348 



Missouri Agricultural Report. 



are large enough to protect the soil from the drying action of 

 winds sweeping over the surface. 



In the light of some recent investigations it would seem 

 that the value of after-cultivation in conserving moisture under 

 average conditions perhaps has been overestimated and that the 

 increase in yield to be expected from further cultivation after 

 that which is sufTicient to control the weeds is not great. Gates 

 and Cox* of the United States Departrnent of Agriculture have 

 summarized the data published by several experiment stations 

 together with that obtained by their own investigations through 

 a large number of co-operative experiments with farmers under 

 a wide range of soil and climatic conditions. 



In these experiments plats were cultivated in the ordinary 

 way and the yield compared with that of other plats receiving 

 no cultivation but on which the weeds were removed by scraping 

 the surface with a hoe. 



In the following table the results from four experiment sta- 

 tions are summarized covering twelve different trials: 



EFFECT OF CULTIVATION ON YIELD OF CORN. 



Similar experiments were conducted in co-operation with 

 farmers all over the country, the average results of which showed 

 that the yield of fodder on the uncultivated plots was 95 per 

 cent of that on those receiving cultivation, while the yield of corn 

 was 99 per cent of that of the cultivated plots. It is evident 

 then that keeping down the weeds is the most important function 

 of cultivation. 



. The frequency of cultivation is another matter concerning 

 which there is often much difference of opinion. Fortunately, 

 considerable experimental evidence has been accumulated in 

 regard to this point. 



*United States Department of Agriculture, Bureau of Plant Industry, Bulletin 257. 



