NOTES ON THE PRESENCE OF NITRATES IN 

 ORCHARD SOILS. 



By J. H. GouRLEY AND V. D. Shunk. 



Much has been written on tlie various cultural systems used 

 in apple orchards and considerable data have been presented to 

 show the effect of each of the systems on the growth and yield 

 of the trees. Some general recommendations are now considered 

 standard and are in common use, e. g., most authorities agree that 

 to grow trees in sod is usually not a good practice but that the 

 grass mulch system is" a perfectly practical method of culture 

 especially when accompanied by the use of fertilizers. There is 

 also general agreement that tillage in the orchard is quite bene- 

 ficial and will stimulate growth and increase production, and when 

 the use of cover crops accompanies it the value is enhanced. 

 Some information is also at hand to show the effects of these sys- 

 tems on the soil but all mooted questions in this regard do not 

 appear to be satisfactorily answered. 



It is the purpose of this paper to present some additional data 

 showing the effect of sod and tillage on the presence of nitrates 

 in the soil, and to partially correlate these with the behavior of the 

 trees as regards yield and growth. Primarily the writers are 

 interested in determining some of the reasons why trees behave 

 differently under different cultural treatments and why fruit 

 buds are formed with abundance when grown under a good system 

 of culture and greatly reduced when grown in sod land without 

 fertilizers or tillage. The observations here reported are made 

 as a corollary of such a study. 



In Technical Bulletin No. 9, N. H. Elxperiment Station, the 

 senior author makes the statement that the formation of nitrates 

 is greatly reduced in a sod orchard. But the evidence presented 

 at that time showed only that less nitrates were recovered in our 

 soil samples during the growing season under sod than where 

 tillage was practiced, and therefore would not show conclusively 

 that nitrification was not active under sod, but rather raise the 

 question whether the grass and trees together did not use up 





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