2 CIRCULAR 9 5, U. S. DEPARTMENT OF AGRICULTURE 



During the progress of soil-survey work, however, it was observed 

 that the better orchards are not uniformly distributed but are con- 

 fined mainly either to certain localities or to well-defined situations. 

 Representative areas of good orchards are around Republic and 

 Marionville in Missouri and Springdale and Rogers in Arkansas. 

 Hillside and other undulating or gently rolling situations throughout 

 the area are universally recognized as supporting better orchards than 

 level uplands. It was also noted that in those districts and those situ- 

 ations where apple growing is most successful the soil differs from 

 that in places where the industry is less successful. This fact sug- 

 gested a possible cause. The soils of the area were examined, with 

 this fact in mind, and an attempt was made to determine whether 

 differences in those soil characteristics which may constitute factors 

 favoring or inhibiting orchard success coincided with the differences 

 in location or situation. 



AREA STUDIED 



The area studied covers about 4,000 square miles, including New- 

 ton, McDonald, Barry, Lawrence, and parts of Jasper, Greene, Chris- 

 tian, and Stone Counties in Missouri, and Benton and parts of Car- 

 roll and Washington Counties in Arkansas. 



CLIMATIC CONDITIONS 



The climate of the area is favorable to the growth of apple trees, 

 the principal climatic drawback to successful apple production being 

 occasional late spring frosts. 



The average frost-free season ranges from 173 days at Mount 

 Vernon, Mo., in the northern part of the area, to 197 days at Benton- 

 ville, Ark., in the southern part. Hence, the apple crop does not ordi- 

 narily suffer from shortness of the growing season. Sometimes, 

 however, injury to the crop results from heavy frosts or freezing 

 weather in the spring, following periods of warm weather, and from 

 periods of dry weather in late summer and early fall. 



During the last 30 years, for which only partial records are obtain- 

 able, freezing in the spring seems to have caused total loss of the 

 apple crop in one year and heavy damage in one year. During other 

 seasons there have been partial losses. Injury from frost is usually 

 less severe in orchards of strong, vigorous trees 1 than in orchards 

 where the trees are in a weak and unhealthy condition. 



The injury from the occasional periods of dry weather is always 

 most severe in those sections where subsoil conditions are less favor- 

 able. That the susceptibility of the trees in sections and localities 

 where apple growing is successful is slight is one of the facts indi- 

 cating, as will be shown later, that soil character is an important, 

 if not the most important, factor involved. 



SOILS OF THE AREA 



Upland soils of this area have been developed mainly from mate- 

 rial accumulated by the disintegration of gray, hard, nearly pure 

 limestone interbedded with thin layers of more resistant chert. The 

 geologic processes of rock decay acting on these rocks produce red- 

 dish clay in which the chert fragments^ which do not readily decay, 



