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leaching downward ; there is far more fear of its leaching 

 upward by evaporation into the air. It can never go too 

 deep for the use of plants ; that is an old, and as I had 

 hoped, a completely exploded agricultural superstition, — 

 a superstition that I trust deep ploughing will soon bury 

 so completely that it shall never be brought up again. 

 Fourthly : deep, thorough tillage, by lightening up the 

 soil, allows the warm sun to thrust down his quickening 

 rays into its bosom. Fifthly : it thus invites the air to 

 circulate among its particles, and impregnate them with 

 nutritious elements ; and when we reflect that the air 

 not only holds in its embrace all the various gases that 

 supply food to the vegetable world, such as carbonic acid, 

 phosphoric acid, &c., — but that it is, in a very large 

 measure, made up of nitrogen, the principal element of 

 that essential of all manures, ammonia — for ammonia is 

 nothing but the nitrogen of the air with a little hydrogen 

 from the water — we shall see what a vastly important part 

 the air plays in feeding plants. Indeed, it is their ca- 

 pacity for taking up ammonia and other stimulating and 

 nourishing gases, that gives to lime and absorbent earths 

 generally, very much of their value ; thus we have the 

 sulphates, carbonates, phosphates, nitrates, ascetates of 

 lime, &c. Sixthly : in severe droughts, such deep til- 

 lage not only prevents the earth from baking hard, but 

 as the air always contains moisture, as seen in the drops 

 condensed even in the dryest weather on stones and ves- 

 sels of cold water, — its circulation through the soil de- 

 posits the moisture among the particles of earth and 

 sand and gravel ; — and thus, in times of long protracted 

 droughts, as you well know, a light soil of sandy loam 

 suffers far less than one of heavy clay. The second grand 

 essential to bountiful crops is the preparation and the ap- 

 plication of manures. I remember my old grandfather — 

 peace to his ashes ! used to tell his gardener to take good 



