FERTILIZERS 



167 



showed an increase in yield of more than 30 per cent at the 

 end of fifty years. 



The stabiHty of the soil was demonstrated in a different 

 way at the EngHsh Rothamsted Experiment Station. Wheat 

 was grown without fertiHzer appHcation for many years on 

 the same soil, with a gradual reduction of yield, but after the 

 field was fallow for two years the yield was restored. It may 

 be assumed that the elements were gradually becoming avail- 

 able during the two years and were sufficient to produce a 

 good crop. The one good crop, however, reduced the soil to 

 its former infertile condition. It has been said that the aver- 

 age soil has enough of the essential elements to supply crops 

 for hundreds of years if they were all available. 



Since a chemical analysis of a soil will show the soluble 

 and varying amounts of the insoluble elements it is clear that 

 the result would not indicate the fertilizer needs. The best 

 quick method is one in which a color reaction is used to indi- 

 cate in a general way the available amount of each element. 

 With this information and the knowledge of the previous 

 treatment of the soil, fertilizers can be applied most effi- 

 ciently. Several such "Soil Testing Sets" are on the market, 

 but considerable practice is necessary before they can be 

 used successfully. It is often better to write your State Ex- 

 periment Station for directions for collecting a soil sample 

 and have them make the tests. Recent methods have been 

 devised to make tests of the growing plant tissues for the 

 elements most likely to be deficient. This method is best 

 where a continuous check on the needs of the plant is made. 



So many different conditions of the soil and environment 

 exist that it is often wise to experiment with various fertilizer 

 applications on small areas of the lawn and on several differ- 

 ent garden plants. Valuable information regarding the 

 amount and the particular kind of fertilizer best suited to a 

 local situation can be determined. If one, three, and five 

 pounds of fertilizer per hundred square feet of lawn are ap- 



