36 BULLETIN 353, U. S. DEPARTMENT OP AGRICULTURE. 



SUMMARY. 



The variation in moisture content in field-cured forage often gives 

 rise to errors greater in amount than the differences in yield between 

 improved varieties or different methods of culture. 



A study of the use of samples in correcting forage yields indicates 

 the following results: 



(1) Air-dried samples are a little less acciirate than oven-dried samples, biit the 

 difference is so small that the air drying of samples can be relied upon for all prac- 

 tical purposes in correcting forage yields. 



(2) Much greater extremes are found in the samples of field-ciired material than 

 in the samples of green material, indicating that replication of samples is more 

 important in the former than in the latter. 



(3) Con'ections by means of samples can be accurately made from either green or 

 field-cured material, provided care is i;sed in sampling. 



(4) Considering accuracy of results, facility of handling, and ease in figuring per- 

 centages, 5-pound samples of field-cm'ed material and 10-pound samples of green 

 material are recommended as the most desirable sizes for practical use. 



(5) Samples need not be replicated more than three times. 



(6) The percentage of moisture in the different crops at that period of growth when 

 they are ordinarily harvested for forage was as follows: Alfalfa at Chico, Cal., 75 to 

 78 per cent; average, 76.9 per cent. Alfalfa at Arlington Farm, Va., 74 to 76.5 per cent; 

 average, 75.2 per cent. Tall oat-grass and orchard-grass mixture at Arlington Farm, 

 Va., 71 to 73 per cent; average, 72 per cent. Timothy at New London, Ohio, when 

 in full bloom, average, 67.2 per cent. Sorghum at Amarillo, Tex., 70 to 73 per cent; 

 average, 71.2 per cent. These percentages are probably near the average for each crop, 

 but the fact that McKee found 85.8 per cent and Farrell an estimated 79.5 per cent of 

 moisture in alfalfa indicates that it will be impossible to establish any arbitrary 

 percentage of moisture in the green plant as a basis for correcting forage yields. 



(7) The average amount of moistin-e in field-cured material was as follows: Alfalfa' 

 22.3 per cent; timothy, 20.3 per cent; tall oat-grass and orchard-grass mixture, 29 per 

 cent; sorghum, 43.2 per cent. The moisture content of field-cm'ed material varies so 

 widely that it can not be foretold with accuracy. 



The use of the sample method in correcting forage yields would 

 greatly assist in standardizing agronomic data and do much to 

 promote greater accuracy in field tests. 



The system of correcting yield data by the use of air-dried samples 

 is of most value in succulent crops Hke sorghum and Sudan grass 

 and is of least value in fine-stemmed plants like millet, which cure 

 quickly and rather completely. 



The relation of the moisture content to the stage of development 

 in the plants was studied in alfaKa, timothy, and sorghiim. The 

 results were as follows: 



(1) Alfalfa at Chico, Cal.: Very young (12 inches high), 78.9 per cent; one-tenth 

 in bloom, 77.1 per cent; full bloom, 74.6 per cent; past full bloom, 73.4 per cent. 



(2) Sorghum at Amarillo, Tex.: Very young, 90.6 per cent; shooting for heads, 

 87.1 per cent; beginning to head, 84.8 per cent; full bloom, 80.4 per cent; seed ripe, 

 75.3 per cent. 



(3) Sorghum at Hays, Kans., varied from 89.2 per cent when very young to 73.2 

 per cent when seed was ripe, showing practically the same gradations as at Amarillo, 

 Tex. 



