24 Diseases of Truck Crops 



far as the crops are concerned. Most trucking 

 lands contain the nitrifying and denitrifying organ- 

 isms in about equal proportions. To encourage 

 the activity of the one over the other is the aim 

 of intelligent trucking. The denitrifying bacteria 

 thrive best in an abundance of carbohydrate foods. 

 Fresh coarse manure with a high percentage of straw, 

 when applied to the soil, will favor denitrification. 

 It should therefore be avoided as far as is possible. 

 There are, however, market gardeners who often use 

 as much as fifty tons of such manure per acre in ad- 

 dition to a nitrate fertilizer. Such action is very likely 

 to encourage denitrification because of the large 

 amount of carbohydrates incorporated in the soil. 



Indirectly denitrification will finally cause various 

 physiological plant troubles, most of which are little 

 understood. Poor growth and the shedding of 

 blossoms will characterize plants deprived of avail- 

 able nitrogen food. Denitrification may largely be 

 prevented. A judicious use of manure, especially on 

 the heavy soils, drainage, and proper tillage are all 

 factors which induce nitrification, thereby also pre- 

 venting denitrification. 



2. NlTRE-SlCK SOILS 



This form of sickness, peculiar to certain Colorado 

 soils, was carefully studied by Headen x and Sackett. 2 

 Nitre-sick soils are those which contain such large 

 quantities of nitrates that they inhibit plant growth. 



1 Headen, W. P., Colorado Agr. Expt. Sta. Bui. 155. 



2 Sackett, W. G., Colorado Agr. Expt. Sta. Bui. 196:3-39, 1914. 



