CONSERVATION PRACTICES FOR TOBACCO LANDS 



17 



records given in table 3 show an average annual increase of 125 

 pounds of tobacco per acre with an annual increase in value of $75. 

 As pointed out previously the 1-percent grade ridge rows gave excel- 

 lent erosion control whereas flat rows run up-and-down-hill caused 

 heavy losses of soil. 



Ridge rows on contour gave good tobacco yields and values but cross 

 wash occurred during heavy rains. Erosion damage was severe on the 

 5-percent grade rows during two growing seasons resulting in 

 droughty soil conditions and greatly reduced yields in the second year. 

 During the next 2 years, the original area with 5-percent row grade 

 was changed to contour ridge rows in order to evaluate the immediate 

 residual effects of this soil loss. Yield results for the 4-year period 

 are compared in table 4. 



Table 4. — Comparison of tobacco yields under contour and 5-percent 

 grade ridge culture, showing residual effect of erosion caused by 2 

 seasons of S-percent-grade rows, Belts ville, Md., 1940-4$ 



Plot 



Treatment 



Crop yield per acre 



1940 



1941 



1942 



1943 



A 



Contour — 4 vears 



Pounds 

 1, 169 

 1, 141 



Pounds 

 1, 137 



686 



Pounds 

 1,050 



Pounds 

 1, 204 



B 



5-percent grade — 2 years 



Contour — 2 vears 





B 



853 



1, 090 





Yield increase due to continuous 

 contour 











28 



451 



197 



114 



Tobacco yields on the two areas were nearly equal the first year, 

 indicating that the initial tobacco-yielding capacity of the 5-percent 

 row area was not less than that of the contour area. The very wide 

 difference in yields the second year shows the quick effects of erosion 

 occurring on the 5-percent row area. Yield differences during the last 

 2 years of the study show some recovery of the eroded area, but during 

 the last }^ear there still remains a 10-percent yield reduction caused by 

 erosion damage. These findings serve to illustrate the lasting effects 

 of severe erosion on this tobacco soil, as well as the rapid occurrence of 

 such damage when improper cultural practices are used. 



During the period covered by these studies at Beltsville, tobacco 

 yield and quality (as reflected by price) have varied according to the 

 rainfall pattern that occurred in the growing season. These variations 

 due to crop response to rainfall have been evident under both good and 

 poor erosion-control practices. The favorable tobacco seasons had 

 sparse to medium rainfall during the first 30 to 50 clays after trans- 

 planting, followed by fairly abundant rainfall about 30 days before 

 harvest. Unfavorable seasons had protracted rainy weather during 

 the first part of the season, or rainfall was sparse during the last part 

 of the season. The three types of rainfall patterns, in relation to 



