PENGELOLAAN BAHAN ORGANIK TANAH Bahan Kajian MK. Dasar Ilmu Tanah smno.jurtnh.fpub.nop2013

BO yang diaplikasikan ke tanah …. Diunduh dari sumber: 26/10/2012

EFEK BO PADA AGREGASI TANAH …. Diunduh dari sumber: 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 M n+ (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: 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: 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: ……….. 26/10/2012 Relationships between soil organic matter and soil fertility.

Bagaimana APLIKASI BO …. Diunduh dari sumber: ……….. 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 ?

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; and 6.Reduces the negative water quality and environmental effects of pesticides, heavy metals, and other pollutants by actively trapping or transforming them. …. Diunduh dari sumber: ……….. 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 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 No-till Conventional Tillage 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.