4 PRINCIPLES OF AGRICULTURAL CHEMISTRY 



We will begin the study of agricultural chemistry with a study 

 of the chemical laws governing the production of plants. We 

 must study the conditions best suited to the growth of plants ; 

 ascertain how these conditions are filled by the air and soil in 

 which they grow ; learn how to overcome unfavorable conditions 

 in the soil, and how to maintain and increase its productiveness. 

 In addition, we must study the composition of the plant. 



Agriculture Primarily the Production of Organic Matter. 



Agriculture deals primarily with the production of organic mat- 

 ter. Organic matter, for the purpose of the agriculturalist, may 

 be defined as the compounds of carbon which possess chemical 

 energy. In agriculture, inorganic compounds of carbon and other 

 bodies are caused to combine with the energy of the sun, so as to 

 produce organic compounds containing energy, which may supply 

 heat or energy for the use of man or other animals, which may 

 serve as fuel, or be used for other purposes. The primary object 

 of agriculture is thus to store up the energy of the sun. The 

 production of organic matter is accomplished by means of plants. 



Products of Plant Life. The various soil and atmospheric 

 agencies, acting upon the life within the seed, produce a plant 

 built up by sunshine, water, carbon dioxide from the air, and sev- 

 eral mineral substances from the earth. The plant is composed 

 mostly of complex organic substances, rich in carbon, and con- 

 tains a comparatively small amount of material withdrawn from 

 the soil. It is suitable for the food of animals, while the ma- 

 terials from which it is built are not. If dried and heated 

 sufficiently, the plant burns and gives off heat. 



It has been found that the heat which is secured in the burning 

 of plants, or which can be utilized as heat or other forms of 

 energy by animals which consume them, comes from the sun. The 

 energy of the sun is used to decompose carbon dioxide, water, 

 and nitrates, and to form complex organic compounds. These 

 bodies then contain stores of energy which can be utilized by 

 animals or in other ways. Plants thus store up the energy of the 

 sun, and may also be regarded as media for furnishing animals 



