CROPS AND SOIL IMPROVEMENT 



determined. It may be necessary to reduce or 

 increase the grade at some point to get proper 

 depth in a depression or to save cutting when pass- 

 ing through a ridge. 



Cutting the Trenches. There are ditching- 

 machines that do efficient work. The best are 

 costly. Most of the work on farms will continue 

 to be done with ditching-spades. The ground 

 should be moved when wet, so that labor can be 

 saved. 



A line should be used to secure a straight side 

 to the trench. The grade should be obtained by 

 means of a system of strings. If two light poles 

 be pushed into the ground at each 100-feet sta- 

 tion, one on either side of the proposed trench, 

 and a string be drawn across at a point 5J feet 

 above the bottom of the proposed trench, these 

 strings will be in line on a grade 5j feet above the 

 grade the drain will have. As the cut at the sta- 

 tion is known, the height of the string above the 

 top of the stake is easily determined. These 

 strings will reveal any inaccuracy in the survey. 

 The workman can test every part of the bottom of 

 the trench by use of a rod 5| feet high, the top end 

 being exactly in line with the strings when the 

 lower end is placed on the correct grade of the 

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