294 Journal of Agricultural Research voi. xv.no. s 



conducted with the soils as nearly as possible to an equivalent moisture 

 content or the same relative degree of wetness. Since there was no cen- 

 trifuge available, this equivalent moisture content was determined by 



Pa^SO^ inp.pm-of dry soil 



JOO 1.800 J.0OO SDOO 7.000 lOfiOO 



-- @@)@€^XX)OC)CXX) 

 fr--;.°: @©©©©@©CXX)00 



sand- 60 1<, 

 loam -z % 



foam-Z% ©^l9fefe)©CJfe)UUvJULy 



sand-so % 

 loom -50% 



SQnd--^0'7. 



IOQni-60'% _ _ _ _ 



sand-zo'% 



loam-ao "^^ _ _ _ ^ 



day — 10 i. 



I cam- so % 

 cloy- zo % 



loam -70 f. 

 cloy -Joio 



loam-bOf, 

 day -■^of. 



loam- so 1, 

 clay - JO •/> 



loam-^0% 

 day- 60% 



loam- JO % 



day -70-f, ^^l^Aii>^V^>A^l>W^^ll>"^ 



toom-zo'^, 

 day -60'!', 



loam-io % 

 day— 10 f. 



clay 



• = one plant mammm = oigm dr/moiter 



Fig. 7.— Diagram showing the number of wheat plants up and the dry matter produced in 21 days in soils 

 of different texture containing sodium sulphate added in various concentrations. Soils maintained at 

 an equivalent moisture content. 



placing the soils at various moisture contents in contact with loam 

 at 20 per cent moisture in sealed vessels and observing by the moisture 

 movements the percentage in each case which was in equilibrium with 

 20 per cent in the loam. 



