14 MASS. EXPERIMENT STATION BULLETIN 328 



precaution would be to plow strips through a mulched orchard so as to divide 

 it into relatively small blocks which would give a chance to check a possible 

 fire. 



Summary 



1. Mcintosh and Wealthy apple trees were observed during a fifteen-year 

 period under a comparison of heavy mulch and cultivation with a cover crop. 

 No additional fertilizer was used on the mulched plots; the cultivated plots 

 received nitrate of soda at the rate of 300 pounds per acre during the last six 

 years only. 



2. The moisture content of the surface layer of soil differed little except 

 during dry periods when it was higher under the mulch. 



3. Soil temperature during the growing season differed little except during 

 warm periods when it was a little lower under the mulch. 



4. After the first three years the soil nitrates were much higher under the 

 mulch, rising to a maximum of over 400 p. p.m. They continued high during 

 the fall and early winter. 



5. This excess of soil nitrates did not produce excessive growth of the trees. 



6. Growth and yield of the trees was greater under the mulch system than 

 under cultivation. The application of nitrate of soda to the cultivated plots 

 was followed by increased growth and higher production with Mcintosh, but 

 with Wealthy the increase was small. 



7. Fruit on the mulched trees matured a little later, but no marked differ- 

 ences in color or quality were observed. 



8. Some of the Wealthy trees were on Doucin stock, identified as Mailing 

 V. On an assumed acre basis these trees produced more heavily than those 

 on standard seedling stocks. The apples were a little smaller. 



9. Premature dropping was greater on the mulched trees and increased with 

 the age of the trees. It varied greatly in different seasons. The percentage 

 dropping was not greater in heavy crop years. Wealthy trees on Doucin stocks 

 dropped less than those on standard stocks. 



10. This work suggests that heavy mulching is a satisfactory system of 

 orchard management. The chief objection is cost. Under certain conditions 

 it may be a desirable system. 



References 



1. Beaumont, A. B., and G. C. Crooks. The Influence of a Mulch on Soil 



Nitrates. Soil Sci. 36: 121-123. 1933. 



2. Beaumont, A. B., A. C. Sessions, and O. W. Kelly. Nitrate Accumulation 



under a Mulch. Soil Sci. 24: 177-185. 1927. 



3. Blake, M. A. Amount of Mulch Material Required by Apple Trees. N. 



J. Agr. Expt. Sta. Circ. 286. 1933. 



4. Cullinan, F. P., and C. E. Baker. Orchard Soil Management Studies. 



