221 FEEDS AND FEEDING 



the Iowa Station 61 states that at 120 to 150 Fahrenheit all bacteria and 

 molds will be killed. The oxidations continue and the mass becomes hotter 

 and hotter. Finally, the hay begins to char and at a temperature of from 

 300 to 400 F. spontaneous combustion may occur and the mass burst in- 

 to flames. This generally happens a month or six weeks after the hay is 

 stored. The only way to avoid such loss is never to store hay in a large 

 mass unless it is thoroly cured. If hay in a mow or stack heats unduly 

 a day or two after storing, and pungent odors, with much vapor and gas, 

 are given off, it should be removed at once and spread out to dry. Re- 

 moving the hay later may only hasten spontaneous combustion. All that 

 can usually be done then is to compact the hay as much as possible and 

 cover it with other material so as to keep the air out. 



336. Measurement and shrinkage of hay. In estimating the amount of 

 hay in a stack or mow, it is necessary first to compute the volume in 

 cubic feet. Kules, which differ quite widely, are employed in various 

 parts of the country in reckoning the tonnage from the volume in cubic 

 feet. One often used is that after settling for 30 days it takes 512 cubic 

 feet (which makes an 8-foot cube) to make 1 ton. When the hay has been 

 in mow or stack for 5 or 6 months, 422 cubic feet is considered a ton, and 

 for hay a year or more old, 343 cubic feet (which makes a 7-foot cube). 

 Often it will take 580 cubic feet or more to make a ton of hay which has 

 been in the stack only 30 days or less. 



The volume of hay in a mow may be readily computed, but it is more 

 difficult to determine the volume of a stack. Several rules for estimating 

 this have been suggested, that worked out by the United States Depart- 

 ment of Agriculture probably giving the most accurate results. This is 

 as follows 62 : 



The volume of an oblong stack in cubic feet may be found by using the 

 following formula : 



FxOxWxL= Volume 



In this formula F is a fraction which depends on the shape of the stack, O is the 

 "over" (i. e., the distance from the base on one side of the stack, over tihe stack, and to 

 the base on the other side) , W is the width, and L is the length of the stack. The val- 

 ues of F for stacks about three-fourths as high as they are wide are 0.25 for narrow or 

 triangular stacks, 0.28 for medium full stacks, and 0.31 for full and rounded stacks. 

 Where the height and width are about equal, F is 0.28 for narrow stacks, 0.31 for me- 

 dium full stacks, and 0.34 for full stacks. Where the height is about one and one-fourth 

 times the width, F is 0.31 for narrow stacks, 0.34 for medium full stacks, and 0.37 for 

 full stacks. 



Hay stored in the mow will shrink in weight, due to drying out, and 

 also to fermentations taking place during the sweating process, in which 

 nutrients are broken down into carbon dioxid and water. The shrinkage 

 will vary, depending on the water content of the hay when placed in the 

 mow, and may reach 20 per ct. or over. When hay is stacked the shrink- 

 age is greater, since the outside of the stack is exposed to the weather. A 

 stack 12 feet in diameter has about one-third of its contents in the surface 

 foot. 



"Iowa Circular 36. U. S. D. A., Off. of Sec., Cur. 67. 



