80 MASS. EXPERIMENT STATION BULLETIN 339 



yield and more especially on the color and appearance of the fruit. There were 

 six plots of two or three trees each separated by a guard tree. Each tree re- 

 ceived 10 pounds of superphosphate and 3 pounds of sulfate of potash. Nitrate 

 of soda was used on duplicate plots at the rates of 5, 10, and 15 pounds per tree. 

 In 1928 as the larger amounts of nitrate seemed to increase yields with no 

 injurious effects, it was increased to 10, 17J^, and 25 pounds per tree. Be- 

 ginning in 1932 all fertilizer was omitted in the heavier bearing year but applied 

 as usual in the odd years. 



While the trees are so few that the results may have little significance, we 

 believe that they are suggestive. A summary of growth and yield follows: 



Average total 

 Trunk Diameter yields per tree. 



Nitrogen Fertilization 15 years, 



1^2 1 Increase to 1933 bushels 



Light 30.5 15.6 143 



Medium 33.0 20.6 166 



Heavy 34.5 20.5 206 



These figures show increased growth as expected from nitrogen fertilization 

 yet the relative sizes were nearly the same at the beginning as at the end of the 

 test. Apparently yield increases with the increase of nitrogen. Again it should 

 be noted that the yields were in the same order as the size of the trees in 1921. 

 Unfortunately no yield records previous to 1921 are available, yet it was 

 thought at that time that the three groups of trees were nearly alike. One of 

 the heavy nitrogen plots was believed to be inferior to the rest. 



The most important question is whether the heavier nitrogen applications 

 injured the trees or fruit. The color and attractiveness of the fruit was in some 

 years somewhat better with the light application but repeated observations 

 indicate that differences were too small to be of importance. None of the fruit 

 was above average, probably because the soil is too shallow and the subsoil too 

 compact to suit the Baldwin. 



The trees suffered from the recent cold winters but there is little indication 

 of more injury on the high nitrogen plots. It must be remembered that the 

 orchard has a heavy sod, mostly bluegrass. 



The study of these trees suggests that while liberal nitrogen fertilization may 

 have been profitable there are other factors that were influential — probably 

 soil conditions and water supply, also the fact that a complete fertilizer was 

 used. Such heavy applications of nitrogen alone might possibly have given 

 different results. Winter injury has so weakened the trees that for this and 

 other reasons it is expected that the trees will be removed and the test termi- 

 nated. 



Comparison of Cultivation and Heavy Mulching for Apples. (J. K. 



Shaw. ) This project has continued as before. Results are reported in Bulletin 

 328 issued during the year. The practice of mulching with hay or similar 

 materials brought into the orchard is increasing in Massachusetts. In view 

 of the good results obtained and especially its value in preventing soil erosion 

 and favoring a more uniform and adequate water supply, the practice is to be 

 recommended where the cost is not too great. 



The Effects of Fertilizer Limitation on Fruit Plants. (J. K. Shaw.) 

 This has been continued with own-rooted trees planted in 1931, the fertilizer 

 applications being the same. No radical change has been made in the fertilizer 

 used since 1889 except one change from gypsum to a complete fertilizer. On 

 account of limited space these trees can remain for only a very few years more. 



