436 ANNUAL. REPORT OF THE Off. Doc. 



THE ADVANTAGES OF A KNOWLEDGE OF CHEMISTRY TO 



THE FARMER. 



BY PROF. FRANKLIN MENGES, York, Pa. 



We need not demonstrate that different soils and crops require 

 special methods of cultivation and fertilization to produce the best 

 results for the farmer and the soil, and that a knowledge of chem- 

 istry is of advantage to the farmer in this work is equally axiomatic. 



The time was when the farmer's efforts were directed to produce 

 ihe largest crop possible, regardless of the consequences to the soil; 

 but now he considers his soil also, and farms to produce the best 

 conditions in the soil for the rotation he follows, so that each crop 

 shall leave the soil physically and chemically better than it found it. 



^^'e may say, in passing, that in this discussion we do not forget 

 that the physical conditions of the soil must not be neglected, nor 

 the preferences that certain jilants manifest for certain types of soil, 

 such as the potato for a sandy soil, corn for a medium sandy and clay 

 soil, wheat for a silt soil, etc., all of which seems to be largely 

 due to the physical conditions of the soil, such a® its water-holding 

 power, the prevention of loss of water by evaporation and the tem- 

 perature required by those plants for growth. 



If these are facts, and we do not question them, then certainly a 

 study of the water-holding capacity of any soil is important; how to 

 increase and under certain conditions diminish it, how to prevent 

 loss of water by evaporation, how to increase capillary action, and 

 how to check it, when to roll and when to cultivate a soil to retard 

 or facilitate these processes, when to practice sub-soiling, when to 

 mulch a soil, when to plow deep and when shallow, when to practice 

 fall and when spring plowing, how to drain to prevent surface accu- 

 mulation and loss of water, how to counteract the detrimental in- 

 fluences on the water-holding power of soils in recently deforested 

 regions where the atmosphere seems to have become dryer and the 

 soil harder, because of the loss of water formerly transfixed by the 

 vast forests and given to the air, but which is now largely derived 

 from the soil. 



IJut a study of the temperature conditions of soils is equally im- 

 portant, for all plants require a certain amount of heat for germin- 

 ation, growth and development, and to know how to change the tex- 

 ture of a soil by its introduction of organic matter to furnish material 

 for combustion and the absorption of solar heat demands the care- 

 ful consideration of the farmer. 



