PRACTICAL MODE OF TESTING THE SOIL. 109 



number of fertilizers, which is assumed to be ten, be 

 multiplied by three, and that product bj three again, 

 it will show how many points of information would 

 arise from such a combination of experiments. 



To make this clearer, we will suppose that he ap- 

 propriates to each fertilizer several rows through 

 the field, amounting to two square rods of ground ; 

 making, when the fertilizers are all applied, twenty 

 square rods. He next applies, on the adjoining twenty 

 rods, the same fertilizers in larger proportions ; and 

 again, on a similar section, the same fertilizers once 

 more in still larger quantities. He now has sixty rods 

 planted, and thirty different conditions of manure. 

 Thus far, however, the applications have all been 

 made in one way only. The manures have been 

 ploughed into the soil before planting. On the next 

 sixty rods, therefore, he duplicates the amount already 

 planted, making no change, except that the manures 

 are now applied in the drill. Finally, he plants a 

 third section of sixty rods, in the same manner as be- 

 fore, with the exception that the fertilizers are applied 

 differently, by combining the two previous methods 

 into one. He now has his corn growing under ninety 

 different conditions of fertilization, on one hundred 

 and eighty rods, or a fraction over one acre. 



In whatever way these experiments may each one 

 terminate, if they have been rightly performed, his 

 object is gained. The results, it is true, may not all 

 be equally definite and certain ; this is not to be ex- 

 pected. Yet he derives some hint, or information, 

 more or less plain and positive, from each separate 



