- Sand eunreru,

. General lerrure.

. anwess

. Strucluxe (on, soils).

. Wee—season Il'rumln

- Vegeiauvernduammreelrn" ofa speeru rrvpl.

. Drainage.

. slepe

- Elevauon

- Animal lndlcabols (e g. rernurea inesnape and sine
of mere moundsl

. naminumum iloraeiuily, drill-n52, fatality)

- Cakeni llypes o! sox|s based on slope
relanurrslupsl,

. “Hm” Ind ~eolu~ w — remive (utility lnrr
mperarurel, can also mime waler menuon

- Usage, 2.3 pigmenrs, punery, salr amnion [mm
reeds,

. work neeueu tor erop ian ”logy l'nyul
d-siiiumn)

- Surlabrlrry lor speerire (mp (e g yam soil, raro
sorll smls an be rankzd (or up b, rwelve mp typo,
giving a eomplex elaesilieaupn

- Olga-"c conlenl lapan lnnrr culmm

 

Thus, sophlslmaled assessmenls ol sorls are availabk
[mm mosl agricultural sporerres. However, modern
elarsilicauuns are more cumplex in lerms oi
numenelalure and pnysreal earegorres, and use
srauuaru eoluur ennns iMunsell nnd 0mm), slur-dud
mmpnrisons, sundald sieves and so on

8.4
THE STRUCTURE OF SOILS

Soil is a eompler marerral, and il il has Enough
plesuciry lusually rlay), or glue or fibre lion. mamr
ruurees, n ran be pressed or eompasred lnle
mudbntk's. hard prss. arbalvtd |o elay or smnewure. ln
any ohhneiurms, msuflillleuutophnb

Ullwlllplded soils are open, crumbly, or soft unless
eonrreled by enemreal solules be eompaered by
ploughs, homes, or lullic. crumbly soil! hm
nevennelees . definite smutuw no soil pawns are
m nodules or elumpe held together by room, elay
minerals, and (hmlnl bands. If we speed a plmugh or
flag harmws |hm5h llnese lmgfle iskmblin, msy
may powdu up u my do in a party's ballmrll, UK on
uulbazk roads. 1"Bulldusl” is are men used in me
Ausnallan eulbaelr. A soil selenusl mrprl spuk pl
~snull~l Dlyland Sm!) wirlr a lugh uh cunlenl are
pzrfindally suseopobls In [Out ol crumb mum-s, only
p-nly relieved by apphalion ul gypsum.

m maulleolsorl and snbsml llrarmwerelbe uardl is
as min as IM shine on me skin M an cringe, and nus
manrle exlends as livlng mud below me warers ul
earlh as well as on land It is composed ul mese
elemenls.

136

. MINERALS, mlxmly silica, ruruies oi )mn ind
aluminium and Lvmpkx minerals.

. soil. warms, lreslr, saline, Will.
uld flinch/ed minerals and gut-

- GASES, some leum ale almospbere, olhm ermned
by llre I’m-known bl roelss and llre eaerlr's rubeuor

. m1: FORMS, irom rurrgal spores and baeieria u,
wumbars and 51mm! squimlx, lrrnrr mm rools Io
rrunule meme algee.

r oNCFruVmc REMAINS, rm lrumus el me earrb;
decay/est camp-eased, and leesu alganic mabenal.

Soils rarely menu much below 1—2 in, end are more
oleeu a luring syalem H2 em deep. Subaoils, lacking
use lue componen-s, and buried nails or Mp washed
rins are rare sud momma lb valley floors and dell», or
glaml mmmus.

1p esrlrnare lne propomeu a! elay. 91114 mud, and
coarse panda in soil, a sulfierenl um lesl liar iudgns
me willbflily ol soll lor dam building, mud belelr
cnmtmnian, and emp types), flux a sample ol soil
irem . lew Iyplul ailes, and pour a eup ol soil in a all
gar, and almost wlrlu waler, slulre vrgomsly and lei
lire soil incubus senle our over a day or a weelr (clay
on mlum In nrspension fur up lo a ween. m or so
thy ls needed lor dam walls, and less man llul lor
good mud bricks (wlthont lime or eemenl addedl.

or rhese lraeuons, the muse parueler are men,
:lkhuugh uselul In line sorls as a wind>emslon
damn! Suds are ms: mm. sill n os-om mm. elay
pumdes less man mm mm ll g 0! elay has a surlaee
Imohlplo mmlimtslhztoll gulsanal,

Sol] erumb souolure, alded by lime iealuuml axds
me bonurn, wsethrr ul llrese lrsmions and males
20-60% poR rpaee Tire ergs malerrals and gels
hold me srruerure open in rain, and where planl
numenrs can beepme soluble {or ibwrplwn by ruers

 

' exlng pl-l,

 

50H. Fauczsses.
m use» Mullen ul soil mm Irv lumrs Vu