49 

 TAKING SAMPLES OF SOIL FOR CONTROL WORK. 



As many of the deductions concerning the character and condition 

 of a soil are based upon the chemical and mechanical analysis of a 

 small sample of that soil, it is important that the sample shall be 

 fairly representative of the entire area to be considered; otherwise 

 the results may be incorrect and misleading. The chief requisite is to 

 carefully examine the whole area in order to determine its general 

 character, and then to take such a sample as will best represent it. A 

 single clod picked up at random, a sample taken from a water- wash- 

 ed knoll, or from a strongly alkali spot, or from a site where ani- 

 mals have pastured, or from a bog, would probably fail to represent 

 the soil of the entire area. 



Samples of soil for Control work must be taken with even greater 

 accuracy than for the ''general" analysis to deterimene its constitu- 

 ents, since the object is to find out the effects of Cropping on the soil, 

 such as the amount of elements removed by the crop, approximate 

 amount of elements in the soil for the following crops, influence of 

 irrigation, cultivation, or fertilizers. 



To secure samples of soil from crop to crop that will represent as 

 nearly as possible the very same soil, samples for the soil Control at 

 Cartavio are taken in the following way: 



The Cartavio estate is divided into sections. Each section is divid- 

 ed into cuartels or fields as nearly rectangular as the bounderies will 

 allow. From a selected corner of the cuartel, a given number of pa- 

 ces are stepped off at right angles to the cane rows; from this point, a 

 given number of paces are stepped off parallel to the rows; here the 

 sample is taken. For example, in the accompanying chart of Section 

 6, the sample of soil from cuartel 4 would be taken at A, which is 

 the point, say, 80 paces along the edge of the cuartel at right angles 

 to the rows, and 80 paces within the cuartel. 



The sample is taken at a depth of from twelve to fourteen inches 

 and according to Standard methods (Hilgard's or the Official Meth- 

 od), first removing all foreign material from the surface soil. The 

 earth is put in a bag that will not lint. In this same way, samples 

 are taken from each of the cuartels in the section. 



In the laboratory the samples are air-dried separately. Exactly the 

 same weights of earth are taken from each sample and thoroughly 

 mixed together and bottled for use for Control analysis. 



In order to re-locate the place of sample, a chart similar to that 



