436 EXPERIMENT STATION RECOED. 



the samples as they stood, the indication being the formation of an acid. To 

 prevent this change, for the purpose of obtaiuiug more accurate results, 

 bichlorid of mercury was used as a disinfectant to arrest enzym action and 

 fermentation, but this was also found to interfere with the accuracy of the 

 method. 



The study of the formation of the sugars and starch by analyzing samples 

 harvested on different dates showed that on August 28, 1908, In every case, the 

 sucrose was high and the glucose low, that the sucrose decreased and the 

 glucose increased as the time of maturity approached, and that the total sugars 

 and starch both decreased at the time of the most rapid development. Later 

 the starch increased, but the total sugars continued to decrease, the water 

 decreasing at the same time, until September 29 when the sucrose was at its 

 lowest and the glucose generally at its highest. 



Similar work was continued in 1009. The results led the author to believe 

 that in the very immature potato the sugar may be present either as glucose 

 or sucrose, probably depending upon the meteorological conditions. It is 

 stated that in 1908 when the 10 days previous to the first digging were wet and 

 cloudy, the sugar was in the form of sucrose, while in 1909 when the 10 days 

 preceding the digging were fair, it was present almost entirely as glucose. The 

 crop of 1908 was grown on a clay loam soil, while the 1909 crop was grown on 

 a sandy soil. 



Crop rotation and fertilizer experiments with sun-cured tobacco, W. W. 

 Geeen (Virginia Sta. Bui. 196, pp. 3-20, figs. 8). — Earlier reports on these 

 experiments, which are in cooperation with this Department, have already been 

 noted (E. S. R., 22, p. 137). 



The results of the crop rotation work led to the recommendation of the 

 following 7-year rotation: Tobacco, wheat, grass, grass, corn with crimson 

 clover as a cover crop, cowpeas, and red clover. The rotation of crops in the 

 sun-cured tobacco district was found necessary and profitable. In connection 

 with this rotation work it was found that seeding grass alone in August gave 

 better results than seeding with small grain. 



The fertilizer experiments showed that phosphoric acid was needed most in 

 the soils of the sun-cured tobacco district, and that a complete fertilizer gave 

 the best returns. Potash and nitrogen were unprofitable without phosphoric 

 acid. The use of lime did not respond very perceptibly. Applications of cotton- 

 seed meal made a much finer grade of tobacco than the use of nitrate of soda, 

 but the yield was smaller. Only two-thirds as much nitrogen was found neces- 

 sary when given in the form of nitrate of soda as when applied as cotton-seed 

 meal. Heavy applications of fertilizer were found to be more profitable than 

 light applications. The use of 1,000 lbs. of 3:8:3 fertilizer per acre gave a 

 profit of $40.29, while 1,300 lbs. of a home-mixed fertilizer gave a profit of 

 fll2.17. 



Growing and curing sun-cured tobacco, W. W. Geeen (Virginia Sta. Bui. 

 191, pp. 3-l.'i, figs. 6').— Directions for growing and curing sun-cured tobacco 

 accompany a statement of the results of a fertilizer test. 



A yield of 580 lbs. of tobacco and a profit of $38.69 foUowed an application 

 of 1,000 lbs. of a ready-mixed 3:8:3 fertilizer costing $12.50 as compared with 

 1,110 lbs. and $79.92 after an application of a mixture of 1,500 lbs. cotton-seed 

 meal, 500 lbs. of acid phosphate, and 200 lbs. of sulphate of potash per acre 

 costing $32.41. " This shows more than twice the net returns from the heavy 

 application of home-mixed fertilizer" than were secured after the use of the 

 ready-mixed fertilizer. The following wheat crop also received a marked 

 benefit, 



