Drainage in New York. 255 



killing of most of these minute organisms by the soil conditions. One 

 of the first principles in improving such humus soils is to bring about 

 such conditions as will insure their presence and promote their growth. 



The first and most common action of organisms is the decomposition of 

 organic matter by which carbon dioxide is produced. This carbon dioxide 

 in turn greatly assists in the solution of the mineral. They also promote 

 the same process in other ways. Further and even more important, if pos- 

 sible, is their relation to the supply of available nitrogen, that is, nitrates. 

 This compound, which is recjuirecl by all ordinary farm crops, is formed 

 through the action of several forms of bacteria all of which require air and 

 considerable heat. Some of them live on plant roots such as the nodule 

 bacteria of clovers. Others live independently in the soil. The exclusion 

 of air by excess of water not only kills most of these desirable forms, but 

 it promotes the growth of certain other undesirable organisms which 

 destroy available nitrogen and organic matter, often with the production 

 of acid products directly deleterious to higher plants. So that there is a 

 double reason why drainage should, at all times, be as thorough as pos- 

 sible — namely the food supply and such a condition of the organic matter 

 as promotes the best physical condition of the soil. 



(y) Drainage enables the plant to make a better use of the food and 

 moisture supply in the soil. The roots of most farm crops will not de- 

 velop into a saturated soil. If the water table is at or near the surface, 

 the roots spread out laterally instead of penetrating deeply. The direct 

 result is that when the water table is materially lowered later in the season, 

 the roots are left high and dry and quickly reflect drouthy periods of 

 weather. On the other hand, if the soil is well drained, they develop 

 much more deeply and thereby are connected with a larger moisture 

 reservoir and can withstand without injury a much longer period without 

 rain or irrigation. Their flevelopment assists in the improvement of the 

 physical condition of the soil. Equally great is the advantage to the plant 

 with a deep root system of the larger feeding ground. While there is 

 some movement of the food in the soil moisture to the roots, it is equally 

 important that the roots extend themselves into fresh areas of soil. Indeed 

 it has sometimes been suggested that this extension of the roots is more 

 important than the movement of the food to the plant with the moisture. 

 Both the food and moisture considerations are certainly important in the 

 production of maximum crops. 



(8) Drainage greatly rcdtices the injury to winter crops resulting from 

 "heaving" or the freezing of large amounts of water in the soil. This 

 process raises the upper layers of soil, carrying all shallow rooted plants 

 with it, and if some of their roots happen to be fastened in the subsoil, 



