CHAPTER XXVI 



THE EFFECT OF GRASS ON TREES 

 (Reports, I, 97; II, 160; III, 3 ; V, 46; XIII, i; XIV, 



Appendix) 



THE story of the Woburn investigations on this subject is 

 necessarily a long one, for the work started with the existence 

 of the farm, and has been in progress ever since. The time 

 which has been devoted to it, has, however, been justified by 

 the results, for the question has developed into one of funda- 

 mental importance wherever crops of any sort are grown. 



Roughly, the work may be divided into (i) the examination of 

 the effect of grass on trees, which is but one particular instance 

 of the general phenomenon ; (2) the search for an explanation of 

 this effect ; (3) the extension of the observations to plants in 

 general, and, finally, (4) the study of another particular instance 

 the effect of similar plants on each other when massed together. 



Some of the plots .of standard and bush apple trees planted 

 in the farm in 1894-5 were grassed over in the following season, 

 sowing seeds recommended as suitable for grassing orchards on 

 heavy land. The results are sufficiently illustrated by photo- 

 graphs of some of these trees (Figs. 29 and 30) taken three 

 years later ; a quotation of the values obtained on measuring the 

 vigour of the trees would hardly be more impressive. It need 

 only be added that no form of ill-treatment examined at Woburn, 

 except lifting the trees every year, caused a reduction of vigour 

 comparable with that produced by grass. Bramley's Seedling, 

 which is shown in the illustrations, is a very strong-growing 

 variety ; other varieties of a weaker habit Cox's Orange Pippin, 

 Lane's Prince Albert and Potts' Seedling were examined in the 

 same way, and gave even more striking results. 



It was at first considered probable that such an effect was the 

 result of grassing the trees before they had become well estab- 

 lished in the ground, and that the results would be very different 

 with trees which were in a state of vigorous growth. But the 

 case proved to be otherwise : plots of Bramley, Cox and Potts', 

 which had been growing in tilled ground for four years, were 

 laid down to grass. The effect was remarkable ; all growth was 

 arrested, even in the first year of the grassing, and within five 



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