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N. T. NELSON and P. J. ANDERSON
Nowhere in the world does tobacco receive so expensive a ration of fertilizer as in New England. About one-third of the entire cost of producing tobacco here is the fertilizer item. Aside from the heavy cost, consideration of the fertilizer problem is extremely important because its composition affects the quality as well as the yield of cigar leaf. Yet, despite its vital importance to the tobacco grower, the investigation of commercial fertilizers for tobacco has received very scant attention from the experiment stations of New England. In the annals of tobacco growing in the Connecticut Valley, extending back for more than a century, there are found records of only two sets of fertilizer experiments. These two classical experiments were conducted thirty years ago at about the same time by Goessmann' in Massachusetts and Jenkins2 in Connecticut. Conditions have changed so much in the last thirty years, both in fertilizers and in tobacco growing, that a considerable part of the conclusions from these experiments may not be applicable to present times. There is need for a reworking of the whole field of commercial fertilizers for tobacco.
There have been numerous fertilizer tests for tobacco in other sections of the country, but the results are of little value to the Connecticut grower because the type of tobacco grown is not the same, the soil and climate are different and the New England system of continuous cropping is different from that followed in other sections.
* The fertilizer experiments at the tobacco station at Windsor, were begun in 1922 by Dr. G. H. Chapman, and carried out under his direction until his resignation August 1, 1923. From that time until April 1924, they were continued by C. M. Slagg, and after April 1, by Dr. N. T. Nelson, physiologist in charge. These changes of administration have been unfortunate for the continuity of the experiments and have resulted in considerable loss since the data were recorded in different ways and are not supplemented by actual knowledge of their progress on the part of the present administration.
Since a considerable mass of data has accumulated in the files it, as seemed best to publish all of it that is of significance in order to have on record all that has been done. With some modifications and additions the experiments are being continued and it is hoped that the data obtained from them will be published annually in the future. The data on the experiments of 1922 and 1923 are taken entirely from the reports of Dr. Chapman and Mr. Slagg and the present writers wish to give to them all credit for the work done.
1 Goessmann, C. A. On field experiments with tobacco in Massachusetts. Mass. Agric. Expt. Station. Bulletin 47:1-31, 1897.
2 Jenkins, E. H. Experiments in growing tobacco with different fertilizConn. Agric. Expt. Station Report 16:1-35, 17:112-114, 18:254284, 19:128-156, 20:285-333, 21:230-256 (1892-1897).
Limitations of available space and time to devote to it made it necessary to restrict the experiments at the beginning to an attempt to solve only a few of the problems involved. The experiments were divided into series as follows:
Nitrogen series. Comparison of different carriers of nitrogen. Phosphoric acid series. Comparison of different quantities of phosphoric acid.
Potash series. Comparison of high grade sulfate of potash with double manure salt.
Manure series. Comparison of different kinds of manure. Fractional application series. Comparison of fertilizer applied all at once with the same amount, or less, divided between several applications.
6. Sulfur-chlorine-magnesium series. The purpose of this experiment was to determine the effect of these elements on the tobacco.1
In the following pages each of these series is followed separately throughout the three years of the experiment.
The tests in this series were designed to answer these questions: 1. Can all of the nitrogen be furnished to the plant from mineral carriers, nitrate of soda, nitrate of potash and sulfate of ammonia?
2. Can one-half of the nitrogen be supplied from these mineral sources, the other half being from cottonseed meal and castor pomace? 3. Can one-half of the nitrogen be supplied to advantage in dry ground fish?
4. Can one-half of the nitrogen be supplied in tankage?
The advantage to be sought through the substitution of mineral for the organic sources of nitrogen is reduction in the cost of the fertilizer since the inorganic sources are only about one-half as expensive as the organic sources. In the case of fish, it was hoped also that there might be an improvement in the quality of the leaf It is the general belief among tobacco growers that the use of inorganic sources of nitrogen produces tobacco of poor quality. In Dr. Jenkins' experiments it was found that where castor pomace was compared with a ration in which one-half of the nitrogen was supplied by pomace and one-half by nitrate of soda," the latter fornula did not produce tobacco of as good quality as where castor pomace alone was used, but the yield was increased. In his experiments he also found that the use of fish scrap as the only source of nitrogen reduced the yield but gave a superior quality. not try fish in combination with other sources of nitrogen.
1 This series in cooperation with the Office of Tobacco Investigations, United States Department of Agriculture. Not reported on in this
2 Since the nitrate of soda was applied to the growing crop as a side dressing it is not possible to judge whether the results were due to mineral nitrogen or to fractional application.
The soil in the field on which the tests were made is Hartford sandy loam, and is fairly uniform in texture, drainage and fertility. It was laid out in plots of 1/40 acre, each containing four rows. Only three rows of each plot however, were harvested for the test because the fourth row was on the border and feeding from plots on each side of it treated in different ways. The whole series of seven plots was in triplicate making a total of twenty-one plots. All fertilizers were applied broadcast at one application about one week before setting. Rows were three feet four inches apart and the plants eighteen inches apart in the row. The variety of tobacco was Havana seed and all plots were set on the same day with plants as nearly uniform as could be obtained. The tobacco was primed in 1922 and 1923 but stalk cut in 1924.
After consultation with many growers in the Connecticut Valley and a careful study of previous field experiments, it was decided that a fertilizer containing approximately 260 lbs. ammonia; 225 lbs. phosphoric acid; and 240 lbs. potash to the acre would furnish ample quantities of these plant nutrients for an acre of tobacco. These amounts were considered as a basal ration in this experiment. Although such amounts of plant food materials are greatly in excess of that removed from the soil by the plant, farm practice in the Connecticut Valley has shown that the above quantities grow a good crop of tobacco. Accordingly, all the plots of this series received approximately the same number of pounds of the above plant nutrients per acre.
The fertilizer treatment of the seven plots was as follows:
BASAL RATION. 1-7 OF THE NITROGEN IN A MINERAL OR
PLOT N2 ONE HALF NITROGEN IN INORGANIC CARRIERS (SODIUM NI
TRATE AND AMMONIUM SULFATE*). THE BALANCE OF
*These two materials used in amounts which theoretically would
not change the soil reaction.
ALL NITROGEN IN MINERAL CARRIERS (SODIUM NITRATE
PLOT N4 ONE HALF NITROGEN IN MINERAL CARRIERS (POTASSIUM NITRATE AND AMMONIUM SULFATE*). THE BALANCE OF NITROGEN IN COTTONSEED MEAL AND CASTOR POMACE.
PLOT N5 ALL NITROGEN IN MINERAL CARRIERS (POTASSIUM NITRATE AND AMMONIUM SULFATE).
PLOT N6 ONE HALF NITROGEN FROM FISH, THE BALANCE FROM COTTONSEED MEAL AND SODIUM NITRATE (1-7 OF THE TOTAL NITROGEN IN THE NITRATE).
* These two materials used in amounts which theoretically would
not change the soil reaction.
PLOT N7 ONE HALF NITROGEN FROM FINE TANKAGE, THE BALANCE FROM COTTONSEED MEAL AND SODIUM NITRATE (1-7 THE TOTAL NITROGEN IN THE NITRATE).
From the above figures it is seen that the slight variation in the amounts of ammonia applied to the different plots is negligible. There is, however, a wide difference as to the type of substances used as nitrogen carriers. Plot N1 had one seventh of its nitrogen in mineral form; Plot N2, one half mineral nitrogen; Plot N3, all mineral nitrogen; Plot N4, one half mineral nitrogen; Plot N5,. all mineral nitrogen; Plot N6, and Plot N7, one seventh mineral nitrogen. The amounts of potash and phosphoric acid added to the above plots was the same in all cases, approximately 240 pounds K2O, and 225 pounds P2O, per acre.
SEASON OF 1922
The average yield and quality of the triplicate plots in 1922 as recorded by Chapman is presented in Table I.
TABLE I. EFFECTS OF Different SOURCES OF NITROGEN ON THE YIELD AND QUALITY OF PRIMED HAVANA-1922.
Lbs. ammonia per acre Av. yield cured leaf, lbs. per acre Genera!
A study of the above table shows that plots treated with all mineral nitrogen fertilizer had a tendency to give greater yields but poorer quality tobacco than plots receiving nitrogen of vegetable or animal origin. The quality of the tobacco on Plots N3 and N5, which received all the nitrogen in a mineral form, was so poor as to warrant an appraisal of fifteen cents a pound less than any other tobacco grown in this series. Not only was the tobacco of the first and second primings very poor, but the fourth was also of little character. The colors especially were poor, running almost entirely to a yellowish red, and not clean. Plots N1 and N6 were of the best quality and had a better finish than any of the