EXTENSION COURSE IN SOILS. 77 



in them and do not come in contact with a sufficient amount of the 

 soil to supply their needs. This is particularly true when fine- 

 rooted crops are to be grown. The use of heavy rollers to firm such 

 soil results in great improvement in this respect. Not only does the 

 rolling and firming of the soil have the effect of bringing the roots in 

 direct contact with a much larger area of soil surface, but it permits 

 a more rapid conduction of the heat from the surface downward. 

 In this way the lower layers of the soil are warmed, and this greatly 

 increases the growth of the roots and promotes bacterial changes, 

 such as nitrification, to which the fertiUty of the soil is in part due. 



Crops for marsh soils. — A great variety of crops have been grown 

 on marsh soils on account of their large supply of nitrogen. They are 

 especially adapted to crops which produce rank growth and require 

 large quantities of this element, such as corn, cabbage, rape, turnips, 

 beets, and potatoes, though, of course, the quahty of sugar beets and 

 potatoes grown on such land may not be quite so good as when 

 grown on upland soil. Since marsh soils as a whole are apt to be cold 

 and affected by local frosts, care should be taken in the selection of 

 crops, especially in northern climates. Here corn and potatoes, for 

 example, might be out of the question. On the other hand, cabbage, 

 rape, turnips, hay, of which a mixture of timothy and alsike clover 

 is perhaps the best, and grain to a limited extent when proper care is 

 taken may be grown to advantage. 



EXERCISES. LESSON X. 



PROBLEMS. 



1. A man had 40 acres of marsh land which produced on an average 1 ton of wild 

 grass per acre, valued at about $3 per ton. He spent |1,000 in draining it. Now 

 those 40 acres raise corn averaging 15 tons of silage corn per acre, valued at at least $3 

 per toil. Determine this man's interest on his investment. 



2. Fifteen tons of manure per acre were applied on a drained peat soil. How many 

 pounds of phosphorus and potassium were applied? How big a crop of corn will this 

 amount of potassium supply? 



3. Two hundred pounds per acre of muriate of potash were applied to a muck soil. 

 What was the cost of this application at $46 per ton, and how many pounds of potassium 

 per acre were applied? (See table 24, p. 157, Ref. No. 5.) 



4. Compare the value of the manure applied in problem 2 with the cost of the potash 

 fertilizer in problem 3. 



5. A portion of a peat marsh was treated with maniu-e at the rate of 15 tons per acre; 

 another portion was treated with an application of 400 pounds of muriate of potash per 

 acre, costing $47 per ton. The first year the maniued portion produced 10.5 tons of 

 silage (green) corn per acre, and the second year a yield of 6 tons was seciued with- 

 out any further treatment. On the potash portion the corn averaged 14 tons the first 

 year and 14 tons the second year, without further treatment. Compare the results pro- 

 duced with the cost of manure and fertilizer in this case. 



6. On another marsh (muck), an application of a mixture of miuiate of potash at the 

 rate of 200 pounds per acre and rock phosphate at the rate of 800 pounds per acre pro- 

 duced 12.5 tons of silage corn per acre. An application of 25 tons of manure on 



