142 EXPERIMENT STATION RECORD. [Vol. 41 



the first three stages of growth. An average yield of 45.6 bu. per acre was 

 secured without irrigation. Where only one irrigation was given the best 

 results were secured from an application made at the five-leaf stage and 

 where two irrigations were given at the five-leaf and boot stages. Where 

 only one irrigation was omitted during the different stages of growth, that 

 made at the dough stage was omitted to the best advantage. Omitting irri- 

 gations at either the bloom or the dough stage or both resulted in higher 

 yields of grain than when applications of water were made at all four stages. 

 In general the first irrigations were found to be of most value to the crop, 

 and the second next in order. Applications of water made after seeding but 

 before the grain was up decreased the yield. 



The ratio of gi'ain to straw, the height of the plant, the amount of tiller- 

 ing, the weight of the kernels, and the size of head were all affected by the 

 irrigation treatment. Irrigation, especially at the later stages of growth, 

 always retarded maturity. Small applications of manure Increased the yield 

 of both grain and straw, but large amounts caused excessive loss of grain 

 through lodging. Twenty acre-in. of water spread over 4 acres of land pro- 

 duced more than three times as much grain as where it was all used on one 

 acre. Under climatic conditions prevailing at Logan, the natural precipita- 

 tion is said to have been sufficient to produce over 70 per cent of the maxi- 

 mum yield. Finally, these experiments are held to indicate that under the 

 conditions described the best practice in irrigating oats is to make 3 applica- 

 tions of water of about 5 in. each, beginning when the plants are from 6 to 

 8 in. high and terminating with the blooming period. 



Potato studies, C. D. Woods (Maine Sta. Bui. 277 {1919), pp. 17-32).— This 

 bulletin comprises a discussion of the food value and mineral content of Maine 

 grown potatoes, the utilisation of potato pomace, ridge and level culture for 

 potatoes previously noted (E. S. R., 25, p. 529), and a continuation of observa- 

 tions on nitrogenous fertilizers for potatoes on Aroostook farm and on the 

 eifect upon the potato crop of omitthig potash fertilization (E. S. R., 39, p. 334). 



A compari.son of analyses of Maine grown potatoes with similar analyses of 

 potatoes from other American sources is held to indicate that Maine potatoes 

 contain approximately 1.5 per cent more dry matter than all other American 

 potatoes. .Spraying potatoes with Bordeaux mixture has resulted in an 

 increase both in the yield of marketable tubers and in the starch content. 

 Steaming potatoes appeared to have little effect on the composition of the dry 

 matter. In feeding experiments with sheep in which raw and cooked potatoes 

 were compared, the dry matter, organic matter, and the starch of the nitrogen- 

 free exti'act were found to be somewhat more completely digested in the cooked 

 than in the raw material. Similar tests with pigs resulted in a gain of 60 lbs. 

 each in 44 days for pigs fed raw potatoes as compared with a gain of 67 lbs. 

 for those fed steamed potatoes. 



Based on the results of an analysis of the ash of Maine grown potatoes, it is 

 estimated that a 2.i0-bu. crop weighing 150 cwt. would remove 56 lbs. of ammo- 

 nia, 20 lbs. of phosphoric acid, 72 lbs. of potash, and 1.5 lbs. of lime fi'om 

 the soil. 



The composition of potato pomace, left as a residue from the manufacture of 

 potato starch, is compared with that of potatoes and the conclusion i-eachod that 

 under present conditions its profitable utilization in this country is not possible. 



Fertilizer tests begun in 1914 to determine the best source of nitrogen for 

 potatoes in Aroostook County were discontinued w'lth the 1918 experiments, the 

 results of which confirmed the earlier findings. It is stated that there is appar- 

 ently little choice in the form of nitrogen to be used on potatoes In this region, 

 and it is suggested that in the fertilizer employed one-third of the nitrogen be 



