SPECIAL FARM TOPICS 203 



farming cannot be kept up much less increased without it. Rota- 

 tion adds system to the management of the farm. It is known def- 

 initely what is to be done each year, making possible an estimation 

 of the general returns that may be usually expected from the farm. 



All plants do not draw to an equal extent upon the various 

 manurial ingredients of the soil. Furthermore, plants are unlike 

 so far as concerns their power to assimilate individual ingredients. 

 This is probably due to their sending their roots to different depths 

 and also to an unlike solvent action of the root juices upon the con- - 

 stituents of the soil. By rotating crops, injury by insects is les- 

 sened. Losses caused by fungous and bacterial diseases may also 

 be materially reduced. The soil is maintained in good tilth, which 

 is an item of great importance. Certain minute organisms which 

 are helpful to plants are more likely to increase in soil where crops 

 are rotated than where no regular system exists. Weeds are more 

 readily eliminated or avoided where crops are regularly rotated 

 than under an irregular, slip-shod system of farming. 



The conservation of the organic matter in the soil is one of 

 the important considerations of crop rotation, and the waste that 

 annually goes on through soil cultivation makes necessary some 

 method of restoring the natural conditions, and rotation is one of 

 the methods employed. (N. La. Ex. Sta. B. 71; Ohio Ex. Sta. 

 B. Ill; S. Dak. Ag. Col. B. 79; R. I. Ex. Sta. B. 75; Bu. Pit. Ind. 

 B. 187.) 



System of Rotation. No general system can be recom- 

 mended. Experiments have not yet been able to establish a sys- 

 tem that will work equally well in all localities. In fact the ex- 

 periments have not demonstrated that a system giving good re- 

 sults on one farm will give the same results on another farm in 

 the same locality. Climate, soil and methods of farming are im- 

 portant factors to be considered in adopting a system of rotation. 

 Efven all tests under practically the same conditions have not been 

 successful. 



In no field of scientific investigation or of the practical ap- 

 plication of scientific principles is dogmatism more utterly out of 

 place than in the study or practice of crop rotation. The factors 

 of the problem are so local and individual in their nature, so closely 

 associated with the local characteristics of each farm and its en- 

 vironment and the individual tastes, abilities, and limitations of 

 each farmer, that no definite and specific directions can be given 

 for establishing a rotation for any farm until all the factors of each 

 farm are as carefully studied. 



Diversified Crops. Another important consideration with 

 every farmer who is planning to diversify his crops in order to 

 secure a system of crop rotation is to adopt one that will enable 

 him to receive the largest cash returns for his crop. All crops may 

 be roughly classified under three heads: Exhaustive, intermediate, 

 and restorative. These terms must not be taken too literally. All 

 crops which are harvested and removed from the land take from 

 it more or less plant food and might therefore be said to be "ex- 



