CONSERVATION PRACTICES FOR TOBACCO LANDS 29 



ing row grades and the relationship between the row grades and ter- 

 race grades. These studies showed that under many conditions this 

 row system served as an effective conservation practice, as each row 

 carried its own water on a moderate grade. When properly laid out 

 the row grades will slightly exceed the terrace grades. Under the 

 conditions found on the experiment station fields, the average row 

 grade was approximately 6 inches more per 100 feet than the terrace 

 grade. This increase is determined by variation in slope and terrace 

 spacing. 



For several years this new system has been laid out on fields of 

 farmers in cooperating soil conservation districts. It has proved 

 effective in both the flue-cured and Maryland tobacco belts and is used 

 extensively in some of the flue-cured areas. Results of its use have 

 been watched closely with reference to its effects on soil loss, row 

 drainage, and the growth of the tobacco. Farmer reaction has also 

 been carefully considered and has been favorable. In addition to 

 reduced soil loss and improved drainage, farmers generally report a 

 more uniform growth of tobacco. 



TERRACES OX TOBACCO FIELDS 



In this bulletin terraces are considered chiefly on the basis of their 

 relation to the improved row system on tobacco land. Specifications 

 on terrace design, construction, maintenance, and use on agricultural 

 land may be found in other publications (11. 19) . 



The studies on tobacco land indicate that a basic water-disposal 

 system of terraces and waterways is essential before the improved row 

 system can be generally applied. The use of terraces, in relation to 

 the improved row system, may be summarized as follows : 



1. The improved row system can. if necessary, be used on land 

 which is already terraced. However, the row system is greatly 

 affected by the terrace lay-out and the best results may be expected 

 when the terraces are planned and constructed to facilitate use of the 

 row system. 



2. Terrace grades should be held to a practical minimum on fields 

 with appreciable slope variations, because of their effect on row grade. 

 For the same reason they may be increased somewhat on fields with 

 uniform slope where terraces tend to run parallel. 



3. Grades from 3 to 6 inches per 100 feet are satisfactory for most 

 conditions. Terrace spacing should also be held to a practical mini- 

 mum because wide spacing increases row grade and the volume of 

 water to be handled. 



4. The top terrace should be located as high up the slope as the avail- 

 able outlet will permit. This will reduce the land area above the top 

 terrace which is usually a special problem in laying out rows since 

 there is no upper guide. 



5. In planning the terrace system on tobacco fields the length of 

 terrace flowing in one direction should be held to a minimum by 

 cresting terraces on the ridges and using all well-defined draws as out- 

 lets. This tends to shorten the rows and to straighten out the curves in 

 both terraces and rows. 



