30 



Campbell's 1902 Soil Culture Manual. 



vapor and pass up through the mulch. The forming of a crust under 

 these conditions, as is also true on the surface, is largely the result of the 

 salts and alkalies that are in a soluble condition, while the soil below is 

 wet. As the moisture from the surface begins to evaporate it leaves these 

 chemicals deposited in the little spaces between the soil particles practi- 

 cally cementing them together. As the process goes on, the moisture line 

 lowering, the surface becoming dry an eighth, quarter, or half inch, possi- 

 bly an inch in depth and is filled with these chemicals which is quite de- 

 trimental in the free circulation of air. 



EXPERIEISCE WITH AN ORCHARD. 



We cannot impress this point more fully upon your mind than by 

 relating our experience with the orchard at the Pomeroy Farm during the 

 season of 1901. We began our harvest just as the extreme hot weather and 

 high winds from the south set in. About seven days before commencing 

 harvest we had cultivated the orchard with the Acme harrow. Our mulch 

 was a good depth and the moisture condition perfect just beneath it. The 

 high winds and extreme heat delayed us materially in our harvest, and 

 sixteen days had elapsed before we were able to reach the orchard again, 

 as help was scarce and our grain shelling badly from the fact we could not 

 get at it. We attempted the cultivation on the 17th day after the last cul- 

 tivation with the Acme harrow, but the nine days of excessive heat had so 

 heated the mulch as to draw the moisture from the solid soil beneath un- 

 til a crust of fully half an inch had formed. The crust had become very 

 hard in this time and its resistance was so great the Acme could not break 

 it. At about this time, or within a day or two, we noticed the color of the 

 leaves on our trees began to change to a lighter cast. Not until noticing 

 this did we give special attention to the soil condition, but noting this crust 

 under the mulch we immediately ordered one-half the orchard double disced 

 with instructions to cut a full inch and a half deeper and awaited results. 

 About the fourth day there was a perceptible change in the color of the 

 leaves on the portion disced, and on the seventh day the difference was 

 perceptible to any one. The leaves again took on their bright green glossy 

 appearance, and new leaves coming out then we ordered the balance dou- 

 ble disced. We had nearly three weeks of extreme heat after this, and yet 

 during all of that time the trees were pushing out new leaves, and at the 

 close of the dry period were to all appearance in as healthy and thrifty con- 

 dition as at any time during the entire growing season. The changing of 

 the color of the leaves in this way was not due to a lack of water at the 

 roots, but simply the lack of air. 



We had a similar experience, but more clearly illustrated, in the cul- 

 tivation of corn in Cheyenne county, northwest Kansas, in 1898. This de- 

 monstrates very clearly the great importance of being exceedingly cautious, 



