32 MANURES FOR FRUIT TREES 



transformation in the stored up food, and in various 

 ways prepare the soil for ensuring the best results 

 in due course. 



The land should also be properly drained, as a 

 water-logged soil is detrimental to the proper 

 growth of fruit and other trees, causing a reduced 

 vitality or unhealthy condition — a condition in 

 which the trees are prone to the attacks of parasitic 

 fungi and other enemies. 



Oxygen. — The aeration of soils is of the utmost 

 importance, without it there cannot be any germi- 

 nation of seeds, and no proper growth of trees, 

 shrubs and other plants. The agencies by which 

 oxidation in soils is brought about are not only 

 air, — the chemical reactions occurring within the 

 soil, and earthworms, but as Dr. Darbishire and 

 Dr. Eussell ^ have experimentally proved, oxidation 

 is mainly, although not entirely, due to the activity 

 of microbes. The rate of oxidation does not 

 entirely depend on the amount of organic matter 

 present in the soil. Moisture is essential ; as its 

 amount increases, the rate of oxidation also in- 

 creases, until near the point at which the soil 

 becomes water-logged. The addition of calcium 

 carbonate (limestone or chalk) also increases the 

 bacterial oxidation ; and it is further stated that 



^ Report of the British, Association, 1906. 



