320 TWENTY-FIFTH ANNIVERSARY REPORT. 
again. Stone fruits following seed fruits gave much better results 
than the reverse rotation. In reply to the second inquiry, it was 
unanimously agreed that excellent grain crops could be raised upon 
land from- which nursery stock had just been removed. 
FERTILIZER ELEMENTS IN FRUIT CROPS. 
Later, an investigation™* was made to determine the amounts of 
nitrogen, phosphoric acid, potash, lime and magnesia used in one 
growing season by bearing fruit trees. From one to three varieties 
of apples, peaches, pears, plums, and quinces were selected for this 
test. The writers call attention to the fact that the results given 
by analyses of the plant do not perhaps correctly indicate the 
actual amount of plant-food required, since excess of any element 
might be taken up on account of its plentifulness in the soil, and on 
the other hand, if certain elements were more plentiful in the soil, 
they might -be taken up in larger quantity to the benefit of the 
plant. They are of the opinion, however, that multiplication of 
data of this kind is valuable since an approximate idea is gained of. 
the quantity of plant-food required-- The different kinds of fruits 
are considered separately. 
Tables are presented giving the analyses of fruit, leaves and new 
wood in the case of apples, pears and quinces ; and fruit pulp, stones, 
leaves and new wood in the case of peaches; and fruit pulp, stones, 
stems, leaves and new wood in the case of plums. From these 
analyses an estimate is made of the amount of fertilizer that should 
be applied to the ground in which fruit trees are growing each year 
in order that there will be no depletion of the plant-food in the 
soil. This information is given in the form of tables, one of which 
is appended below. The amount of plant-food used by the trees, 
branches and roots in increasing their size is not included in these 
analyses. It is stated that if the soil were absolutely destitute of 
these forms of plant-food, this would be the minimum amount that 
should be supplied. Since, however, no soils are absolutely lacking: 
in any form of plant-food, account must be taken of the relative 
amounts of these plant nutrients already in the soil. A statement 
is made that “we can ascertain what we want to know about the 
amount of available plant-food the soil can furnish only by rather 
crude experimenting.” 
™* Bul. 265; same in Rpt. 24:255-275 (1905). 
