Sumber:. BIOLOGI TANAH & LINGKUNGAN MIKRO Bahan organik, organisme mikro dan makro (mis. fungal hyphae dan invertebrates), detritus dari fungi dan binatang, bacteria, dan eksudat biologis, semuanya membantu menstabilkan struktur tanah. The role of each part of the biomass differs according to its size. Broadly, large aggregates greater than 250 m m diameter (macro- aggregates), are stabilized by their inherent physical structure, wetting and drying cycles, and organic matter. Mikro-agregat (< 250 mm) distabilkan oleh bentuk-bentuk hidup atau mati dari akar, fungi, invertebrata dan mikroba. ASPEK BIOLOGIS DAN KIMIA PRODUKTIVITAS TANAH

Sumber:. FIGURE 22 - Model of aggregate organization with major binding agents indicated (Source: Tisdall and Oades 1982) - Major binding agent Tanah Pori

Sumber:. Model organisasi agregat tanah dengan bahan perekatnya (Tisdall and Oades 1982) – Akar dan Hifa (keduanya bahan organik hidup) Akar Hifa Agregat tanah

Sumber:. Model organisasi agregat tanah dengan bahan perekatnya (Tisdall and Oades 1982) – Plant and fungal debris encrusted with inorganics (bahan organik persisten) Hifa Bakteri Paket- paket partikel liat

Sumber:. Model organisasi agregat tanah dengan bahan perekatnya (Tisdall and Oades 1982) – Residu mikroba dan fungi encrusted with inorganics (bahan organik persisten) Partikel Liat Limbah Mikroba (material humik)

Sumber:. Model organisasi agregat tanah dengan bahan perekatnya (Tisdall and Oades 1982) – Bahan amorf alumino-silikat, oksida-oksida dan polimer organik yg diserap pada permukaan liat dan ikatan elektrostatika, flokulasi (bahan anorganik permanen) Lempengan Liat Cement = Perekat

Sumber:. Populasi organisme tanah dari semua ukuran berhubungan secara fungsional melalui peranannya dalam degradasi bahan organik tanah. BOT ini meluputi bahan tumbuhan hidup dan mati, serta biomasa organisme lainnya hidup dan mati. Gambar berikut menyajikan jaring-jaring makanan (food web ) dalam tanah. This shows that animals such as nematodes and some fungi feed directly on live plants while other fungi and bacteria feed predominantly on litter. ASPEK BIOLOGIS DAN KIMIA PRODUKTIVITAS TANAH

Sumber:. Representation of detrital food web in shortgrass prairie. Fungal-feeding mites are separated into two groups (I and II) to distinguish the slow-growing cryptostigmatids from faster-growing taxa. Flows omitted from the figure for the sake of clarity include transfers from every organism to the substrate pools (death) and transfers from every animal to the substrate pools (defaecation) and to inorganic N (ammonification). Source: Doran (1987)

Sumber:. Earthworms and other large invertebrates create, and inhabit, burrows and pores, and are very mobile. The most notable of these are termites, which are divided into three groups according to the structure of their nests: those that build mounds (a) above ground, (b) on the soil surface, and (c) below ground. Small arthropods, microfauna and fungi live mostly in larger voids and in association with roots. ASPEK BIOLOGIS DAN KIMIA PRODUKTIVITAS TANAH

Sumber:. Foster (1988) reviewed the location of the various types of soil- dwelling organisms and found that fungi, which constitute about 80% of the biomass in many soils, tend to be restricted to the rhizosphere of roots, to larger pores between aggregates and to the surface of aggregates. Bacteria, by contrast, are found on roots in the rhizosphere, in small colonies in the larger micropores, within aggregates and on and within cell debris. For more information on location refer to Foster (1988). Smiles (1988) describes the physics of the micro-environment of small soil organisms. ASPEK BIOLOGIS DAN KIMIA PRODUKTIVITAS TANAH

Sumber:. BAHAN ORGANIK Tumbuhan dan hewan menyediakan bahan organik bagi tanah. Bahan organik tanah dapat dibedakan berdasarkan struktur kimiawinya, misalnya substansi humik kaya lignin yang sukar lapuk. The standing crop of litter in semi-arid grasslands is usually more than 3 t/ha and in temperate dry steppe may exceed 11 t/ha (e.g., Klemmedson 1989). There has been much debate about the relative contents of organic matter in tropical and temperate soils. Within those wet-and-dry climates that have hot summers assisting rapid decomposition, there is no evidence of inherently lower levels of organic matter in the tropics than in comparable temperate regions (Juo and Payne 1993). ASPEK BIOLOGIS DAN KIMIA PRODUKTIVITAS TANAH

Sumber:. EFEK BAHAN ORGANIK TERHADAP KESUBURAN TANAH (Young 1989) Efek-efek PrimerKonsekwensi Efek Fisika Binding of particles, root action leading to improved structural stability, balance between fine, medium and large pores Improved root penetration, erosion resistance and moisture properties; water- holding capacity, permeability, aeration Efek Kimia Nutrient source, balanced supply, not subject to leaching, with slow, partly controllable, release Including better response to fertilizers, non-acidifying source of N, mineralization of P in available forms Complexing and enhanced availability of micronutrients Increased cation exchangeBetter retention of fertilizer nutrients Improved availability of P through blocking of fixation sites Efek Biologis Provision of a favourable environment for N fixation Enhanced faunal activity

Sumber:. Kowal and Kassam (1978) ; Juo and Payne (1993) mengkaji peranan bahan organik di tanah-tanah tropika. Ternyata BOT mempunyai berbagai efek yang saling bertalian dengan kesuburan tanah. In particular it should be noted that both chemical and physical effects are of relatively great importance in the soils of the semi-arid tropics because these generally have low cation exchange capacity (effective CEC values less than 14 meq/100 g clay). ASPEK BIOLOGIS DAN KIMIA PRODUKTIVITAS TANAH

Sumber:. Kepentingan relatif seresah tanaman (crop residue) dan pupuk kandang sebagai inputs bahan organik, beragam di antara sistem-sistem pertanaman dan beragam secara spatial di salam suatu sistem pertanaman. The figure illustrates the flow of litter, manure and by- products (such as dung cake for fuel) in Indian villages practising approximately one-third single cropping and two- thirds double cropping. Sebagian besar biomasa bagian-tanaman di atas tanah dimakan oleh ternak, tetapi sejumlah yg hampir sama biomasa bawah tanah menjadi cadangan BOT. ASPEK BIOLOGIS DAN KIMIA PRODUKTIVITAS TANAH

Sumber:. Energy flow through the agro-ecosystems. Values are means from five villages = 1 SE (× 10 6 KJ/yr/ha cultivated land solar radiation = 6.5 x kJ/yr/ha (Source: Singh and Singh 1992)