SEVENTEENTH ANNUAL MEETING. 



147 



not hard to believe that such interference would hinder the 

 proper development and prevent the proper work of roots. 

 The muffler of niulcii, which forms a part of this system of 

 orchard management, would of course intensify the deleteri- 

 ous effects of the sod in the above respect. 



4th. The soil temperature is lower in the sod-mulch 

 plat than in the tilled plat. It is possible that the harmful 

 action of grass on trees may be accounted for in part by the 

 influence of the sod on the temperature of the soil. During 

 the summer of 1907, the soil temperatures were taken in the 

 tilled and mulched plats twice a day for forty-one days, at 

 the depths of six and twelve inches, and under as nearly as 

 comparable conditions as circumstances would permit. At 

 both depths the diiTerence was in favor of the tilled plat. At 

 six inches the diflference was slight, being only one-third of 

 a degree, but for the greater depth, twelve inches, the aver- 

 age in favor of the tilled plat was 1^ degrees. It is not an 

 assumption to say that the higher temperature is most favor- 

 able to the growth of the apple tree, for plant physiologists, 

 soil physicists and bacteriologists agree that an increase in 

 soil temperature is favorable to plant growth. As one of 

 them puts it, "The soil is a great factory that has its produc- 

 tion vastly increased as the temperature rises." 



5th. There are probably differences in the biological 

 or "germ life" activities taking place in the soil. This is a 

 matter upon which I am not qualified to speak with certainty. 

 But I know that the men who are studying soils find that 

 there are various kinds of micro-organisms inhabiting the 

 soil which have nuich to do with the proper functioning of 

 the roots that grow therein. The soil is teeming with count- 

 less millions of living organisms which bring about necessary 

 changes of one kind and another in that soil ; without them 

 higher vegetation would not grow. Now the activities of 

 these beneficent organisms are deijendent on soil conditions, 

 and King tells us. in the quotation given above, that tillage 

 induces a strong growth of soil micro-organisms ; that "it 

 improves the tilth so that soil organisms may spread readily 



