22 BULLETIN 353, U. S. DEPARTMENT OF AGEICULTUEE. 



lower than the field weights, even when the sorghum had been curing 

 through seven weeks of good drying weather after harvest. Tlie dif- 

 ferences in field-cured and computed air-dry weights for different 

 varieties and different dates of planting varied from minus 3.7 per 

 cent to plus 31.3 per cent. It would seem, therefore, that maturity 

 at harvest, size of shock, and succulence of the variety are factors 

 affecting the moisture content of field-cured sorghum almost as much 

 as different lengths of drying periods. At AmariUo, Tex., the differ- 

 ence in the percentage of moisture in field-cm'ed material of Red 

 Amber sorghum and air-dry samples of the same varied from 12 to 

 33 per cent, while the total moisture in the samples varied from 35.8 

 to 55.7 per cent, as determined by oven drying. Such differences are 

 enough in many instances to change the conclusions of the value of 

 different methods of treatment or different dates of planting. 



Sudan grass. — At Hays, Kans., after Sudan grass had been cured 

 three days, the field weights were 25 to 40 per cent greater than the 

 computed air-dry weights based on samples, and there was 21 to 40 

 per cent difference after a similar period of curing at Chilhcothe, Tex. 

 Many of the phenomenal yields of Sudan grass and sorghum that are 

 reported by newspapers can be explained in part by this excessive 

 moisture content. 



Alfalfa. — The computed ah-dry weights of alfaha at Chico, Cal., 

 were 10 to 15 per cent less than the field-cured weights, while at Hays, 

 Kans., in good curing weather, there was a difference of only 2 per cent. 



Different methods of culture affect the moisture content quite 

 decidedly, as shown with alfaha at Chico, where in the May 15 cutting 

 the hay from drilled plats showed only 10.9 per cent loss in air drying, 

 while in the 35-inch rows the loss was 24.3 per cent. Cuttings of 

 ahaha made at different stages of maturity can not be compared 

 accurately unless they are checked by the sample method. The 

 difference in moisture content of the field-cured material has been 

 found in a number of instances to be as great as 30 per cent. 



Millet. — Of all the crops tested, millet showed the least difference 

 between the air-dried and the field-cured material. The loss at 

 Hays, Kans., averaged about 9.3 per cent. 



RELATION OF THE STAGE OF GROWTH OF FORAGE PLANTS TO THEIR 



MOISTURE CONTENT. 



It has long been known that plants when young contain a larger 

 percentage of water than they do when mature, but no great amount 

 of data on this point, even for our principal crop plants, is to be 

 found. A compilation ^ of all the data available on this subject 

 indicates the average percentage of moisture in alfalfa to be as follows : 



1 Vinall, H. N., and McKee, Roland. A digest of literature relating to the moisture content and shrink- 

 age of forage. In Jour. Amer. Soc. Agron. , v. 8, no. 2, 1916. 



