CHAPTER III. 



How field experiments ought to be made. Form, extent, kind, and condition 

 of the land. Precautions to be taken. What is to be observed and recorded. 

 Quantity of land required for a continuous series of field experiments. Ex- 

 periments should be made with a view to a definite object or end. Evils 

 arising from badly conducted experiments. Why the results of analogous 

 field experiments are often so discordant. Importance of ascertaining the 

 limits of natural variation in the productiveness of an experimental field. 

 Necessity of double experiments. Ought the mean of the natural produce of 

 different parts of a field to be taken as the standard with which to compare 

 the produce of experimental manured portions ? 



A COMPLETE and satisfactory answer to the question, How 

 ought experiments in practical agriculture to be made? re- 

 quires the consideration and discussion of a variety of particu- 

 lars. 



1. Of the form, extent, kind, and condition of the land on 

 which they ought to be made. 



2. Of the precautions to be taken in conducting experiments 

 generally, and of those which are specially necessary in each of 

 the different branches of husbandry. 



3. Of the purpose, immediate or remote, for which the 

 experiments are to be made. 



4. Of the kind of observations which ought to be made 

 during the progress or at the close of the experiment, and of 

 the proper way of making and recording them. 



I shall make a few observations on each of these points in 

 their order. 



1. Of the form, extent, kind, and condition of the land on 

 which experiments ought to be made. 



The form of the pieces of land on which field experiments 

 are made ought to be square or oblong. Allotments of such 



