ANNUAL REPORT, 1947-48 11 



ers are now afraid to use chloropicrin for soil sterilization and, owing to the 

 general unavailability of steam sterilization, they have no satisfactory substitute. 



The object of this experiment was to determine whether late fall sterilization 

 of tobacco seedbed soil with chloropicrin would cause poor germination and 

 growth of tobacco seeded the following spring. Other factors affecting the pro- 

 duction of tobacco seedlings were also studied. 



Four seedbed plots, 30 feet long and 6 feet wide, each received 25 pounds of a 

 8-4-8 tobacco fertilizer: two in late October^ 1947, and two shortly before seeding 

 time in the spring of 1948. One of each pair of plots was sterilized with chloro- 

 picrin in late October, 1947; the other two were not sterilized. The soil tem- 

 perature of the plots was about 50° F. at the time of treatment with chloropicrin 

 and remained low for the rest of the fall. The observed results were as follows: 



Plot I. Fall Fertilized and Sterilized. The germination of seed was very 

 good; the seedlings grew well and weed control was good. The productivity as 

 well as the weed control in this plot was equal to that obtained in another seedbed 

 which had been sterilized with chloropicrin and fertilized early in September. 

 At that time the temperature of the soil was well above 60° F. and remained so 

 for a considerable time. 



Plot II. Fall Fertilized but Not Sterilized. The stand and growth of seedlings 

 were good but not so good as on Plot I. The weed infestation was heavy. 



Plot III. Fall Sterilized and Spring Fertilized. The stand of seedlings was 

 very poor with no plants at all occurring in large areas. The seedlings grew poorly 

 throughout the season. The weed control was good but less effective than on 

 Plot I. Possibly the poor stand of tobacco seedlings offered less competition to 

 those weeds which survived the sterilization, and thus the weeds grew more 

 vigorousl3\ 



Plot IV. Spring Fertilized but Not Sterilized. The stand of tobacco seedlings 

 and their subsequent growth was poor throughout the season. Weed infestation 

 was heavy but somewhat less than on Plot II. 



The general conclusions and practical applications of these observations are: 

 Chloropicrin, although applied late in the season, was apparently not the cause 

 of the seedbed failure in this trial. The failure of the seedbed was attributed to 

 effects of the spring application of the fertilizer. It is believed that tobacco seed- 

 beds should be fertilized in the fall or at least a considerable time before the seed- 

 ing if the fertilizer is applied in the spring. 



Fertilizer Placement for Potatoes. (C. V. Kightlinger and H. M. Yegian.) 

 It is the purpose of this project to determine how different ways of applying 

 fertilizer affect the growth and yield of potatoes. 



Fertilizer of 5-10-10 formula was used at the rate of 2200 pounds per acre 

 and was applied in three ways: all banded; half banded and half broadcast; and 

 all broadcast. The broadcast fertilizer was harrowed into the soil thoroughly 

 before the potatoes were planted. The banded fertilizer was applied in the usual 

 manner by the potato planter. 



The plots were one-twelfth acre in size and were replicated four times. Green 

 Mountain potatoes were planted about the middle of May and were sprayed with 

 Bordeaux mixture at weekly intervals froin the middle of June until frost killed 

 the vines in late September, with DDT and nicotine used as needed to control 

 insects. 



\ Plots where the fertilizer was all banded produced much better growth of 

 vines and much larger yields of potatoes: 23 percent more marketable potatoes 

 than the plots on which the fertilizer was half banded and half broadcast, and 51 

 percent more than the plots on which the fertilizer was all broadcast. Also, con- 



