CHAPTER XIII 



ORGANIC MATTER FOR CORN LAND 



Organic matter has several important functions in the 

 soil : (1) As a direct source of food supply. Decaying 

 vegetable and animal matter contains all the essential food 

 elements of plants. (2) As a means of freeing unavailable 

 plant food elements in the soil. The organic acids given 

 off by decaying organic matter act directly on the elements 

 of the soil, in bringing them into solution. (3) The phys- 

 ical condition of the soil is affected in a remarkable degree 

 by the presence of even a small percentage of organic 

 matter. Note the effect on a clay soil when a few loads 

 of manure are applied to an acre of land. The organic 

 matter improves the granulation and increases the water- 

 holding capacity to some extent. Aeration is also im- 

 proved. (4) A very important effect is to improve the 

 soil as a medium for the growth of soil bacteria and fungi, 

 which in turn become a source of organic matter to the 

 soil. (5) Nitrogen-fixing bacteria are favored by abundant 

 organic matter, if sufficient lime be present. 



Considering the fact that corn, in common with all 

 cereals, must be grown without the extensive use of com- 

 mercial forms of fertilizer, maintaining the supply of organic 

 tnatter in the soil becomes the most important single consid- 

 eration in extensive corn-growing regions. 



94. Good corn soils are rich in organic matter. Two of 

 the best corn soils in the Central States are Miami black 

 K 129 



