36 FORAGE PLANTS ANJ) THEIR CULTURE 



Similar losses were also found when wheat plants 

 grown in the greenhouse to ripeness were exposed to 

 four rainfalls in such a way that the rain after falling on 

 the plant was caught in a tray. Oat plants were also 

 subjected to a test of this sort with comparable results. 



From these experiments the conclusion is drawn that 

 plants exude salts upon their surfaces and the rain then 

 washes these salts back to the soil. 



27. Hay stacks. In the absence of barn room, hay 

 is frequently stacked in the field, especially in dry regions. 

 The shape of stacks varies greatly. If circular at base, 

 they may be conical or thimble-shaped in form, not in- 

 frequently being built so that they are largest above the 

 middle, as this will shed water from the base. In the 

 west, they are most commonly rectangular in outline, 

 higher than broad, and with the top ridge-like or less 

 commonly rounded. 



Well-built stacks are compact and the hay so laid that 

 it sheds water both on the top and sides. This is difficult 

 to accomplish with legume hays, so that stacks of these 

 are frequently covered with grass hay or straw. 



To build a good stack requires both knowledge and 

 experience. 



28. Spontaneous combustion. Under certain con- 

 ditions hay, especially of legumes, if put in a mow or stack 

 while still moist, engenders great heat, and in some cases 

 destructive fires have resulted. Several instances have 

 been recorded where the center of a mow or stack has 

 been found entirely charred when opened. Apparently the 

 only reason that prevented ignition was the absence of air. 

 There have, however, been a number of well-authenticated 

 cases where barns have been burned by spontaneous com- 

 bustion from alfalfa and from crimson clover hay. 



