22 



On the other hand, the checkerboard system requires about 

 200 feet more to the acre of main ditches than the parallel 

 systems, although it decreases the amount of spur ditching 

 needed by an appreciable amount, so that the average additional 

 feet per acre required under the checkerboard system is about 

 150. In New Jersey, where the amount of salt marsh to be 

 drained is so large and the obtainable funds so small, it would 

 have been impractical to use this system on account of the great 

 necessity of covering as much territory as possible. Also under 

 the Commission system in recent years it has been possible to 

 have organized maintenance gangs care for the drained areas. 



The checkerboard system would also have met with decided 

 opposition from the meadow ovvners and salt hay cutters, for 

 it makes the use of a mowing machine difficult. Salt hay cut- 

 ting is a much larger industry in New Jersey than in the vicinity 

 of Jamaica Bay, where thousands of acres of salt marsh are 

 never cut. 



In comparing the two systems, the conclusion seems to be that 

 the circulating system is more efficient than the parallel system, 

 in that it will operate under adverse conditions, but it is more 

 expensive in the cost of installation. It is especially satisfactory 

 where the meadow is so soft or where there are so many salt 

 holes that "cave-ins" are frequent and where • much trouble 

 occurs from floating sods. 



The parallel system is satisfactory where the initial cost must 

 be as low as possible and where organized maintenance exists. 



Several other ditching systems are occasionally advocated and 

 used, but they are all modifications of the two mentioned, and 

 need no separate descriptions. 



Some question has arisen as to the feasible length of ditches 

 on the salt marsh, and efforts have been made to make all ditches 

 as short as possible. This seems to be needless precaution, as 

 observations have shown that where the fall of the tide is six 

 inches or more below the bottoms of the ditches, unobstructed 

 ditches up to 2,500 or 3,000 feet long will run practically dry 

 if the outlets are satisfactory. 



