669 



be deteniiiiied in this or in similar samples taken from the field. Similar 

 Avork can be ddiic on samples of soil and snbsoil bionj;ht from a distance 

 and loaded into tnl)es, bnt the chaiii;es dne to the drying ont of the soil 

 and the (lilhculties of loading the soil into the tnbes are such as to make 

 the method unsatisfactory for conii>aring soils from ditt'erent localities. 

 Eight inch argand lamp chimneys with linen tied over one end may be 

 conveniently used as soil tulies. 



The eil'cct of fertilizers on the texture of soils opens ui) a wide field 

 of investigation. The eftect on the surface tension or contracting 

 power of the soil moisture has already been referred to, but there is 

 also a more permanent effect of the fertilizers on the arrangement of 

 the soil grains through flocculation or the reverse, by which the rate 

 of circulation of water within the soil may be very greatly modified. 

 Experiments could be very conveniently <'arried on in tubes or pots, 

 noting from time to time the effect of the fertilizers on the evapora- 

 tion from the soil or on the time it takes a quantity of water to pass 

 through the saturated material. The per cent of empty space in the 

 soil must be given in all cases. 



A method is here given for the determination of the actual rate of 

 circulation of water in the soil in its natural position in the field, and 

 "it has been suggested that a relative rate of circulation can be cal(;u- 

 lated from the mechanical analysis. The difference between the 

 observed rate and the calculated rate of circulation as compared with the 

 type soil, will sliow the difference in the arrangement of the soil grains 

 and in the amount or infiueiiee of the organic matter. If a soil is thus 

 shown to be either more open or closer in texture than the type soil, 

 -then the class of fertilizers best suited to the improvement of this local 

 soil will be indicated. Actual pot experiments, with or without ])lants, 

 can be made to confirm this and to show that these conditions in the soil 

 can be so changed as to adapt them to the need of a particular (;rop. 



A convenient method is needed for the determination of the moisture 

 in the soil in its natural position in the field, as part of the ordinary 

 metetu'ological observations of an ol)serviug station. The ordinary 

 gravimetric method of determining the moisture in a sam^jle of sod 

 removed from the field is too inconvenient, and the results are not 

 strictly comparable, as different samples of the soil have to be used for 

 each determination. 



Several methods have been proposed for determining the amount of 

 moisture in the soil without removing the sample from the field. A 

 method based on the change of electrical resistance of the soil with 

 (5hangiug moisture content gives promise of good results if good con- 

 tact can be secured between the soil and the plates. The method 

 consists of burying i)lates of carbon or of some other good conducting 

 material in the soil at such distances apart that the eleetrieal resist- 

 ance of the intervening soil Avill be about 1,000 ohms when the soil 



