58 STATE POMOLOGICAL SOCIETY. 



First, it makes the soil fine and loose and favorable for the 

 growth of roots. A crop cannot grow on a stone wall nor on a 

 bank of stiff clay, yet either may contain as much mineral food 

 as a rich garden loam. The soil must be fine, and open, for the 

 highest development of plants. 



Second, it acts as a dressing of fertilizer, as it helps liberate the 

 unavailable plant food. I imagine that every acre of land in 

 Maine is rich in potential plant food which only needs to be awak- 

 ened for the use of the plants growing on it. An acre of soil may 

 contain from 5,000 to 30,000 pounds of potash, and from 2,000 to 

 8,000 pounds of phosphoric acid in the first foot, and I imagine 

 that there is not an acre of Maine soil that will not exceed the 

 minimum figures in its native fertility. Exhausted soils ! Where 

 are they ? Abandoned farms whose fertility has been exhausted ! 

 Their plant food is only locked up and the key thrown in the well 

 "by those who have abused them. They need working. They 

 need vegetable matter and a rational system of agriculture that 

 does not burn them out. 



Tillage then helps Hberate plant food, putting the soil in condi- 

 tion so that the chemical activities and the biological activities 

 within it can progress more rapidly. One of the most emphatic 

 problems in modern agriculture is how to get these stores of plant 

 food out of the soil, rather than how to buy them in the form of 

 commercial fertilizers. 



Third, it acts as a continuous gentle irrigation in that it pre- 

 vents evaporation. Tillage prevents evaporation by making the 

 surface layer coarser than the underlying ones, putting the soil 

 in condition so that the chemical activities and the biological 

 surface layer coarser than the underlying ones. The water rises 

 by capillary attraction until it reaches this coarse layer of soil 

 where it is held, and a rational system of tillage is one that con- 

 tinuously preserves this soil mulch. 



And fourth, it kills weeds. This last function has been the 

 principal reason for a large part of the tillage of the past. 

 Blessed be weeds ! 



Soils are made up of a number of mineral elements formed by 

 the disintegration of rock and of organic materials such as leaves 

 and sticks and stubble and the roots of plants. This organic 

 matter is essential to a fertile soil but its content is constantly 

 reduced by long continued cropping and cultivation unless some 



