256 SEEDING AND PLANTING 



Leaves, nursery refuse, bits of turf, raw humus, forest litter, and 

 similar materials, when available at little cost, can be added to 

 the manure advantageously in many instances. Lime is some- 

 times added to hasten decomposition and prevent the loss of 

 nitrogen during fermentation. Phosphate rock and kainit are 

 sometimes added to increase the phosphorus and potash. Farm 

 manures, particularly horse manure, when loosely piled out of 

 doors are liable to heat and become "fire-fanged." This causes 

 them to lose a large part of their plant nutrients, particularly 

 nitrogen. This condition can be prevented and the decompo- 

 sition hastened by building a fence around the pile and turning in 

 a number of hogs to tread it down and root it over. It becomes 

 well rotted in from 12 to 16 months and suitable even for seedbeds. 



A simple form of compost heap, suitable for the nursery, can 

 be made as follows: A layer of rich forest soil or turf, 8 to 10 

 inches in thickness, is spread over the ground. A layer of the 

 various fertilizing materials that are to be composted are spread 

 over the forest soil or turf. The pile is built up of alternating 

 layers of soil or turf and fertilizers, each layer not over 4 to 6 

 inches in thickness. A layer of rich soil, 5 to 8 inches deep, is 

 spread over the pile. The length of time required for the com- 

 post to become suitable for use depends upon the character of 

 the fertilizing materials and the rapidity of decay. A year will 

 usually suffice. 



29. The Use and Application of Fertilizers of Mineral Origin. 

 Although fertilizers of mineral origin have as yet but little use in 

 forest nurseries in the L^nited States, they can often be used to 

 great advantage in localities where farm manures are not available 

 or where they are required to improve the physical condition of 

 the soil. The more important of these materials are nitrate of 

 potash, kainit, Chilian saltpeter, superphosphates, Thomas slag, 

 wood ashes, turf ashes, lime, gypsum, sand, and clay. Lime, 

 gypsum, sand, and clay are chiefly useful in improving the physical 

 conditions of the soil. Lime also adds to soil fertility by neutral- 

 izing acids and acid compounds, promoting the formation of 

 nitric acid and nitrates, and in making other plant foods in the 

 soil more available. When lime is used in nursery practice, it 

 should be applied only to soils in which it is clearly deficient and 

 then, as a rule, in compost. 1 



1 Schlich, Wm. : Manual of forestry. 4th ed. f vol. II, p. 204. London, 1910. 



