62 Third Annual Report 



IV. Tillage is an eminently desirable proposition in the 

 orchard. Not only as a weed killer, but as a means of freeing 

 plant food, of conserving moisture, of promoting the aeration of 

 the soil, and the growth therein of the beneficent forms of micro- 

 organisms. 



Before we take up the consideration of V and VI, which 

 have to do with the purchase of commercial fertilizers, let us 

 consider a few of the broad propositions. 



Roberts some years ago showed that an orchard of thirty- 

 five apple trees, yielding an average of fifteen bushels per tree 

 for twenty years, removed from the soil twice the nitrogen, three 

 times the potash and one and a half times the phosphoric acid 

 that twenty full crops of wheat would remove. More recent in- 

 vestigations by other parties serve but to confirm this general 

 statement. It would seem therefore, that if wheat needs fertiliz- 

 ing, apples need it yet more. The tree roots spread farther it is 

 true than those of the wheat, yet may not on that account neces- 

 sarily gain more plant food. Moreover orchard crops dififer 

 from other crops in respect to fertilization. Several years of 

 preparatory growth of the trees without fruitage is followed by a 

 coincident growth and fruitage. It is a continuous crop which 

 cannot profit by the well known benefits incident to the rotation 

 of crops. 



A study of the functions and eflfects of various forms of 

 deficient plant foods shows that, speaking broadly, nitrogen pro- 

 motes foliaceous growth and retards maturity ; that phosphoric 

 acid, and to some extent lime, hastens maturity ; and that there 

 is a close relationship between both wood growth and sweetness 

 of the fruit on the one hand and the use of potash on the other. 

 Potash, particularly if not in forms other than muriate, tends to 

 promote starch formation, and starch is the mother substance 

 from which is formed both wood and sugar. 



Now taking up propositions V and VI, the buying of com- 

 mercial plant food. 



V. If I were a Vermont orchardist and felt that I must buy 

 the ready-made commercial fertilizer. I should scan the analyses 

 in the bulletin cited at the outset of this article and search for a 

 brand which carried medium amounts, say 2 percent, of a rela- 

 tively slow form of nitrogen, and carrying relatively small pro- 

 portions of nitrate nitrogen; for a brand which carried con- 

 siderable amounts of a rather insoluble form of phosphoric acid 

 which would be apt (though not surely) to indicate the use of 

 bone ; and for one carrying considerable amounts of potash. I 

 wish such an one joy in his task. I have myself scanned the 

 analyses of the entire lot of this year's brands and find not a 

 single one which fills this bill, although one or two of them are 



