440 ■■■ ANNUAL KKPORT UF THE • Off. Doc 



FEEDINO I'OWERS AND HABITS OF SOME AGRICULTURAT. 



PLANTS. 



HY riUIF. I'KANKLIN MENGKS. Ydvk. Pa. 



We kuow that, there is such a thing as the struggle for r^xistence 

 among plants as well as animals, and that in that struggle plants, 

 like animals, have acquired certain powers by means of which they 

 have been able to conquer in the race of life until the stages of ad- 

 vancement in which we have them, these acquired powers having 

 become habits, which we can use in agriculture to obtain the best 

 results for labor and money expended. 



In furnishing plant food to plants we should think of these ac- 

 quired capacities and should apply only such foods for the procuring 

 of which the plant has only slight powers; for if we give the plant 

 what it can get by its own exertion in so far we do it an injury. 



We know that if the growth of trees and vines is strong and 

 rapid in the more fertile soils, that everything is going to wood at 

 the expense of fruit, and that if we desire the best fruit we must 

 check the growth by making the plant exert itself to obtain the 

 mineral foods it needs. 



The sugar beet will not produce the high percentage of sugar in 

 soils in which it can get nitrogen without much exertion. The same 

 is true of wheat, potatoes and other crops. We used to think that 

 the amount of plant food plants removed from the soil was a sure 

 test and indication of their nianurial requirements; and to discover 

 this we analyzed the ashes of plants to find the proportions of the 

 various mineral elements they used, and then applied just what 

 we thought they needed, and awaited the hundred-fold yield without 

 misgivings. We soon discovered that these analysis revealed what 

 the ashes of the plant containcnl, but did not tell us that most plants 

 do not need silicon and sodium; neither did they tell us during what 

 stages of growth they used and needed the largest amount of phos- 

 phoric acid, potash, nitrogen, lime, magnesium, iron, chlorin, etc., 

 nor what particular functions these elements performed in the 

 plant. They did not show, as Loew expresses it: "That every plant 

 absolutely requires a certain minimum of each mineral nutrient^ and 

 if a plant fails to obtain this minimum it can not produce a nor- 

 mal crop and may even prematurely die." 



