330 



PRINCIPLES OF AGRICULTURAL CHEMISTRY 



If part of the crop be planted before and part after a rain, the 

 experiment may become valueless. Every precaution should be 

 used to secure a full stand of plants, and if a uniform stand is 

 not secured at the first planting, the whole field should be re- 

 planted. The same number of rows should be arranged on each 

 plot, and the same number of hills and plants in each row, as 

 nearly as possible. The plots should be plowed and cultivated 

 alike, and whatever operation is needed on one experimental plot 

 should be carried out uniformly on all the plots. 



(8) The harvesting of the crop and weighing of yields must be 

 accurate. A small mistake is multiplied many times when cal- 

 culated to an acre. 



(9) Provide liberally for check plots, and for plots on which 

 repetition is made, so as to allow for inequalities of the soil. 



At the Rhode Island Station, 1 the plots are 193.6 feet long by 

 30 feet wide, with 3 foot paths between, and roads at the end. 

 Before the final harvest, the crop from a strip of land three feet 

 wide on the sides and six feet wide at the ends, is cut and re- 

 moved, this leaving exactly one-tenth acre to be harvested. This 

 arrangement eliminates the error due to greater growth on the 

 edges of the plot. 



The importance of continuing field tests several years is shown 

 by Thome.- The results from the first year test on wheat is 

 quite different from the ten year average : 



1 Report for 1904. 



' 2 Ohio Circular No. 96. 



