102 BULLETIN 1105, U. S. DEPARTMENT OF AGEICULTURE. 



are thought to be due to unequal distribution of tree roots. Herbace- 

 ous vegetation is believed to have been a relatively unimportant fac- 

 tor, because it was sparse and closely cropped by cattle. 



A survey of all the soil-moisture data shows a fairly consistent 

 superiority of brush-covered over uncovered ground during dry 

 periods. Against this stands the fact that only in a single instance, 

 namely, the 1914 experiment previously described, has a brush cover 

 proved a really eifective aid to reproduction. This discrepancy is 

 in a considerable measure explained by the fact that seedlings can 

 not grow directly under a dense mat of brush, where the greatest 

 benefits in the way of moisture conservation are secured. Seedlings 

 can grow only under a light cover, in the edges of the larger 

 brush masses, or in openings between branches. Even these situ- 

 ations afford considerable protection against water loss; but, as will 

 be shown later, the seedlings may be forced to yield these benefits 

 to older and more aggressive plants. 



Table 24.- 



-Available soil moisture (percentage of dry weight), 

 ment, Fort Valley, 1919-20. 



'brush expert- 





1919. 



1920. 





Jime 0. 



June 30. 



Aug. 2. 



Aug 



.30. 



Sept 



.15. 



May 17. 



June 4. 





CO 



o 



1 



1. 



CO 



o 



1 



1 



CO 



o 



1 



1 



CO 



o 



1 



1 



CO 



o 



1 



a 



1 



1 



IM 



1 



1 





<N 



o 



« 



CD 



<N 



«D 



Cl 



«o 



(N 



CD 



o 





CD 





No brush 



6 2 



10 8 



1 2 



6 



22 8 



15 6 



7 8 



6 



3 2 



2 9 



7 



Q 9 



4 5 



8 3 



Between branches. 



12.3 



10.4 



-1.0 



4.5 



22.4 



18.2 



12.2 



7.6 



17.3 



11.7 



6.1 6.6 



3.9 



4.7 



Under branches... 



15.8 



12.3 



-0.9 



3.4 



21.5 



15.4 



12.9 



7.6 







6.8 7.9 



6.n 



7.0 



Under litter 



17.7 



11.9 



-0.1 



2.0 







13.7 



9.2 







i 







North edge of 



















brush pile 



18.6 



14.8 



6.1 



3.9 







18.4 



14.2 



































1920. 





June 19. 



July 6. 



July 13. 



Aug. 9. 



Sept. 3. 



Ocl 



.6. 





1 



CD 



1 



1 



CO 



-1 



i 



a 



CD 



1 



i 



1 



CO 





i 

 1 



CO 



1 



(N 



1 



CO 



1 



No brush 



1.8 

 2.4 

 1.8 



5.0 

 2.0 

 2.1 



0.0 



-0.6 



1.0 



2.9 

 5.7 

 2.9 



1-0.2 



-0.6 



0.6 



7.(T 

 3.9 

 2.0 



6.4 

 7.9 

 9.0 



4.1 

 3.9 

 3.4 



0.1 

 4.0 

 6.8 



4.3 



0.6 

 0.9 

 1.9 



5.0 



Between branches 



2.3 



Under branches 



4.7 







Wilting coefficient: Per cent. 



1919. Depth, 2 to 3 inches 7.8 



Depth, 6 inches 11. 3 



1920. Depth, 6 inches 13.1 



Depth, 12 inches 15.4 



I Interpolated July 13. 



