the isolation of humic substances from soil [Adapted from Stevenson (1994)]; *California Department of Food and Agriculture (CDFA) testing process end point Diunduhdarisumber: http://oceanagrollc.com/standard-humic-acid-testing-protocols-a-review/ …… 26/10/2012

32. ANALISIS BAHAN ORHANIK TANAH Diunduhdarisumber: …… 26/10/2012

33. INDIKATOR BOT . The content of organic matter of mineral horizons can be estimated from the Munsellcolour of a dry and/or moist soil, taking the textural class into account. This estimation is based on the assumption that the soil colour (value) is due to a mixture of dark coloured organic substances and light coloured minerals. This estimate does not work very well in strongly colouredsubsoils. It tends to overestimate organic matter content in soils of dry regions, and to underestimate the organic matter content in some tropical soils. Therefore, the organic matter values should always be locally checked as they only provide a rough estimate. Diunduhdarisumber: ftp://ftp.fao.org/agl/agll/docs/guidel_soil_descr.pdf …… 27/10/2012

34. Estimation of organic matter content based on Munsell soil colour. Sand . Note: If chroma is 3.5–6, add 0.5 to value; if chroma is > 6, add 1.0 to value. Source: Adapted from Schlichting, Blume and Stahr, 1995.

35. Steps in the cycling of soil C and the formation of soil organic matter and humus. Diunduhdarisumber: http://www.soils.umn.edu/academics/classes/soil5611/content/OrganicMatter/ …… 27/10/2012

36. General flow of the sequential SOM fractionation procedure. Diunduhdarisumber: http://www.sciencedirect.com/science/article/pii/S0146638002000128 …… 27/10/2012

37. BAHAN ORGANIK TANAH FUNGSINYA

38. Komponen-komponendariSistemManajemen Tanah-Berkelanjutan Sumber: www.agnet.org/library/eb/473/

39. Hubunganantara Pembangunan BerkelanjutandenganManajemen Tanah Berkelanjutan(Redrawn from Dumanski 1997) Sumber: www.agnet.org/library/eb/473/

40. Sumber: www.agnet.org/library/eb/473/

41. Fungsi BOT Fungsi & Peranan Bahan Organik Tanah (Soil Organic Matter)

42. Fungsi Humus • holds water and nutrients; • sticks together & helps establish and maintain a strong crumb structure & thus reduce soil erosion • provides some nutrients (N & P) as it is slowly decayed by microbial activity, • Buffers effects of pesticides • humus decomposes at the rate of 2.5% per year • Creates good soil “ Tilth” • Coates the sand, silt, clay particles making them dark and the darker the color, the greater the amount of soil humus present. Humus = High Medium Low

43. BOT menjagaSifatOlah Tanah • Membantuinfiltrasi air hujandanudarakedalamtanah • Membantumenahan air • Mengurangierositanah

44. “If your soil clods can't pass the water test, change your management practices. It will help your bottom line as well as the soil.” – Ray Weil – Univ of Maryland BOT = Kesehatan Tanah • Measuring SOM is one step in assessing overall soil quality or soil health - • measuring various key attributes of soil organic matter quantity and quality will give an indication of the health of the soil. • Or Look at the state of the soil organisms in the soil. • Or look at how well the soil “Holds Together”. Simple clod test: Healthy soil, at left, holds together in water, while poor soil falls apart.

45. PenggunaanKualitas Tanah • 1) Match use and management of land to soil capability, because improper use of a soil can damage it and the ecosystem. • 2) Establish a baseline understanding about soil quality so that we can recognize changes as they develop. • 3) Use baselines to determine if soil quality is deteriorating, stable, or improving. Kualitastanahmenjadiindikatordarikesehatanekosistem. NatureWatch

46. Kualitas Tanah http://www.directseed.org/soil_quality.htm • Soil quality is the capacity of soils within landscapes to sustain biological productivity, maintain environmental quality, and promote plant and animal health. • Protecting soil quality like protecting air quality and water quality should be fundamental goal of our Nation’s Environmental Policy Poor Good http://www.nrsl.umd.edu/research/NRSLResearchAreaInfo.cfm?ID=14

47. Cornell researcher George Abawi describes soil health strategies at an Onion Council field day in Wayne County, N.Y.Photo by Carol R. MacNeil. KESEHATAN TANAH • Soil Health is the change in Soil Quality over time due to human use and management or to natural events. • Descriptive terms for Soil Health • Organic Matter - high • Crop appearance = green, healthy,lush • erosion – Soil will not erode • earthworms – numerous • infiltration – fast, no ponding • Compaction - minimal In Vernon and surrounding counties are the largest concentration of organic farmers in Wisconsin.

48. Kontribusi Biota Tanah padaDekomposisi BOT Sumber: www.ipm.msu.edu/new-ag/issues06/7-26.htm

49. PerubahanKandunganBahanOrganik Tanah (jangkapanjang) padaberbagaikondisipengelolaantanah Sumber: www.agnet.org/library/eb/473/

50. Soil processes influence carbon sequestration and transport. The dynamics of carbon transformations and transport in soil are complex and can result in sequestration in the soil as organic matter or in groundwater as dissolved carbonates, increased emissions of CO2 to the atmosphere, or export of carbon in various forms into aquatic systems (DOE, 1999). Sumber: www.climatescience.gov/Library/s...hap7.htm