APPENDIX. 185 



even 800 Ibs. of salt may be applied per acre before the seed, 

 without injury (in rnoist climate or wet season), not more than 

 200 Ibs. per acre should be put directly on the growing crop. 



Any one may easily select for himself from the foregoing 

 some one or more points that it is desirable to test in his own 

 locality, and will also readily gather the most important cir 

 cumstances that need to be regarded in carrying out an exper 

 iment to a good result. 



We add, however, the following suggestions as to the man 

 ner of making the experiment : 



I. Every experiment should furnish means of comparison 

 with some standard. If, for example, it is sought to ascertain 

 whether salt increases a crop on a given soil, not only should a 

 portion of the crop and soil have salt applied to it, but another 

 portion should be left without the application. If the question 

 is, Is the straw strengthened, or the grain made heavier ? then, 

 obviously, opportunity must be given to observe how strong 

 the straw is, or how heavy the grain is where no salt has been 

 used. 



II. The plots of ground should not usually consist in a strip 

 a few feet wide, or in a few rows of the crop, but in a nearly 

 square surface, so as to have as little edge to the piece as possi 

 ble, for the roots of plants often extend several feet beyond 

 ordinary dividing lines, if the soil be grateful to them. 



III. The experimental ground should be as uniform as possi 

 ble in quality of soil, in tillage, dunging, and exposure, and 

 should all have had the same treatment as regards cropping 

 and manuring for several years previous to the trial. 



IV. The plots should be of good size, at least one-eighth, 

 preferably one-fourth of an acre. 



V. " Everything should be done by weight and measure ;" 

 guesswork is worse than useless. Let the plots be accurately 

 measured, not " paced off." Let the materials added, and the 

 crop removed, be carefully weighed, and not " estimated by 

 the eye." 



