140 EXPERIMENT STATION RECORD. [Vol.43 



progress since 1914, wei-e conducted to determine the effects of an excessive 

 amount, of a single fertilizer element on jield, keeping quulities, texture, 

 quality, and color of the sweet potato. 



Six ^-acre plats on a Cecil clay loam soil, planted with Myers Early sweet 

 potato, were treated annually with the following quantities of fertilizer per 

 acre : Plat 1, 24 tons barnyard manure ; plat 2, 2,100 lbs. 16 per cent, acid phos- 

 phate; plat 3, 900 lbs. sulphate of potash; plat 4, 1,500 lbs. nitrate of soda; 

 plat 5, 1,800 lbs. complete fertilizer; and plat 6, uo fertilizer. During the G- 

 year period, 1914-1919, the yields generally declined. The plat receiving 

 barnyard manure stood first in yield the first 2 years, and the plat receiving 

 the complete fertilizer stood first the remaining 4 years of the period. For the J 

 entire 12-year period, beginning with 1908, the greatest average yield was^ 

 secured from the complete fertilizer plat, the barnyard manure plat standing a 

 close second. The increases in yields over the check plat showed that these 

 heavy applications had not been profitable. 



In 1919 plat 4 was divided into 2 equal parts, 1 receiving the usual appli- 

 cation of nitrate of soda and the other the same amount of nitrogen in the 

 form of sulphate of ammonia. The part treated with sulphate of ammonia 

 yielded 40.36 bu. more per acre than was secured on the part treated with 

 nitrate of soda, this increase being considered due possibly to an unfavorable 

 action of a residue of sodium in the soil resulting from 11 consecutive annual 

 applications of that substance. The use of sulphate of ammonia also seemed to 

 have reduced an infection of black rot and to have improved greatly the 

 mechanical condition of the soil where it followed nitrate of soda. 



The plats receiving large amounts of nitrogenous fertilizers gave potatoes of 

 a lighter yellow color and a somewhat poorer flavor than those produced on 

 the other plats. The acid phosphate plat and the check plat produced potatoes 

 of the best quality and finest texture. Potash seemed to have very little in- 

 fluence in this connection. 



In storage tests the potatoes from the check plat showed thehighest average 

 percentage keeping through the winter, but results in general varied so that 

 definite conclusions regarding the relation of fertilizer to keeping qualities are 

 not drawn. In similar test in 1915-16 with sweet potatoes grown for the first 

 time on an area of Cecil clay loam and one of Cecil sandy loam, red and gray 

 soils, respectively, the amount of rot on March 1 was 12.28 per cent in the 

 crop from the red soil and 4.61 per cent in the one from the gray soil. A study 

 of the loss in weight during storage from November 5 to IMarch 1 showed an 

 average total loss in the sweet potatoes from the 6 differently treated plats of 

 16.6 per cent, while the average loss in moisture was only 3.73 per cent. It is 

 pointed out that the loss of moisture does not indicate the actual loss in weight 

 of sweet potatoes in storage, and that the difference here shown is doubtless 

 due to the breaking down of carbohydrates and the resultant evolution of 

 carbon dioxid. 



Cooperative fertilizer work with other southern stations resulted at this 

 station, where sweet potatoes were grown in 1919 on a quite fertile Cecil 

 clay loam soil treated with different combinations and amounts of acid phos- 

 phate, sulphate of potash, cottonseed meal, and sulphate of ammonia, in th( 

 best yield from the 8 : 3 : 3 formula, closely followed by 8 : 3 : 6 and 8:6:6 formu- 

 las of phosphoric acid, nitrogen, and potash, respectively. The yields on tb( 

 check plats were considerably lower than those on the plats which had receivei 

 fertilizer treatment. 



Sweet potato culture and storage in New Jersey, R. W. DeBatjn {Neh 

 Jersey Stas. Circ. I14 (1919), pp. 3~31, figs. 19). — This circular is a popula 



