362 HOW THE NEEDS OF SOILS MAY BE DETERMINED 



In scientific studies, it is necessary to extend the tests over many 

 years before accurate results can be obtained regarding the 

 proper soil treatments and the maintenance of fertility. Such 

 scientific work is much more difficult than ordinary chemical 

 analysis or pot tests. 



How Experiment Stations Conduct Tests. Nearly all of the 

 Agricultural Experiment Stations are conducting field tests, some 

 of which are very extensive. The size of the individual plots is 



usually one-tenth of 

 an acre, each carefully 

 measured and perma- 

 nently staked. Figure 

 227, representing one 

 of the many series of 

 plot tests established 

 by the Ohio Station, 

 illustrates how this 

 work is done. 



This particular 

 group of plots repre- 

 sents block D in 

 Range IX on the east 

 side of the Central 

 Farm at Wooster, 

 Ohio. Block D is one 

 of five in an experi- 

 ment begun in 1893, 



FIG. 228.-A small plot left unlimed as a check. tO determine the effect 



of fertilizers and lime 



on corn, oats, wheat, clover and timothy in a five-year rotation. 

 It is to be observed that each block consists of thirty plots, 

 each sixteen feet wide and sixteen and one-half rods long. The 

 soil treatments are indicated in the diagram. The west half 

 of each block, or of each plot, is limed, while the east half is 

 left unlimed. The results are secured by harvesting the crop 

 on each plot separately. The yields are carefully determined and 

 recorded (Fig. 229). 



How Farmers Can Conduct Field Tests. The farmer is a 

 busy man and therefore has not the time to devote to much 

 experimental work. That is the business of the Agricultural 

 Experiment Stations. But the Experiment Station can not do 



