186 REPORT OF THE HORTICULTURIST OF THE 
succeeding one. This would indicate that there is a clearly defined 
limit to the depth of profitable cultivation. So long as the benefit 
to the crop, through the conservation of moisture, is greater than 
the injury accruing from root laceration, the cultivation is profit- 
able; beyond this it may become unprofitable. 
The influence of the mulch in retaining water in the soil is 
especially noticeable. The mulch used in this experiment was of 
fine oat straw that had served during the preceding winter in 
covering strawberries. Its depth did not exceed one inch after it 
had become packed a little by the rains, and it was not renewed 
during the season. It appears, however, that during the dry 
weather its efficacy in retaining water was almcst double that of 
the deepest soil stirring used in this experiment, a fact which 
emphasizes the great value of mulching in its proper place. 
CONCLUSIONS. 
The results of this experiment warrant the following conclusions 
for the soil upon which it was made: 
1. That keeping the surface of the soil stirred, if only to the 
depth of half an inch, increases the water content of the first 
twelve inches to a very appreciable degree. 
2. That the deeper the tillage, at least up to four inches, the 
greater is the increase in water content. 
3. That the rate of increase diminishes as the depth increases. 
4, That a slight mulch exerts a far greater influence in retaining 
water than tillage four inches deep. 
An observation made while excavating for a lysimeter in the 
latter part of August is appropriate here, as showing the depth to 
which surface tillage affects the water content of the soil. The 
excavation was made ona dry ridge, in order to escape bottom 
water, and on one side it reached into the corner of a plat that 
had been plowed in the spring, but upon which no crop had been 
planted, and which had not been cultivated during the summer. 
The soil it was necessary to remove was very dry and hard, except 
beneath this plowed portion, where it was so much moister and 
softer that the labor of excavation was very materially reduced. 
The influence continued to be noticeable to the depth of at least 
two feet. 
