10 BULLETIN 1378, U. S. DEPARTMENT OF AGRICULTURE 
LABORATORY EXAMINATION OF SOILS FROM ROSETTED AND FROM 
NONROSETTED PECAN ORCHARDS 
The relation between the rosette, the character of tree growth,, 
and the productiveness of pecan trees and soil conditions has been 
investigated in a number of orchards, and the results are given 
in this bulletin. 
It was found that there is a close correlation of high nitrogen and 
organic-matter content of soil with productive trees free from rosette) 
and of low nitrogen and organic-matter content with nonhealing 
rosetted trees. In orchards free from rosette there was invariably 
a correlation of high nitrogen and organic-matter content of soil 
with thrifty, productive trees and of low nitrogen and organic-matter 
content with feeble growth and minimum productiveness. The re- 
sults indicate that it is immaterial whether the increased organic 
matter in the soil is brought about by the use of cover crops 0] 
addition of stable manure or is caused by a natural accumulation of 
litter and debris. 
ORCHARD SOILS EXAMINED 
The relation of soil conditions to the rosette of pecan trees was 
investigated in 11 orchards in southern Georgia, northern Florida, 
and Alabama. The soils of these orchards were examined, because 
in each it was possible to find under the same management both 
rosetted and trees of uniform age and variety growing on 
uniform soil types. In each orchard samples of soils were obi 
from a rosetted and from a healthy section of the orchard. Records 
were made as to the subsoil conditions of the two sections and of 
the cultur an practiced. In each case soil samples were taken 
for laboratory determination of their acidity, nitrogen, and organic- 
matter content. Comparisons were thus made between the soils of 
rosetted and healthy orchards. The data for the soils of these 11 
orchards are given in Table 10. 
ORGANIC MATTER 
The organic matter of the soils in 9 of the 11 orchards in which 
these investigations were conducted was greater in the soil from the 
normal sections than in that from the rosetted sections. In orchards 
Nos. 3 and 5 the organic matter was greater in the soil from the 
diseased than from that in the healthy sections. The subsoil was 
probably responsible, at least in part, for the condition of the trees 
in the diseased sections of these orchards. 
Wide variation was found in the organic matter content in the 
soils of these 11 orchards. In reading these tables, comparison 
should only be made between the soil from diseased and from healthy 
sections of individual orchards and not between soils from different 
orchards, as the data are not presented to show the amount of organic 
matter necessary for healthy pecan trees. The humus requirement 
necessarily varies with different soils, and the data resulting from this 
work are insufficient to determine that question. They do, however, 
indicate that the percentage of organic matter in a soil is an important 
factor in causing or preventing pecan rosette. 
