well drained, well tilled soil will be from ,' to 15° warmei than that of 

 .1 poorly drained, poorly tilled one. Phe reason foi this is found in two 

 facta! (1) rhe behavioi oi different substances toward heat h is more 

 ,1,11,, nil to raise one pound ol watei one degree in temperature than one 

 pound "i "n othei substanci in the soil rhe same heal would warm 

 ,i, N sand to, dr) elaj . . drj loam ,• '. drj muck 01 humus ,'. would 

 warm the lame weight ol watei onlj 1 Phis ma) easily be proven 

 fake •' pound ol watei and 1 pound ol tand .»t the same temperature 

 Heat the sand ti e and put 11 in the watei rhe temperature ol i'" - watei 

 will rise 1", the temperatun ol the sand fall to \ :■.."". take two samples 

 ,.1 in,- .mi.- soil, one saturated, thai is, holding all the watei il can, the 

 othei hall taurated. Hie heal that will 1 1 turated loam ;' will raise 



hall saturated loam 1 ,'. and, i>\ the way, s hall saturated soil is in 

 about the best condition foi tillage, foi germination, and foi plant 

 growth. Hence, from •< temperature standpoint, you can see how essen 

 tial it •• that the soil should not be too wet I 1) ' vaporation cools the 

 soil 1 ii.it this is 10 I 1 in prove to you in this simple way, Here arc 

 iwi> thermometei Phe) both tead 67 lln<- is ,1 wel linen sack that 

 jusl fil • the bulb. One would think il should be the same temperature as 

 tin thermometei 1, foi all have been lying here side b) side 1 slip the 

 wet sack on one thermometei and watch the result. Phe wel bulb reads 

 ,..', i g . 8 G lowei than the dry bulb. Phese readings would vary foi 

 different conditio Phe only possible foi this phenomenon is 



the evaporation from the gauze Phe heat from the thermometei is going 

 into the g w ■ ind into the watei and evaporating the water, You may 

 take a certain amount ol watei md heat il from freezing point to boiling 

 point Yqm cannot make the watei any hotter, yel the flame is sending 

 more heat into it .ill the time What is becoming ol that heat it is 

 being used to nun the watei into vapor, 01 steam, as we say. 11 takes 

 ; -, , times is much heal to turn watei into vapoi as it does to heal it 

 from freezing to boiling In evaporation the same thing is true, only, 

 .in.i- there is no fire to tupply the heat, il must come from the wai 

 it.. -it, 111,1 hence the watei is coldei than the surrounding aii rhe vcr) 

 same phenomenon occurs wherevei evaporation takes place. Hence, the 

 ioonei you gel that dry blanket ol soil on the surface and check the 

 evaporation, the soonei will thai soil become warm and suitable foi seed 

 germination and planl growth 



\ third soil factoi in crop production is the propei supply ol air. 

 VVhethei the roots actually breathe this aii as the leaves do has nevei 

 1, ,-,-n decided, bul the fact remains that the) can no more do withoul it 

 than the leaves can Bui absolute exclusion oi fresh aii occurs onl) 

 when the toil il filled with watei Soils in s good state ol cultivation 

 |, .Mint sufficient change - 11 aii foi ill oui crops but the legumes We 

 have been testing this poinl both last yeai and this year, and that is the 

 conclusion we have irrived at Peas, beans, clover, gov p< is, vetchesi 

 ,-t, , would all be benefited by more aii than r< the roots und 1 



ordinary conditions. Phis may explain why peas do so well on sod the 

 ioil is open in texture md allows much intercli 



Perhaps 'i may be interesting to note some ol ' , "' igencies that pro 

 mote aeration First, there is change oi temperature <•! iix- soil. Phe 



