PENGELOLAAN BAHAN ORGANIK

TANAH

Bahan Kajian MK. Dasar Ilmu Tanah

smno.jurtnh.fpub.nop2013

BO yang diaplikasikan ke tanah

…. Diunduh dari sumber: http://www.soils.wisc.edu/courses/SS325/organic.htm….. 26/10/2012

EFEK BO PADA AGREGASI TANAH

…. Diunduh dari sumber: http://www.sciencedirect.com/science/article/pii/S0065211303820060……….. 26/10/2012

Bacterial cells with a coat of extracellular polysaccharides (EPS) are enveloped by clay particles. The pore space where clays and bacteria interact, bounded by silt- and sand-

size particles, is relatively enriched in organic matter including EPS

residues. Fungal hyphae are attached to the outside surface of an aggregate. At normal soil pH conditions, the cell

has a net negative surface charge. Most clay particles adhere to the cell

surface by bridging through polyvalent cations, represented by Mn+

(a) although some may be attached directly by electrostatic interactions, either in face-to-face (b), or edge-to-

face (c) association. (Sumber: Theng and Orchard (1995).

EFEK BO: Stabilisasi Agregat

…. Diunduh dari sumber: http://www.sciencedirect.com/science/article/pii/S0065211303820060……….. 26/10/2012

A conceptual model of aggregate hierarchy in

soils where organic materials play an

important role in the stabilization of

aggregates. Sumber: Jastrow and

Miller (1997)

EFEK APLIKASI BO

…. Diunduh dari sumber: http://www.sciencedirect.com/science/article/pii/S0065211303820060……….. 26/10/2012

A model depicting the dynamics of soil aggregation and the roles of particulate

organic matter (POM) and microbial

metabolites in the stabilization of soil aggregates. From Baldock (2002).

EFEK APLIKASI BO

…. Diunduh dari sumber: http://www.sciencedirect.com/science/article/pii/S0167880906002854 ……….. 26/10/2012

Relationships between soil

organic matter and soil fertility.

Bagaimana APLIKASI BO

…. Diunduh dari sumber: http://www.organicagriculture.co/soil-fertility-management.php ……….. 26/10/2012

TINDAKAN PENGELOLAAN

UNTUK

MENINGKATKAN KANDUNGAN BOT

Mengapa BOT harus dipelihara ?

SOM Improves Soil Physical Properties

– Increased granulation and aggregate stability

– Makes heavy soils easier to work

– Increases water infiltration rates

– Increases water holding capacity

– Decreases erosion

If your soil looks like this…

You can avoid this!

BOT memperbaiki sifat kimia tanah

– Increases Cation Exchange Capacity so the soil is better able to store and supply plant nutrients

– Increases pH buffering so the soil resists changes in pH

– Reduces Aluminum, Iron, and Manganese toxicity in acidic soil

Mengapa BOT harus dipelihara ?

Mengapa BOT harus dipelihara ?

Soil organic matter enhances soil functions and environmental quality because it:

1. Binds soil particles together into stable aggregates, thus improving porosity, infiltration, and root penetration and reducing runoff and erosion;

2. Enhances soil fertility and plant productivity by improving the ability of the soil to store and supply nutrients, water, and air;

3. Provides habitat and food for soil organisms;4. Sequesters carbon from the atmosphere;5. Reduces mineral crust formation and runoff; and6. Reduces the negative water quality and environmental effects of

pesticides, heavy metals, and other pollutants by actively trapping or transforming them.

…. Diunduh dari sumber: http://ecomerge.blogspot.com/2010/05/what-is-organic-matter-and-why-it-is.html ……….. 26/10/2012

Apakah BOT ?

• All material in soil that contains (reduced) carbon.

• SOM is derived from– Plant residue (both litter and

roots)– Animal remains and excreta– Living soil microbes

(microbial biomass)• Over time microbes

transform fresh organic material into stable soil organic matter

Crop residue

Bacteria

Fungi Actinomycetes

SOM

Tindaklan pengelolaan untuk meningkatkan input bahan organik ke tanah.

Return more crop residues

Add cover crops

Add other sources of organic material

Diversify crop rotations

Efek Penambahan bahgan organik terhadap Kandungan BOT

• A 30-yr experiment in Connecticut showed returning corn residues increased SOM to 4.6%, compared to 3.4% with no residue returned.

• A rye cover crop will add about 2,000 lb of C per acre from above ground production and about 500 lb C per acre from roots. After one year about 500-600 lb of this carbon will likely still be in the soil.

• An 11-yr study in Vermont showed 20 ton/acre/yr of dairy manure (13% dry matter) was able to maintain SOM levels at 5.2% in conventional tilled corn silage production. 30 ton/acre/yr increased SOM to 5.5%. No manure decreased SOM to 4.3%

Untuk mengurangi kehilangan BOT:

Mengurangi Erosi

Mengurangi olah-tanah

How does tillage affect SOM decomposition?• Residues are mixed

with soil– Physically breaks

residue into smaller pieces

– Intimate contact between soil and residue

• Aerates soil• Breaks apart soil

aggregates, exposes protected SOM to decomposition

• Promotes erosion losses

Tillage mixes residues into the soil and in so doing it breaks residues into smaller pieces and puts them

into intimate contact with the soil bacteria and fungi that are responsible for decomposition.

Decomposition is an aerobic process, and oxidative process that requires oxygen. It is just like burning wood in a stove. You can slow down the process by

reducing air flow into the firebox. Open up the dampers and you can burn a lot more a lot faster. Tillage does the same in soil. It mixes air (oxygen) into the soil and greatly speeds up decomposition

because oxygen is usually limiting in the soil. Some soil organic matter is protected from

decomposition because it is hidden inside soil aggregates and thus is difficult for microbes and air to get at it. Tillage breaks apart soil aggregates and

so exposes more organic matter to the agents of decomposition.

Distribusi Bahgan Organik dalam Tanah pada Kondisi Tanah diolah dan Tanpa-olah

Soil Organic Carbon (g/kg)5 10 15 20 25

Dep

th (c

m)

0

5

10

15

20

25

30

35

No-till

ConventionalTillage

In CT systems, crop residues and roots get mixed uniformly through the plow layer so

there is very little change in SOM in the upper 15 to 20 cm.

In NT systems, crop residues and manures are left on the soil surface and only mixed by worms and other soil macroarthropods.

This means that most added organic materials decay near the soil surface and consequently

SOM concentrations are greatest at the surface and decrease with depth. There is

actually very little difference between the two systems deeper in the profile.

Again, most of these increases are in the active SOM pool. This is the pool with

highest rates of decomposition and turnover of material. But since this is the pool that has the greatest influence on soil aggregation and stability and water infiltration and ease of root extension, it is actually desirable to have this large active pool located near the soil surface.