123. 



a re*i^ent in freeing p -ic n.cid rind making it -vr liable, "but it 



readily becomes n nuisance. L'.uch jna^rKJcia is injurious to the soil. It 

 is mischievous to plnnt ,-r-.. . , es.iecial.ly if th ao.'. 1 "be deficient in 

 . It may interfere with imbibition (?). 



Insoluble residues (lliCAt) vary in Inr&e lii.-.i^s; thny are 

 greater in huriid than in arid .ri.-'a. 



id cnst v J-3rt B^'/. of indi a soluble ra.-iteriala. 



L ibl . - - wcvirxls. 



jrn i) it in rivery soil. 

 1'uch of the- a from el rs. 



Potaal >da :o r , solution, act us rengonfcu in tlae 



soil, 12 of decor :,poeition rmd recom- 



pcsiticf.s. In ari ; to ft .j.Jlphlates and eoda 



phosphate, oil, I -^ying the floceulcnca of .-oil, 



me >ct - ., ;:.iGC}iiev/ous both pliysically 



>)i"n . of the torup crate zone, especially 



i noils in 1/Kii'i are good; they raay have a low % 



of * .. , ; adi/ig opposes 



alic^li f :. ; oil :b . cam 



1} It decreases ^vriporation ana prevent 3 the alkali from gath- 



er i j r til e 3 u , 1 in e xc e ^ s i ve run o tin 1 3 . 



.'COL of . t . >n of ti-.v... is increawea and bring 



level I-* : :;iv LL the deposition of alkali at 

 - , . 



. una 13. ta in the ?:o:l on ^ra^ing areas. 



cerra IIUKUS . o to the entire mass of decayed vegetation 



on the to _r:ce plant r.if.tcri^lo in the huiaus r : .re coniplex producte 



of ; / ns the kind, ^roporiion r >/id ni io Io,.v.r orga- 



this decay ana the conditions under ivhich they work. The 

 '. ity of luu-ius i- del rmined :.,. tho nature of tl^e original plant mater- 

 condition of dec-'.y. The identity of plant life io lost in 

 Is significant of t; I .-ortance of humus. 



3 cipy be coiix-idered ay a "3tre-^ of material" compared with 

 litutijt: oi' the jull. 



7i nitrogen of the soil is held almost entirely in the humus. Th 



;,lilj of e in a ^raaa lands r .:0il ia J-^/ 



>0-, . is t>/.'t;anic C. 



.146?) -ir4> tl JSJ. Very low; o.ry ^.o.,l surface. 



(0.066?) 0.166,:, :f rt "' W. Subsoil. 



in an old niondow you nay often find 0.;^ . low 



only iBodc-r-te grov/tli texture influences decay. 1'he, presence of 

 mfavo to th cay of )un.. . ie low nitrogen supply 



due to t .nil proportion of clover cov-sr. 



Conciitiora of huriut;; the el-j^ents in IX^HUL; n.'-y be uivided in two 

 grc able in d insoluble in Ikali ^&ii.fr. solutions, 'i^he aoluble 



lly richer ir. l and is often more inilaontial on the soil 



inriolublt.' ^ro .. - -oiuc MOU-JIT. wrl confine the use 



of the terra "humuo" to this .ciore soluble division of hun.ua matt --..v. .Less 

 thnn . I huniurs is . - -s fort., ing -4.29;;; in 



