HORTICULTURAL RESEARCH 409 



can derive very little nourishment. Yet, in spite of this, 

 manure has had no effect on the trees. 



There are twenty-one plots of dwarf apple trees devoted to 

 these experiments ; each contained originally eighteen trees but 

 the number has now been considerably reduced. They may be 

 divided into three groups : one lot receives a normal dressing 

 of manure, either artificial or natural, this normal dressing 

 consisting of twelve tons of stable manure to the acre or a 

 mixed chemical manure, probably equivalent thereto ; the second 

 group receives less than the normal or no manure at all ; 

 the third, more than the normal, up to ten times the ordinary 

 amount of artificials or two and a half times the ordinary amount 

 of dung : some of the plots receive artificials as well as dung. 

 These dressings have been applied every year since 1895. 



Taking the records for the first ten years, during which the 

 plots contained their full complement of eighteen trees each, 

 those receiving extra manure prove to be only 37 per cent, 

 ahead of those receiving the normal amount ; the plots receiving 

 a deficit are also ahead of the latter but to the extent of only 

 07 per cent. These values apply to the combined results of 

 annual measurements of the leaf-size, triennial measurements 

 of the trees and annual records of the value of the crops. Each 

 of these sets of data gave very similar results. The average 

 difference of about 3 per cent, between the groups of plots 

 under the extreme differences of treatment is so small that it 

 may well be attributed to error. The observations have now 

 been continued with part of the trees during another seven 

 years and the average differences of these later records are even 

 less than those quoted above. 



These results have been put to the test in two different 

 ways. One lot of trees embraced in the experiments was 

 removed after ten years but the manurial treatment of plots 

 was continued and farm crops were grown on them — potatoes 

 for two years and onions for one year ; and it was found that 

 on these crops the manures had the ordinary effect which they 

 have in other soils ; for instance, in one of the seasons the value 

 of the potatoes in the plots with excess of manure showed an 

 excess of 70 per cent, and that in the plots with deficit of 

 manure a deficit of 9 per cent., as compared with those receiving 

 moderate dressings. In the second place, the experiments with 

 apple trees were repeated in a very poor sandy soil and here 



