THE APPLICATION OF NITROGEN-CARRYING FERTILIZERS 217 



In a later chapter it is shown that, within certain Hmits, the plant 

 shows very much the same response to certain kinds of pruning as it 

 does to apphcations of nitrogen-carrying fertihzers. In other words it is 

 possible within certain Hmits to accomplish by proper fertilization 

 results comparable to those produced by pruning. This is true par- 

 ticularly in the effects of these two practices on new shoot and leaf growth, 

 on the better setting of fruit and on the size of fruit. Probably for 

 best results there should be a judicious combination of both practices. 

 For commercial production, however, it will often be found more practic- 

 able to reduce the pruning to a minimum and to depend rather on 

 fertilization. Fertilizers are comparatively cheap and they are quickly 

 and easily applied. On the other hand pruning that is properly done 

 requires considerable judgment and skill and is comparatively expensive. 

 To the extent that the same results can be obtained by the two methods, 

 much greater profits will be realized from the investment in fertilizers. 



Summary. — In many cases the use of quickly available nitrogenous 

 fertilizers in the orchard has resulted promptly in considerably increased 

 vegetative growth, the response being evident in longer shoots and in 

 greater numbers of leaves that are larger in size and darker in color 

 than those of unfertilized trees. For the most part these responses 

 have been made by trees recently showing a lack of vegetative vigor, 

 trees most likely to be found in sod land or in infertile soils. On the 

 other hand there has been little evidence of increased vegetative growth 

 from the application of such fertilizers to moderately rich soils in which 

 the trees are already making a good growth. In many orchards, therefore 

 nitrogen is not a limiting factor to growth and in those where marked 

 responses are obtained from moderate applications, larger applications 

 often evoke no greater response. Increased blossom bud formation 

 often accompanies the increased vegetative growth that follows the 

 use of nitrogenous fertilizers. Fruit setting in trees showing poor vege- 

 tative vigor is greatly increased. The size of the fruit may be decreased 

 or increased by the use of nitrogenous fertilzer depending on whether water 

 is a limiting factor. The correlation between the amount of new vegeta- 

 tive growth and fruit size is generally positive but not high. Yield, which 

 is a product of fruit bud formation, fruit setting and subsequent develop- 

 ment, naturally is often increased greatly by nitrogen applications. 

 The development of the red color of many fruits is somewhat checked 

 by the use of nitrogenous fertilizers because of the heavier shade incident 

 to the increased vegetative growth. Within fairly wide limits fruit 

 production is found to increase with an increase in vegetative vigor. 

 The general effect of nitrogenous fertilizers is to delay maturity of 

 both wood and fruit. Though some influence is shown on the composi- 

 tion of the fruit, in most cases this is of secondary importance. 



