THE APPLICATION OF NITROGEN -CARRYING FERTILIZERS 205 



practically doubled; this increased shoot growth was accompanied by a 

 corresponding increase in leaf number. Furthermore there was a great 

 gain in leaf size; this increase coupled with the greater number of leaves 

 multiplied the total leaf area by three or four. In commenting on this 

 effect of nitrogen, Alderman- remarks: "... for every foot of bearing 

 surface on the check tree the fertilized tree carried over 23^-^ feet of wood 

 upon which fruit might be borne. This difference in size has been increas- 

 ing so that the ratio would be much greater in favor of the nitrogen 

 fertilized trees at the present time after 4 years of treatment." Inci- 

 dentally the data presented in this table verify earlier statements to the 

 effect tjiat few orchards require potash, phosphoric acid or lime. 



In Apples. — Lewis and Allen^^^ have reported practically the same 

 influence on the shoot growth and foliage of apple trees in the Hood River 

 valley, Ore., when nitrate of soda was applied to bearing apple trees in a 

 rather weakened condition. They observed an even more striking change 

 in the color of the foliage, which was pale j^ellowish green in the check 

 plots and dark rich green in those that were fertilized. Still another 

 effect noted many times is delayed leaf fall. This delay may vary from 

 a few days to several weeks. Since the leaves late in the season can 

 build elaborated foods for winter storage and spring utilization, this 

 delayed maturity may bring about an accumulation of materials which 

 might promote greater vegetative growth the following season and main- 

 tain the tree in a more vigorous condition. At the same time, however, 

 danger from sharp fall frosts or early freezes is increased, especially if 

 applications are heavy enough to force the formation of new vegetative 

 tissues late in the season. Consequently considerable caution should be 

 exercised to apply nitrogen so as to postpone leaf fall but not materially 

 to delay maturity of wood. 



In Strawberries. — Chandler-^ reports that nitrogen in either nitrate 

 of soda or dried blood applied to strawberry plants in the spring before 

 the crop is harvested causes excessive leaf growth and that when the 

 latter material is applied even a year before the crop is to be harvested 

 it causes considerably increased vegetative growth. This excessive 

 leaf growth was found to be associated with decreased fruit production. 

 I Negative Results. Nitrogen Not a Limiting Factor. — On the other 

 Tiand, Hedrick and Anthony^*^ in reporting the results of 20 years of 

 experimentation with fertilizers in apple orchards in New York state: 

 "... heavy applications of nitrogen in a complete fertilizer and in ma- 

 nure have not increased tree growth. " The results obtained by Stewart^^^ 

 in Pennsylvania from the use of nitrogen-carrying fertilizers in bearing 

 apple orchards are for the most part in accord with those of Lewis and 

 Allen; at least most of his applications of nitrogenous fertilizers resulted 

 in increased vegetative growth. However, some of these increases 

 were comparatively small and there were a few instances in which no 



