28 



CIRCULAR 862, U. S. DEPARTMENT OF AGRICULTURE 



Table 10. — Plant weights and yields of beans on soil in small outdoor beds 

 treated with DDT approximately U years before planting, Beltsville, Md., 

 19U9 



Plant grown and data 

 recorded 



Soil on which plants 



Plant response to pounds per 

 DDT shown 



acre of 



Least 



signifi- 

 ; cant 



differ- 

 | ence 1 











25 



100 



400 



1,000 



Henderson Bush lima 

 bean: 



/'Chester loam 



I Sassafras sandy loam 

 1 Evesboro loamy sand 



^j Mean 



VMuck 



Grams 



11.5 



11.0 



8.3 



Grams 



9.6 



10.7 



8.1 



Grams 

 4.6 

 7.9 

 4.6 



Grams 

 2.4 

 4.5 

 3.8 



Grams 

 1.9 

 2.8 

 2.4 



1 



}■ 2.2 



J 



Weight per plant 

 40 days after 



10.3 



9.5 



5.7 



3.6 



2.4 



1.3 



planting. 



13.9 



13.1 



13.5 



7.7 



5.1 



2 2 





'Chester loam 



Sassafras sandy loam 

 Evesboro loamy sand 



j Mean 



(Muck 



/Chester loam 



1 Sassafras sandy loam 

 Evesboro loamy sand 



j Mean 



iMuck 



[^Chester loam 



j Sassafras sandy loam 

 Evesboro loamy sand 



^ Mean 



vMuck 





Seed yield per 

 plant. 



6.3 



5.4 

 4.8 



5.6 



7.4 

 6.8 



5.5 



6.7 

 4.9 



2.0 



4.7 

 2.8 



1.8 

 2.4 

 1.1 



1 



1- 2.0 



J 



5.5 



6.6 



5.7 



3.2 



1.8 



1.2 





5.5 



6.4 



5.3 



7.7 



4.8 



2.0 



Stringless Black Val- 

 entine snap bean: 

 Weight per plant 

 without pods. 



16.2 

 17.5 

 15.4 



14.6 

 17.6 

 11.7 



6.4 



9.8 

 7.2 



3.3 



6.1 

 4.9 



2.2 

 3.6 

 3.0 



1 



\ 3.2 



J 



16.4 



14.6 



7.8 



4.8 



2.9 



1.8 





18.6 



21.0 



20.0 



11.4 



7.3 



3.2 



Weight of green 



25.4 

 20.0 

 20.2 



19.2 

 20.8 



11.2 



1.5 

 7.8 

 2.6 





 

 









 



1 



y 5.5 



J 



pods per plant. 



21.9 



17.1 



4.0 











3.2 





19.8 



17.8 



15.8 



1.5 







5.5 



1 At the 5-percent level. 



all the plants. The lima beans were removed from the pods and 

 weighed from each plot, and the snap bean pods, per plot, were 

 weighed as harvested. The snap bean plants from which the pods 

 had been removed were also weighed. 



Soil samples were drawn in 1949 from the respective treatments 

 for determination of DDT. 



Results 



Analyses of these four soils for DDT content were made by 

 Louis Koblitsky, of the Bureau of Entomology and Plant Quaran- 

 tine, in January 1950, more than 4 years after the single appli- 

 cation of DDT. Since DDT was applied on the surface-acre basis 

 and there was approximately 6 inches instead of 6% inches of soil 

 in the greenhouse benches, the DDT content in parts per million 

 was slightly higher than one-half the number of the pounds per 

 acre applied. 5 Table 11 indicates that DDT in these soils is highly 

 stable and that there was no significant disappearance during 4 

 years. Since parts per million (p.p.m.) is calculated on a volume- 

 weight basis, the apparent content of DDT in the light, bulky 

 muck soil is much higher than in the mineral soils. 



3 One pound per acre of the surface 6 2 3 inches of soil weighing 2,000,000 

 pounds is approximately % part per million. 



