OTHER SOIL AMENDMENTS 355 



Another effect of salt is to conserve and distribute 

 soil moisture. Its conserving action is probably due to 

 an increase in the density of the soil-water solution re- 

 tarding transpiration. The film movement of water is 

 likewise increased by the presence of salt in the solution, 

 and in this way the upward movement of bottom water 

 is facilitated, and the supply within reach of the roots 

 maintained in time of drought. 



It is not all soils, however, that are benefited by salt, 

 its usefulness not being of such wide application as that 

 of lime. Certain crops, as previously mentioned (page 

 340), are injured by the presence of chlorine. 



226. Muck. The effect of muck is to change the 

 structure of soils; making heavy clay soils lighter and 

 more porous, and binding together the particles of a 

 sandy one. Both classes of soils, but particularly the 

 sandy type, have a greater water-holding capacity after 

 treatment with muck, owing to its great absorptive 

 power, amounting to 70 per cent or more of its own 

 weight. (See page 153.) It is to its content of organic 

 matter that the physical effects of muck are due. 



Muck contains 1.0 to 2.0 per cent of organic nitrogen, 

 calculated to dry matter which does not readily undergo 

 ammonification. The addition of farm manure which 

 ferments readily, and of lime, serves to hasten ammoni- 

 fication. Its use as an absorbent in the stable fits it well 

 for use on the land. 



Very large applications of muck are necessary when 

 it is used to improve the structure of the soil. From 

 ten to forty or fifty tons per acre are frequently 

 applied. 



