Users viewing topic: & 1 Guest
VanillaGorilla | The Gorilla Guide to PEDS | 13-08-2012 @ 19:49 | |
the UK's leading expert in bio mechanics Member 1973, 7379 posts | Post Edited: 13.08.2012 @ 19:52 PM by VanillaGorilla Thought I'd share what I know on the matter.A ped is a soil particle. There are five major classes of structure seen in soils: platy, prismatic, columnar, granular, and blocky. There are also structureless conditions. Some soils have simple structure, each unit being an entity without component smaller units. Others have compound structure, in which large units are composed of smaller units separated by persistent planes of weakness.Hide Types Platy In platy structure, the units are flat and platelike. They are generally oriented horizontally. A special form, lenticular platy structure, is recognized for plates that are thickest in the middle and thin toward the edges. Platy structure is usually found in subsurface soils that have been subject to leaching or compaction by animals or machinery. The plates can be separated with a little effort by prying the horizontal layers with a pen knife. Platy structure tends to impede the downward movement of water and plant roots through the soil. They are found most frequently in the C, E, Bs and K horizons as well as insesquioxides (very old soils that are rich in iron and magnesium). Prismatic In the prismatic structure, the individual units are bounded by flat to rounded vertical faces. Units are distinctly longer vertically, and the faces are typically casts or molds of adjoining units. Vertices are angular or subrounded; the tops of the prisms are somewhat indistinct and normally flat. Prismatic structures are characteristic of the B horizons or subsoils. The vertical cracks result from freezing and thawing and wetting and drying as well as the downward movement of water and roots. Columnar In the columnar structure, the units are similar to prisms and are bounded by flat or slightly rounded vertical faces. The tops of columns, in contrast to those of prisms, are very distinct and normally rounded. Columnar structure is common in the subsoil of sodium affected soils and soils rich in swelling clays such as the semectitesand the kandite Halloysite. Columnar structure is very dense and it is very difficult for plant roots to penetrate these layers. Techniques such as deep plowing have help to restore some degree of fertility to these soils. Blocky In blocky structure, the structural units are blocklike or polyhedral. They are bounded by flat or slightly rounded surfaces that are casts of the faces of surrounding peds. Typically, blocky structural units are nearly equidimensional but grade to prisms and to plates. The structure is described as angular blocky if the faces intersect at relatively sharp angles; as subangular blocky if the faces are a mixture of rounded and plane faces and the corners are mostly rounded. Blocky structures are common in subsoil but also occur in surface soils that have a high clay content. The strongest blocky structure is formed as a result of swelling and shrinking of the clay minerals which produce cracks. Sometimes the surface of dried-up sloughs and ponds shows characteristic cracking and peeling due to clays. Granular In the granular structure, the structural units are approximately spherical orpolyhedral and are bounded by curved or very irregular faces that are not casts of adjoining peds. In other words, they look like cookie crumbs. Granular structure is common in the surface soils of rich grasslands and highly amended garden soils with high organic matter content. Soil mineral particles are both separated and bridged by organic matter breakdown products, and soil biota exudates, making the soil easy to work. Cultivation, earthworms, frost action and rodents mix the soil and decreases the size of the peds. This structure allows for good porosity and easy movement of air and water. This combination of ease in tillage, good moisture and air handling capabilities, and good structure for planting and germination , are definitive of the phrase good tilth. | ||
deleted2_20210523 | ... | 13-08-2012 @ 19:51 | |
Member 2606, 11453 posts SQ 170, BP 117.5, DL 215502.5 kgs @ 91.6kgs UnEq | deleted | ||
serious_pete | ... | 13-08-2012 @ 19:51 | |
Member 2437, 305 posts SQ 180, BP 90, DL 220490.0 kgs @ 92kgs UnEq | In January 2004, the journal Protein Engineering was relaunched as Protein Engineering, Design and Selection, or PEDS. PEDS publishes research papers and review articles relevant to the engineering, design and selection of proteins for use in biotechnology and therapy, and for understanding fundamental properties of activity, stability, folding, misfolding and disease. The journal has new editors, a new editorial structure, and a new reviewing system to make it a community journal run by protein scientists for their own discipline. | ||
Wiegieboard | ... | 13-08-2012 @ 20:00 | |
as crimson as my last victims underclothing..... Member 899, 11330 posts SQ 180, BP 132.5, DL 190502.5 kgs @ 118kgs UnEq | fantastic | ||
british_beef | ... | 13-08-2012 @ 20:42 | |
Member 1031, 1149 posts SQ 140, BP 120, DL 240500.0 kgs @ 95kgs UnEq | wheres the Vespa ? | ||
MattD90 | ... | 13-08-2012 @ 23:12 | |
Skaven for the win !! Member 2490, 3589 posts SQ 180, BP 120, DL 230530.0 kgs @ 82kgs UnEq | The consequences of talking about peds will be enormous for you I wish I could tell you that VanillaGorilla fought the good fight, and the Moderators let him be. I wish I could tell you that - but sugden is no fairy-tale world. He never said who did it, but we all knew. Things went on like that for awhile - sugden life consists of routine, and then more routine. Every so often, VanillaGorilla would show up with fresh bruises. The Moderators kept at him - sometimes he was able to fight 'em off, sometimes not. And that's how it went for VanillaGorilla- that was his routine. I do believe those first two years were the worst for him, and I also believe that if things had gone on that way, this place would have got the best of him. | ||
slimsim | ... | 13-08-2012 @ 23:22 | |
My asshole is not watertight. Member 2926, 6050 posts SQ 217.5, BP 107.5, DL 225550.0 kgs @ 86kgs UnEq | Post Edited: 13.08.2012 @ 23:23 PM by slimsim ^^^ f**king lol!Even though I wasn't reading it aloud, upon reading "fought the good fight" my Chorley twang suddenly bore the richer, smoother, deeper tones of Morgan Freeman!!! hahaaaa, best post ever! lol EDIT: PS. I reserve the option to change the best post ever status upon a whim! | ||
force10 | ... | 13-08-2012 @ 23:26 | |
Drugs cheat Member 3860, 630 posts SQ 335, BP 210, DL 330875.0 kgs @ 108kgs UnEq | can someone explain to me im thick and dont get it | ||
deleted2_20210523 | ... | 14-08-2012 @ 08:05 | |
Member 2606, 11453 posts SQ 170, BP 117.5, DL 215502.5 kgs @ 91.6kgs UnEq | deleted | ||
chaos | ... | 14-08-2012 @ 08:44 | |
An amazing human being Member 2047, 17156 posts SQ 262.5, BP 170, DL 300732.5 kgs @ 108kgs UnEq | kirkynick said: Funny as Matt! I think VG might win against the powers that be though, what with the size of him. That said, he falls down rather easily doing strongman stuff, so the jury is out on that one. Dunno, he's been really working hard on beefing up....... http://www.gynecomastiasolution.com/wp-content/uploads/2012/04... I may, just may have blatantly ripped off someone else's joke but as it was in my journal it is now my property and as such I can take all credit for this! | ||