HEAVY MULCHING IN BEARING APPLE ORCHARDS 



By J. K. Shaw, Research Professor of Pomology, and L. Southwick, 

 Technical Assistant in Pomology 



Apple orchards in Massachusetts are managed under various systems of 

 culture. Some are cultivated, with a cover crop, either seeded or of weeds, 

 allowed to grow through the latter part of the season. Many are in sod, the 

 grass in most cases cut and left in the orchard but occasionally harvested and 

 used for feeding purposes. In a few orchards various kinds of mulching 

 materials grown elsewhere are brought into the orchard and spread under the 

 trees. All sorts of modifications and combinations of these systems may be 

 found. 



The amount of brought-in material in mulched orchards varies greatly. 

 This practice is meeting with increasing favor. If there is enough mulch, 

 grass and weeds are more or less completely suppressed and do not rob the 

 trees of moisture and plant nutrients. There is also less loss by drainage and 

 there may be less runoff of rainfall. The root system of the trees is not dis- 

 turbed as it is under cultivation. This system would seem to supply excellent 

 conditions for vigorous growth of the trees and satisfactory production. Were 

 it not for the difficulty of obtaining sufficient material and the labor and ex- 

 pense involved, mulching might be generally recommended as an excellent 

 system of soil management for orchards. 



Review of Literature 



Stewart of Pennsylvania Station reported in 1915 ( 10 ), the effects of cultural 

 methods on tree growth. The soil was a glaciated, Volusia silt loam and was 

 planted in 1908. Mulching "to prevent any appreciable growth of vegetation 

 immediately over the majority of the tree roots" was compared with tillage 

 and cover crops, tillage and intercrop, and tillage alone as methods of culture. 

 The author concluded that "orchard tillage is simply to be regarded as pref- 

 erable to sod or to the presence of other unfilled intercrops, but that it is not 

 equal to a definite mulch either in moisture conservation or in promoting the 

 growth of young trees." 



However, working with more mature orchards, he found some "reversals of 

 previous forms ' not so much in regard to yield as in regard to growth. The 

 soil was a sandy loam and the trees (Baldwin and Spy) were thirty-six years of 

 age at the start of the experiment in 1907. On the mulched plots, annual appli- 

 cations of swamp hay at the rate of about three tons per acre plus the inter- 

 growth (which was light) were made. Yield and growth of the trees on these 

 mulch plots were compared with yield and growth of the trees grown under 

 the ordinary cultivation - cover crop system. "When no fertilizer was given 

 in these experiments, average growth and annual yields were greater under 

 tillage and cover cropping. But where either manure or commercial fertilizer 

 was added in definite amounts to both systems of culture, the mulched trees 



