THE SHRINKAGE OF MARKET HAY. 15 



Experiments 17 made in California showed that, in one instance, 

 alfalfa cut at 10.22 a. m. lost 39.1 per cent of the water in an hour 

 and a half, and that by 4 p. m., about 6| hours later, it had lost 63.7 

 per cent of its total water content. Timothy, in Ohio, lost 30.4 per 

 cent of water from noon until 5 p. m., when the temperature at noon 

 was but 76° F., indicating that the conditions were not very favor- 

 able for curing. 



The Iowa station 18 found that different plats of alfalfa cut and 

 hauled on the same day may vary as much as 20 per cent in shrink- 

 age, the hay handled early in the day possibly containing twice as 

 much moisture as that hauled in the afternoon. 



A comparatively small difference in the length of time hay remains 

 in the field, in the swath, and in the windrow after it has cured suffi- 

 ciently to be stored may make a decided difference in the amount 

 lost by shrinkage in the barn or stack. 



At the Utah station 19 two lots of clover hay put up the same day 

 showed a difference of 14.45 per cent after being stored nine months. 

 The hay stored in the barn lost 3.75 per cent and that stacked gained 

 10.7 per cent. 



The knowledge which enables the farmer to tell when hay has lost 

 just enough water to make it safe to put it into barn or stack is 

 valuable and indeed essential, while a knowledge of the exact per- 

 centage of shrinkage that takes place during field curing is neither 

 necessary nor helpful to the average haymaker. 



LOSS OF DRY MATTER. 



A part of the so-called loss in hay, through shrinkage, is sometimes 

 due to an actual loss of dry matter. The accepted usage of the term 

 "lost" to denote both loss in water content and a reduction in the 

 amount of dry matter in hay after being in storage for some time is 

 somewhat misleading. It is quite proper and self-explanatory to 

 say that hay has lost a part of its water content, for this is exactly 

 what has happened — the water has actually been taken out of and 

 away from the hay. But when it is said that there has been a loss 

 of dry matter during the shrinkage of hay, the impression may be 

 given that the dry matter is also carried out of and away from the 

 hay. As a matter of fact, dry matter is "lost " in a more roundabout 

 way than is water, which evaporates whenever the percentage of 

 water in the air is lower than that in the hay. Furthermore, once 

 gone, dry matter can not return, as water may. 



Water is a comparatively simple compound and readily changes in 

 form as the temperature of the air varies. The dry matter of hay, 



I' U. S. Department of Agriculture Bull. 353, 1916. p. 28-30. 



is Iowa Agricultural Experiment Station Bull. 137, 1913. p. 57-58. 



19 Utah Agricultural Experiment Station, Fourth Annual Report, 1893. p. 35-37. 



