Recognizing the fact that the seed-bed is the home of the plant and 

 that from the seed-bed the plant receives its food, it stands to reason 

 that it must contain humus in abundance, if the plant is supplied with 

 food; hence, in plowing, great care should be exercised in gauging the 

 depth, for we know that the subsoil is deficient in humus and that if it is 

 brought to the surface in gi*eat quantities, the fertility of the seed-bed is 

 materially diluted or weakened ; therefore, in our efforts to secure a 

 greater feeding area for the plant roots by plowing deep, we are sure to 

 do harm unless the depth is increased gradually and as each slice of 

 new soil is brought to the surface, organic matter, preferably barnyard 

 manure, is thoroughly mixed with it. This, however, can be prevented 

 by using the right type of plow which will be referred to later. By grad- 

 ually increasing the seed-bed one-half inch each j'^ear and keeping in 

 mind the absolute necessity of supplying humus in sufficient quantities 

 for the new soil and to maintain the required content of the old soil, th9 

 farmer can, with no danger of impairing his crop, in a few years attain a 

 depth of ten, twelve or even fourteen inches. 



Do Not Till Deep 



If the subsoil is sand or gravel, it is not advisable to bring it to the 

 surface nor plow too near that formation. Sand or gravel will not 

 retain water in suspension; hence, in such soils it is better to form, as far 

 as possible, a compact plow sole which will, in a measure, prevent the 

 percolation of rainfall. 



Sandy Soils 



In sandy soils, deep plowing is admissible if an abundance of humus 

 or organic matter is provided; otherwise, the water will percolate below 

 the reach of the roots, carrying with it fertility. 



The deeper a sandy soil can be cultivated, providing an abundance of 

 organic matter is furnished, the more certain is the soil to maintain a 

 sufficient amount of water to mature the plant. 



Virgin Soils 



Virgin soils should not be plowed below the line of humus. However, 

 subsequent plowing can be increased in depth the same as in older culti- 

 vated lands provided organic matter is supplied. 



Benefits of Deep Tillage 



The benefits of deep tillage are many, provided all of the requirements 

 heretofore mentioned have been complied with. 



It is obvious that the plant roots require room. Soil bacteria, which 

 perform the function of converting elements into compounds, require air. 



Plants require food and most of it is secured from the seed-bed, and 

 plants require water; hence, to meet all of these requirements, the seed- 

 bed should be deep, of good tilth and in a good sanitary condition. 



