HJ4 TIM-: cn;rri;i; OK KAIIM CROPS. 



most perfect freedom. 



Deep surface plowing should he done gradually. It is 

 not wise In bring up a subsoil until (In- air has had time to 

 Jict. upon it All soils, as we have seen, contain sulphuric 

 ueid and iron, and the conihination of these substances Conn 

 a most, noxious substance vi/, sulphate of iron or copperas. 

 This is frequently found in snhsoils to which air has not 

 penetrated and when the roots of plants touch it, the crop 

 sickens, turns yellow and perishes. \\\ the admission of 

 air, with its oxygen, this noxious compound is decomposed; 

 the sulphuric acid i.> divorced from the iron, and i> .-et five 

 to he appropriated hy the crops in otlier and useful forms, 

 und the iron unites with the oxygen forming a useful suit 

 Htance oxide of iron which enters to a small extent into 

 all vegetable growth. |'or this and other reasons of like 

 import the snhsoil should he hroken up hv thesnhsoil plow; 

 hut the suhsoil should he brought to I he surface only a> il 

 has heen aete<l upon hy t he at mosphere and h\ I he manure. 

 A soil may he plowed as deeply as it. is occupied hy plant 

 food and new soil may he gradually mixed with this hv 

 gradual deeper plowing- An inch a year, brought up in 

 the fall, and left to the influences of the air and weather 

 and then mixed \\ith the oilier soil on the surface, mav he 

 safely and usefully added to the depth of the cultivated 

 soil, until .S 01- ID inches has heen enriched and titled for 

 the aliment of plants. 



A fanner intent upon the improvement of his x.il should 

 not rest until he Can safely plow the land to this depth. A 

 table previously given -hows how much fcrtili/ing matter 

 may he contained in ! inches of arahle soil over an acre. 

 When the soil has heen brought into this condition hy me 

 chanical means, then the farmer may UM- all methods for 

 making this vast store of plant food available. What miHil 

 he the maximum yield of crops has never yet heen axvr- 

 taiiud. "2 in bushels of irrain corn per acre have heen pro- 

 duced: the author has grown 1 ^> hu>hels per acre, and !!' 

 bushels per acre over a whole field, more t han once; and SO 

 bushels frequently. (! Ions of timothy hay per acre ha- 



