LI B 
 
 OF THE 
 
 UN IVLRSITY 
 OF ILLINOIS 
 
 oo.433-444 
 
 clop 
 
.CIRCULATING 
 
 UNBOUND 
 
 NG CORY; 
 
CONTENTS 
 
 PAGE 
 
 METHODS EMPLOYED IN THE EXPERIMENT 275 
 
 Fertilizer Applications 276 
 
 Growing the Plants 278 
 
 Pruning and Training 279 
 
 Pollination 279 
 
 Watering and Ventilation 280 
 
 Harvesting the Crop 280 
 
 YIELDS FROM THE DIFFERENT FERTILIZER 
 
 TREATMENTS 280 
 
 Spring Crop Much Larger Than Fall 281 
 
 No Advantage in Nitrogen or Potassium Supplements 282 
 
 Manure Alone Proved Equal to MsP for Fall Crop 286 
 
 LITERATURE CITED 287 
 
 CONCLUSIONS... . 288 
 
 Urhana, Illinois November, 1937 
 
 Publications in the Bulletin series report the results of investigations made 
 by or sponsored by the Experiment Station 
 
Fertilizer Experiments With 
 Greenhouse Tomatoes 
 
 By J. W. LLOYD, Chief in Olericulture, and B. L. WEAVER, 
 First Assistant in Olericulture 
 
 THE PRODUCTION of hothouse tomatoes is receiving in- 
 creased attention by Illinois growers who are seeking to utilize 
 their greenhouses to better advantage. For the inexperienced 
 grower one of the first problems is the proper fertilizing of the soil. 
 Previous experiments by the Illinois Station in the fertilizing of 
 outdoor tomatoes in southern, 4 * central, 5 * and northern 6 * Illinois and 
 of greenhouse tomatoes grown as a late spring crop on raised benches 3 * 
 have shown the importance of manure and phosphorus in the ferti- 
 lizing of this crop under the conditions studied. Experiments in neigh- 
 boring states also have indicated superior yields from the use of 
 manure and phosphorus in the production of the outdoor crop. 1 - 10 * 
 Results of experiments in England 9 * where tomatoes are grown only 
 under glass, suggested the possibility of different responses of toma- 
 toes to specific fertilizer treatments at different seasons of the year, 
 particularly treatments involving the use of nitrogen and potash. 
 
 In the light of these various experiments it was deemed advisable 
 to run a series of tests in the fertilizing of greenhouse tomatoes grown 
 in ground beds, as both fall and spring crops, particularly to determine 
 the effect of fractional applications of nitrogen and potash at different 
 stages of the plant's development, supplementary to a basic treatment 
 of manure and phosphorus. Records were secured on six fall crops 
 and four spring crops. Upon analyzing the data in reference to the 
 fall crop it seemed advisable to conduct a supplementary test involving 
 twelve replications to obtain further data regarding the relative yields 
 of tomato plants treated with manure alone and with manure and 
 superphosphate in the fall crop. Data on the main experiment and on 
 the supplementary test are included in this report. 
 
 METHODS EMPLOYED IN THE EXPERIMENT 
 
 The tomatoes in the main experiment were grown in a new house, 
 well exposed to light, which had been erected less than a year at the 
 time the experiment was started in the fall of 1930. The dimensions 
 of the house were 104 feet by 29 feet 9 inches inside the concrete walls. 
 The walls were only 2 feet high, with 5 feet of glass from the top of 
 the walls to the eaves of the house. There was a line of ventilators 
 
 275 
 
276 BULLETIN No. 438 [November, 
 
 on each side of the ridge but no side ventilation. Heating coils 
 originally extended along all four walls but were removed from the 
 east end of the house before the close of the experiment on account of 
 excessive heat. Boards were laid for walks next to the pipe coils on all 
 sides of the house, and there was a 12-inch board walk extending 
 lengthwise thru the center of the house, dividing the available planting 
 area into two strips each 12 feet wide and running the length of the 
 house. Before planting each crop, the entire soil area within the walls 
 was spaded and all board walks relaid afterwards. 
 
 The soil in the house was the dark-colored upland prairie soil com- 
 mon in the corn belt. The area had been used for the growing of 
 vegetables for several years before the house was built and was in a 
 fairly good state of fertility as a result of repeated manuring, tho no 
 commercial fertilizer had been applied. 
 
 The house was laid out for planting 40 rows of tomatoes 30 inches 
 apart crossways of the house, with the plants 18 inches apart in the 
 row, each row consisting of 16 plants (8 on each side of the center 
 walk). Thus the number of plants required to plant the house was 640. 
 The first row and the fortieth were considered as buffer rows; the 
 other 38 rows were arranged in pairs, each pair constituting a plot to 
 receive a given fertilizer treatment. The same area was given the same 
 treatment thruout the experiment. One row in each plot was planted 
 to the Urbana Forcing variety and the other to the Lloyd Forcing. 2 * 
 
 The supplementary experiment conducted in the fall of 1936 was 
 in a different house, in which the soil had been uniformly treated with 
 manure for previous crops. 
 
 Fertilizer Applications 
 
 Before planting each crop the soil thruout the house received a 
 heavy, uniform dressing of rotted manure which was well mixed with 
 the soil by spading. 
 
 The manure was not weighed nor measured, but was probably 
 equivalent to at least 30 tons an acre. After spading, the soil was raked 
 smooth and marked out for planting. All applications of fertilizers 
 other than manure were made after planting. 
 
 In the main experiment a basic application of superphosphate 
 equivalent to 1,000 pounds of 16-percent superphosphate an acre was 
 made to practically all the plots, including those designated as check 
 plots. This material was supplemented by nitrate of soda or muriate 
 of potash, or both, applied either early or late, or both early and late, 
 on various plots. The early application of nitrate was equivalent to 
 375 pounds of 15.5-percent nitrate of soda an acre, and the late appli- 
 
1937] 
 
 FERTILIZER EXPERIMENTS WITH GREENHOL-SE TOMATOES 
 
 277 
 
 cation was of the same amount. Each 375 pounds was divided into 
 two 187i/2-pound applications. There was an interval of three weeks 
 between successive applications. The muriate of potash was applied in 
 
 TABLE 1. FERTILIZER TREATMENT OF THE VARIOUS TOMATO PLOTS 
 
 Plot 
 
 Basic treatment 
 
 Supplementary treatment 
 
 Early 
 
 Late 
 
 1 (check) . . 
 
 Manure and superphosphate 
 Manure alone 
 Manure and superphosphate 
 
 Manure and superphosphate 
 Manure and superphosphate 
 Manure and superphosphate 
 
 Manure and superphosphate 
 Manure and superphosphate 
 Manure and superphosphate 
 
 Manure and superphosphate 
 Manure and superphosphate 
 Manure and superphosphate 
 
 Manure and superphosphate 
 Manure and superphosphate 
 Manure and superphosphate 
 
 Manure and superphosphate 
 Manure and superphosphate 
 Manure and superphosphate 
 
 Manure and superphosphate 
 
 None 
 None 
 Nitrate 
 
 None 
 Nitrate 
 Nitrate 
 
 None 
 None 
 None 
 
 None 
 Potash 
 Potash 
 
 None 
 Potash 
 Nitrate and potash 
 
 None 
 None 
 Nitrate and potash 
 
 None 
 
 None 
 None 
 None 
 
 None 
 Nitrate 
 Potash 
 
 None 
 Nitrate 
 Potash 
 
 None 
 Nitrate 
 None 
 
 None 
 Potash 
 None 
 
 None 
 Nitrate and potash 
 Nitrate and potash 
 
 None 
 
 2 
 
 3 
 
 4 (check) 
 
 5 
 
 6. ... 
 
 7 (check) . . . 
 
 8 
 
 9 
 
 10 (check) . . . 
 
 11 
 
 12 
 
 13 (check)... 
 
 14 
 
 15 
 
 16 (check) 
 
 17 
 
 18 
 
 19 (check) 
 
 
 TABLE 2. STAGES OF PLANT DEVELOPMENT WHEN FERTILIZERS WERE APPLIED 
 AT THREE- WEEK INTERVALS 
 
 
 First 
 
 Second application 
 
 Third application 
 
 Fourth application 
 
 Days 
 
 
 applica- 
 
 
 
 
 from last 
 
 Year 
 
 tion, days 
 
 
 
 
 
 
 
 applica- 
 
 
 after 
 setting 
 plants 
 
 Height 
 
 Clusters 
 in bloom 
 
 Height 
 
 Clusters 
 in bloom 
 
 Height 
 
 Clusters 
 in bloom 
 
 tion to 
 ripe 
 fruit 
 
 Fall crop 
 
 1930 
 
 7 
 
 ft. 
 
 2d 
 
 ft. 
 
 4th to 5th 
 
 ft. 
 Top* 
 
 6th to 7th 
 
 -7 
 
 1931 
 
 11 
 
 
 3d 
 
 5-6 
 
 5th 
 
 Top 
 
 7th 
 
 -9 
 
 1932 
 
 12 
 
 3-3>^ 
 
 2d to 3d 
 
 5V6-6 
 
 5th to 6th 
 
 Top 
 
 7th to 8th 
 
 9 
 
 1933 
 
 9 
 
 2H-3 
 
 2d 
 
 *MJ 
 
 4th 
 
 6-7 
 
 6th to 7th 
 
 1 
 
 1934 
 
 10 
 
 
 2d 
 
 6 
 
 5th 
 
 Top 
 
 7th to 9th 
 
 11 
 
 1935 
 
 10 
 
 2-2>^ 
 
 1st 
 
 4^-5 
 
 3d to 4th 
 
 6>$-7 
 
 6th 
 
 14 
 
 
 
 
 
 
 
 
 
 
 Spring crop 
 
 1932 
 
 8 
 7 
 5 
 15 
 
 2 
 
 1st 
 1st 
 1st 
 1st 
 
 4-5 
 3>i-4 
 4-4H 
 
 3d to 4th 
 3d to 4th 
 4th 
 4th 
 
 6^-7 
 5-6 
 
 6 
 
 7th 
 6th 
 6th to 7th 
 6th 
 
 4 
 4 
 
 14 
 
 1933 
 
 1934 
 
 1935 
 
 
 "Top" = top of trellis, 7><j feet from ground. The plants were topped when they reached 
 this height. 
 
278 BULLETIN No. 438 [November, 
 
 like manner in amounts equivalent to 200 pounds of 50-percent potash 
 an acre early and the same amount late. 
 
 Since light conditions were expected to be different on the north 
 and the south sides of the house, the half of each plot on each side 
 of the center walk was treated as a separate unit. The area occupied 
 by the 16 plants in each half-plot was 5 by 12 feet, which is equivalent 
 to 1/726 acre. To insure accuracy, the fertilizer for each half-plot was 
 weighed separately in grams. 
 
 All initial applications of fertilizer were made between five and 
 fifteen days after the plants had been transplanted into the experi- 
 mental house, the time varying somewhat according to the size of the 
 plants when set. The superphosphate was scattered as uniformly as 
 possible over the entire area of each plot except that care was taken 
 to avoid having the material come in direct contact with the plants, 
 and that no material was placed under the narrow boards that served 
 as walks between the plots. The nitrate and potash were each scattered 
 in a circle approximately 10 inches in diameter about each plant. Sub- 
 sequent applications of these two materials were made in a similar 
 manner. Immediately after the fertilizers were applied they were 
 thoroly raked into the soil. 
 
 The fertilizer treatment of the various plots in the main experiment 
 is indicated in Table 1 ; and the stage of development of the plants 
 at the time of each application is indicated in Table 2. 
 
 Growing the Plants 
 
 In producing the plants to be used in these experiments, the seed 
 was sown in flats placed on a greenhouse bench. While still very small, 
 the plants were pricked out into 2^ -inch pots which were plunged in 
 the bench. Except for the 1935-36 fall crop, the plants were shifted 
 to 4-inch pots before being transplanted to the fruiting house. In all 
 the potting a soil composed of 4 parts garden loam, 2 parts rotted 
 manure, and 1 part fine sand was used. Many more plants than needed 
 were started so that a uniform lot could be selected when planting the 
 house. 
 
 In starting the plants for the fall crop an attempt was made to 
 have the plants ready to set in the house as soon as the excessive heat 
 of summer was over and in time for the main crop of blossoms to set 
 their fruit before the dark days of December arrived. The starting 
 of the plants for the spring crop was timed with a view to having 
 them in prime condition for planting within a few days after the 
 harvest of the fall crop was completed. Thus there would be prac- 
 
1937] 
 
 FERTILIZER EXPERIMENTS WITH GREENHOUSE TOMATOES 
 
 279 
 
 tically no loss of use of the house between crops and the harvest of 
 the spring crop would be completed before local outdoor tomatoes 
 became abundant. Dates of planting and harvesting the various crops 
 involved in the experiment are given in Table 3. 
 
 TABLE 3. DATES OF PLANTING AND HARVESTING TOMATOES FROM 
 EXPERIMENTAL PLOTS 
 
 Year 
 
 Date 
 seeded 
 
 Date set 
 in house 
 
 Date of 
 first 
 picking 
 
 Days from 
 seed to 
 harvest 
 
 Date of 
 
 last 
 picking 
 
 Length of 
 harvest in 
 days 
 
 Fall crop 
 
 1930-31 . 
 
 July 22 
 
 Sept. 3 
 
 Nov 5 
 
 106 
 
 Jan. 26 
 
 82 
 
 1931-32 
 
 Aug. 3 
 
 Sept. 21 
 
 Nov 25 
 
 114 
 
 Feb. 1 
 
 68 
 
 1932-33 
 
 July 30 
 
 Sept. 2 
 
 Nov 7 
 
 too 
 
 Jan. 13 
 
 67 
 
 1933-34 
 
 Aug. 1 
 
 Sept. 5 
 
 Nov 17 
 
 108 
 
 Feb. 2 
 
 77 
 
 1934-35 . 
 
 
 Sept. 10 
 
 Nov 11 
 
 97 
 
 Feb 5 
 
 86 
 
 1935-36 
 
 Aug. 17 
 
 Sept. 14 
 
 Dec. 10 
 
 115 
 
 Feb. 8 
 
 60 
 
 
 
 
 
 107 
 
 
 73 
 
 
 
 
 
 
 
 
 Spring crop 
 
 1931-32 
 
 Dec. 19 
 
 Feb. 4 
 
 Apr. 19 
 
 121 
 
 July 5 
 
 77 
 
 1932-33 
 
 Dec. 17 
 
 Jan. 31 
 
 Apr. 15 
 
 123 
 
 June 30 
 
 76 
 
 1933-34 . . 
 
 Dec. 16 
 
 Feb. 5 
 
 Apr. 14 
 
 119 
 
 July 5 
 
 82 
 
 1934-35 
 
 Dec. 23 
 
 Feb. 6 
 
 May 6 
 
 134 
 
 July 19 
 
 74 
 
 
 
 
 
 124 
 
 
 77 
 
 
 
 
 
 
 
 
 Pruning and Training 
 
 The tomato plants were pruned to single stems by repeated re- 
 moval of side shoots as they appeared, and were tied to upright cords 
 fastened to crosswires at the top and to looped wires forced into the 
 ground at the bottom. Tyings at intervals of about one foot were 
 necessary to keep the plants in place. The top of the trellis was 7i/ 
 feet from the ground, and the plants were topped when they reached 
 that height. The number of clusters per plant varied from seven to 
 nine, depending largely upon the length of the internodes, which 
 varied somewhat from season to season and from plant to plant. 
 
 Pollination 
 
 Pollination was effected by merely tapping the clusters of blossoms 
 or the supporting cord with a padded stick. This was done every day, 
 usually in the early afternoon and preferably when the sun was shining 
 brightly. This method of pollinating was effective with the varieties 
 used, since both were heavy pollen producers with the stigmas advan- 
 tageously located in reference to the anthers. 
 
280 BULLETIN No. 438 [November, 
 
 Watering and Ventilation 
 
 Care was taken to give the tomato plants optimum moisture condi- 
 tions. Watering was usually withheld as long as possible after planting 
 in order to reduce damping-off. Care was also taken to prevent the 
 water from coming into direct contact with the plants. The frequency 
 of watering varied with the weather and the stage of development of 
 the crop. The general practice was to water heavily at each watering, 
 and then to withhold water as long as feasible. Watering in dark 
 weather was avoided as much as possible. 
 
 Ventilation was given special attention in order to reduce danger 
 from leaf mold and other foliage diseases. An abundance of heat was 
 kept on, and whenever practicable the vents were left partly open in 
 order to prevent the air from becoming too moist. The aim was to 
 maintain a temperature of 60 to 65 F. at night, 65 to 70 F. on 
 cloudy days, and 75 to 80 F. on clear days. On hot days during the 
 early fall and late spring, however, the temperature frequently was 
 from 90 to 95 F. in the house, and sometimes even higher, in spite 
 of having all heating pipes cut off, all vents wide open, and the roof 
 shaded with whitewash. 
 
 Harvesting the Crop 
 
 The tomatoes were allowed to become red-ripe upon the vines, 
 and were picked from two to three times a week, depending upon 
 the season of the year and the rapidity of ripening. The product of 
 each half -row (8 plants) was picked separately and sorted into market- 
 able fruits and culls, on the basis of size and relative smoothness. All 
 fruits weighing less than li/2 ounces each were classified as culls 
 regardless of how smooth they might be; and all rough or misshapen 
 fruits, no matter how large they might be, were likewise regarded as 
 culls. Each grade from each lot was counted and weighed separately. 
 The harvest usually continued for at least ten or eleven weeks, so 
 that there were normally from twenty to thirty pickings in each crop. 
 
 YIELDS FROM THE DIFFERENT FERTILIZER 
 
 TREATMENTS 
 
 For ease of comparison the yields were calculated in terms of 
 ounces per plant and average number of fruits per plant. Only the 
 fruits of marketable grade were considered when comparing yields. 
 The averages for the six fall crops included in the main experiment are 
 given in Table 4 and for the four spring crops in Table 5. The 
 average weights per marketable fruit are also included in these tables. 
 
1937] FERTILIZER EXPERIMENTS WITH GREENHOUSE TOMATOES 281 
 
 TABLE 4. FALL CROP: YIELDS OF TOMATOES PER PLANT, SIX-YEAR AVERAGE 
 
 Plot 
 
 Supplementary treatment 
 (See Table 1) 
 
 Urbana Forcing 
 
 Lloyd Forcing 
 
 Weight per fruit 
 
 Weight 
 
 Number 
 of fruits 
 
 Weight 
 
 Number 
 of fruits 
 
 Urbana 
 
 Lloyd 
 
 2 
 
 3 
 5 
 6 
 
 8 
 9 
 
 11 
 12 
 14 
 
 15 
 17 
 18 
 
 (Manure alone) 
 
 Of. 
 
 58.5 
 
 60.1 
 61.6 
 63.6 
 
 63.9 
 58.0 
 
 64.4 
 61.2 
 63.9 
 
 63.4 
 64.6 
 59.3 
 
 61.9 
 61.5 
 
 18.6 
 
 19.0 
 20.5 
 20.9 
 
 20.9 
 19.0 
 
 21.2 
 19.5 
 21.2 
 
 20.7 
 22.1 
 20.0 
 
 20.3 
 20.1 
 
 OS. 
 
 73.6 
 
 68.6 
 68.4 
 66.6 
 
 64.8 
 62.1 
 
 69.3 
 67.2 
 69.0 
 
 69.2 
 68.9 
 64.5 
 
 67.7 
 68.2 
 
 25.5 
 
 23.7 
 
 24.3 
 24.2 
 
 23.4 
 22.5 
 
 24.5 
 23.5 
 24.3 
 
 23.9 
 24.6 
 23.6 
 
 24.0 
 24.0 
 
 OS. 
 
 3.14 
 
 3.16 
 3.05 
 3.04 
 
 3.06 
 3.05 
 
 3.04 
 3.14 
 3.01 
 
 3.06 
 2.92 
 2.96 
 
 3.05 
 3.06 
 
 OS. 
 
 2.88 
 
 2.89 
 2.81 
 2.75 
 
 2.77 
 2.76 
 
 2.83 
 2.86 
 2.84 
 
 2.89 
 2.80 
 2.73 
 
 2.72 
 2.84 
 
 N early late . . 
 
 N early. N late 
 
 N early. K late 
 
 early, N late 
 
 early, K late 
 
 K early, N late 
 
 K early, late 
 
 K early, K late 
 
 NK early, late 
 
 early NK late 
 
 NK early NK late 
 
 Average of treated plots 
 
 Average of checks (MsP) .... 
 
 TABLE 5. SPRING CROP: YIELDS OF TOMATOES PER PLANT, FOUR- YEAR AVERAGE 
 
 Plot 
 
 Supplementary treatment 
 (See Table 1) 
 
 Urbana Forcing 
 
 Lloyd Forcing 
 
 Weight per fruit 
 
 Weight 
 
 Number 
 of fruits 
 
 Weight 
 
 Number 
 of fruits 
 
 Urbana 
 
 Lloyd 
 
 2 
 
 3 
 5 
 6 
 
 8 
 9 
 
 11 
 12 
 14 
 
 15 
 17 
 18 
 
 (Manure alone) 
 
 OS. 
 
 153.6 
 
 153.6 
 142.6 
 143.7 
 
 151.1 
 138.3 
 
 150.0 
 155.4 
 156.3 
 
 162.5 
 148.4 
 151.2 
 
 146.3 
 151.9 
 
 36.5 
 
 37.8 
 35.8 
 34.7 
 
 37.5 
 34.6 
 
 37.6 
 37.7 
 37.3 
 
 37.3 
 37.6 
 37.7 
 
 36.8 
 36.4 
 
 OS. 
 
 163.8 
 
 166.6 
 167.5 
 156.6 
 
 153.5 
 160.7 
 
 175.0 
 170.1 
 168.3 
 
 170.5 
 166.2 
 157.6 
 
 164.7 
 166.5 
 
 45.0 
 
 43.7 
 44.6 
 44.0 
 
 44.1 
 45.3 
 
 46.7 
 46.1 
 46.7 
 
 47.0 
 45.1 
 45.0 
 
 45.6 
 45.8 
 
 ot. 
 4.21 
 
 4.06 
 3.98 
 4.14 
 
 4.00 
 4.00 
 
 3.98 
 4.12 
 4.19 
 
 4.35 
 3.94 
 4.01 
 
 4.08 
 
 4.17 
 
 OS. 
 
 3.64 
 
 3.81 
 3.75 
 3.55 
 
 3.48 
 3.54 
 
 3.74 
 3.68 
 3.60 
 
 3.60 
 3.68 
 3.50 
 
 3.62 
 3.63 
 
 N early, late 
 
 N early, N late 
 
 N early. K late 
 
 early, N late 
 
 early, K late 
 
 K early, N late 
 
 K early, late 
 
 K early, K late 
 
 NK early, late 
 
 early, NK late 
 
 NK early NK late 
 
 Average of treated plots 
 Average of checks (MsP) .... 
 
 Spring Crop Much Larger Than Fall 
 
 There were striking differences in yield between the fall and the 
 spring crops. In the spring the average number of fruits per plant was 
 80 percent greater for Urbana Forcing and 90 percent greater for 
 Lloyd Forcing than in the fall. The average size of fruit in both 
 
282 
 
 BULLETIN No. 438 
 
 [November, 
 
 varieties was approximately one-third larger in the spring than in the 
 fall. With both number and size of fruits greater in the spring the 
 yields in weight were necessarily much larger in spring, averaging 
 nearly 2i/2 times the fall yields. Furthermore there was less variation 
 in yield from year to year in the spring crop than in the fall crop. 
 
 The average yields from all check plots, including both varieties, 
 for each year show that the yields in the fall varied from 49 to 94 
 ounces per plant (Table 6). This indicates that the yields in the fall 
 one year may be nearly double those of another year under the same 
 
 TABLE 6. AVERAGE YIELDS PER PLANT FROM ALL CHECK PLOTS 
 OF BOTH VARIETIES EACH SEASON 
 
 Year 
 
 Fall crop 
 
 Spring crop 
 
 1930-31 
 
 oz. 
 68 
 
 oz. 
 
 1931-32 
 
 49 
 
 163 
 
 1932-33 
 
 59 
 
 143 
 
 1933-34 
 
 61 
 
 169 
 
 1934-35 
 
 94 
 
 161 
 
 1935-36 . 
 
 55 
 
 
 Average 
 
 64 
 
 159 
 
 
 
 
 fertilizer treatment. Such variations in yield are attributable largely 
 to variations in weather conditions, particularly intensity and amount 
 of sunlight during the setting and development of the fruit. On the 
 other hand, the average yields from the spring check plots varied only 
 from 143 to 169 ounces per plant, a difference of only 18 percent 
 between the lowest crop and highest crop during the four seasons. 
 
 Incidentally these results indicate a justification for the common 
 practice among commercial growers of growing only the spring crop. 
 
 No Advantage in Nitrogen or Potassium Supplements 
 
 Data presented in Tables 4 and 5 indicate that there was little differ- 
 ence between the average yields from all treated plots and from all 
 check plots during the period of the experiment. Each year some of 
 the treated plots showed slight increases in yield (from 3.6 to 13.4 
 percent) over the average of the checks for that season, but the same 
 plot did not appear as the high-yielding plot with sufficient frequency to 
 make the results significant. 
 
 A better basis for determining the effectiveness of the different 
 fertilizer treatments is a statistical analysis of the yield from each 
 treated plot each season compared with its adjacent check. The sum- 
 mary of such an analysis of the yields in ounces per plant is presented 
 
1937] 
 
 FERTILIZER EXPERIMENTS WITH GREENHOUSE TOMATOES 
 
 283 
 
 TABLE 7. FALL CROP, URBANA FORCING: YIELD OF MARKETABLE TOMATOES, 
 
 Six- YEAR AVERAGE 
 
 Plot 
 
 
 Ounces per 
 
 Increase over 
 
 Odds 
 
 M.D. 
 
 
 
 plant 
 
 adjacent check 
 
 
 P.E. 
 
 1 
 
 (Manure alone) 
 
 58.5 
 
 8.58 2.05 
 
 93:1 
 
 4 2 
 
 3 
 
 N early late 
 
 60 1 
 
 4.83 1.32 
 
 51:1 
 
 3 7 
 
 5 
 
 N early, N late 
 
 61.6 
 
 -3.25 1 .51 
 
 9:1 
 
 2 2 
 
 6 
 
 N early, K late 
 
 63.6 
 
 -1.75 1.70 
 
 3:1 
 
 1.0 
 
 g 
 
 early N late 
 
 63 9 
 
 1 42 2 00 
 
 2-1 
 
 7 
 
 9 
 
 early, K late 
 
 58.0 
 
 2.17 2.09 
 
 3:1 
 
 1 
 
 11 
 
 K early, N late . . . 
 
 64.4 
 
 4.25 2.09 
 
 8- 
 
 2 
 
 12 
 
 K early, late 
 
 61.2 
 
 3.92 1.41 
 
 18: 
 
 2 8 
 
 14 
 
 K early K late 
 
 63 9 
 
 1 17 1 47 
 
 2- 
 
 g 
 
 15 
 
 N K early, late 
 
 63.4 
 
 1.33 1.56 
 
 2: 
 
 .9 
 
 17 
 
 Dearly, NK late . . 
 
 64 6 
 
 2.50 1 .64 
 
 5: 
 
 1 5 
 
 18 
 
 NK early, NK late 
 
 59.3 
 
 4.08 1.43 
 
 21: 
 
 2.9 
 
 
 Average of treated plots . 
 
 61.9 
 
 
 
 
 
 Average of checks (MsP). 
 
 61.5 
 
 
 
 
 
 
 
 
 
 
 TABLE 8. FALL CROP, LLOYD FORCING: YIELD OF MARKETABLE TOMATOES, 
 
 SIX-YEAR AVERAGE 
 
 
 
 Ounces per 
 
 Increase over 
 
 
 M.D. 
 
 
 
 plant 
 
 adjacent check 
 
 
 P.E. 
 
 2 
 
 (Manure alone) 
 
 73.6 
 
 12.58 2.59 
 
 198:1 
 
 4.9 
 
 3 
 
 N early, late 
 
 68.6 
 
 1.42 .53 
 
 3:1 
 
 .9 
 
 5 
 
 N early, N late 
 
 68.4 
 
 1.67 .76 
 
 3:1 
 
 1.0 
 
 6 
 
 N early, K late 
 
 66.6 
 
 -4.00 .50 
 
 17:1 
 
 2.7 
 
 8 
 
 early, N late 
 
 64.8 
 
 -5.75 .93 
 
 24: 
 
 3.0 
 
 9 
 
 early, K late . 
 
 62.1 
 
 10.58 .64 
 
 1110: 
 
 6.5 
 
 11 
 
 K early N late 
 
 69.3 
 
 -3.33 .45 
 
 11: 
 
 2.3 
 
 12 
 
 K early, late 
 
 67.2 
 
 .75 .53 
 
 2: 
 
 .5 
 
 14 
 
 K early, K late 
 
 69.0 
 
 1.08 .29 
 
 2: 
 
 .8 
 
 15 
 
 N K early. late 
 
 69.2 
 
 2.08 .42 
 
 4: 
 
 1.5 
 
 17 
 
 early, NKlate 
 
 68.9 
 
 1.83 .11 
 
 5: 
 
 1.7 
 
 18 
 
 N K early, NK late 
 
 64.5 
 
 3.67 1.16 
 
 30:1 
 
 3.2 
 
 
 Average of treated plots. . 
 
 67.7 
 
 
 
 
 
 Average of checks (MsP). 
 
 68.2 
 
 
 
 
 
 
 
 
 
 
 in Tables 7, 8, 9, and 10. a Each variety has been considered separately 
 for the fall and the spring crop. Since the yield records were kept 
 separately for the given treatment on each side of the greenhouse, 
 twelve yield records for each treatment in the main experiment are 
 available for the fall crop and eight records for the spring crop. This 
 
 'An analysis was also made on the basis of number of fruits per plant, 
 but since the results were not essentially different, only the data covering the 
 one analysis are presented here. 
 
284 
 
 BULLETIN No. 438 
 
 [November, 
 
 TABLE 9. SPRING CROP, URBANA FORCING: YIELD OF MARKETABLE TOMATOES, 
 
 FOUR- YEAR AVERAGE 
 
 
 
 Ounces per 
 
 Increase over 
 
 rviH 
 
 M.D. 
 
 
 
 plant 
 
 adjacent check 
 
 
 P.E. 
 
 2 
 
 (Manure alone) 
 
 153.6 
 
 .87 1.65 
 
 2:1 
 
 .5 
 
 3 
 
 N early, late 
 
 153.6 
 
 2.00 2.70 
 
 2:1 
 
 .7 
 
 5 
 
 N early. N late 
 
 142.6 
 
 -9.00 2.57 
 
 30:1 
 
 3.5 
 
 6 
 
 N early. K late 
 
 143.7 
 
 -1.09 3.75 
 
 <1:1 
 
 .3 
 
 8 
 
 early, N late 
 
 151.1 
 
 5.05 3.88 
 
 4:1 
 
 1.3 
 
 9 
 
 early, K late 
 
 138.3 
 
 -16.12 1.71 
 
 3332:1 
 
 9.4 
 
 11 
 
 K early, N late 
 
 150.0 
 
 -4.05 1.79 
 
 9:1 
 
 2.3 
 
 12 
 
 K early late 
 
 155.4 
 
 -1.05 1.98 
 
 2:1 
 
 .5 
 
 14 
 
 K early, K late 
 
 156.3 
 
 - .75 2.68 
 
 <1:1 
 
 .3 
 
 15 
 
 NK early, late 
 
 162.5 
 
 4.37 3.69 
 
 3:1 
 
 1.2 
 
 17 
 18 
 
 Dearly, NKlate 
 N K early, NK late 
 
 148.4 
 151.2 
 
 146 3 
 
 -9.50 3.97 
 -6.62 3.90 
 
 11:1 
 5:1 
 
 2.4 
 1.7 
 
 
 
 151.9 
 
 
 
 
 
 
 
 
 
 
 is a sufficient number of items to render the results of the statistical 
 study reliable. 
 
 The significance of the differences in yield were determined by two 
 methods, viz.: (1) Student's "odds" 11 - 12 * and (2) mean difference 
 divided by probable error. Odds of less than 30 to 1 indicate that there 
 was no significant difference in the yields of the two plots under com- 
 parison, while odds greater than 30 to 1 indicate that the difference 
 was significant. 7 ' 8 * On the other basis of comparison, where the mean 
 
 TABLE 10. SPRING CROP, LLOYD FORCING: YIELD OF MARKETABLE TOMATOES, 
 
 FOUR- YEAR AVERAGE 
 
 Plot 
 
 Supplementary treatment 
 
 Ounces per 
 plant 
 
 Increase over 
 adjacent check 
 
 Odds 
 
 M.D. 
 P.E. 
 
 2 
 
 (Manure alone) 
 
 163.8 
 
 7.38 3.32 
 
 9:1 
 
 2.2 
 
 3 
 
 Nearly, late 
 
 166.6 
 
 9.87 3.64 
 
 14:1 
 
 2.7 
 
 5 
 
 N early, N late 
 
 167.5 
 
 5.25 3.73 
 
 4:1 
 
 1.4 
 
 6 
 
 N early. K late 
 
 156.6 
 
 -9.25 2.00 
 
 88:1 
 
 4.6 
 
 8 
 
 early, N late 
 
 153.5 
 
 10.88 2.23 
 
 108:1 
 
 4.9 
 
 9 
 
 early, K late . 
 
 160 7 
 
 10 62 2 93 
 
 34-1 
 
 3.6 
 
 11 
 
 K early, N late . 
 
 175 
 
 3 62 2 76 
 
 4-1 
 
 1.3 
 
 12 
 
 K early. late 
 
 170.1 
 
 2.87 2 99 
 
 3:1 
 
 1.0 
 
 14 
 
 K early, K late 
 
 168.3 
 
 1.13 1.43 
 
 2:1 
 
 .8 
 
 15 
 
 N K early. late. . 
 
 170.5 
 
 -4.75 2.98 
 
 5:1 
 
 1.6 
 
 17 
 
 early. NKlate 
 
 166 2 
 
 9 50 3 91 
 
 11:1 
 
 2.4 
 
 18 
 
 NK early, NKlate 
 
 157.6 
 
 -7.00 2.63 
 
 14:1 
 
 2.7 
 
 
 Average of treated plots.. 
 
 164.7 
 
 
 
 
 
 Average of checks (MsP). 
 
 166.5 
 
 
 
 
 
 
 
 
 
 
1937] 
 
 FERTILIZER EXPERIMENTS WITH GREENHOUSE TOMATOES 
 
 285 
 
 difference is divided by the probable error, a quotient of less than 3.2 
 indicates that there was no significant difference between the yields 
 under comparison. 
 
 In the fall crop apparently the only significant increase in yield 
 as compared with that of the adjacent check plot was on the plot 
 treated with manure alone. The increase appeared to be significant 
 in both varieties and by both methods of calculation. However, the 
 check plot with which the manure-treated plot was compared was at 
 the extreme east end of the house, with only a single buffer row of 
 plants between it and the wall. The yield from this check plot was 
 unduly depressed, so that the difference in yield was due partly to the 
 low yield of this particular check. These results led to the supple- 
 mentary test reported on pages 286-7. 
 
 The only other significant differences in the fall crop in the main 
 experiment were decreases rather than increases in yield compared 
 with the adjacent checks. Plot 3, treated with nitrate of soda early in 
 the season, showed a significant decrease in yield of Urbana Forcing; 
 and altho there was some decrease in yield of Lloyd Forcing the 
 difference was not significant. Plot 9, treated with potash late in the 
 season, showed a significant decrease in yield of Lloyd Forcing, but not 
 of Urbana Forcing. When the two varieties were combined (Table 
 11), the decrease in yield for Plot 9 was significant. Plot 18, treated 
 with both nitrogen and potash early and late, showed a significant 
 decrease in yield for the two varieties combined and for Lloyd Forcing, 
 
 TABLE 11. FALL CROP, BOTH VARIETIES COMBINED: 
 
 TOMATOES 
 
 YIELD OF MARKETABLE 
 
 Plot 
 
 Supplementary treatment 
 
 Ounces per 
 plant 
 
 Increase over 
 adjacent check 
 
 Odds 
 
 M.D. 
 P.E. 
 
 2 
 
 (Manure alone) 
 
 66.0 
 
 10.58 1.67 
 
 5998:1 
 
 6.4 
 
 3 
 
 Nearly, late 
 
 64.3 
 
 -3.12 .04 
 
 32:1 
 
 3.0 
 
 5 
 
 N early, N late 
 
 65.0 
 
 -2.46 .17 
 
 10:1 
 
 2.1 
 
 6 
 
 N early, K late 
 
 65.1 
 
 2.88 .14 
 
 16:1 
 
 2.5 
 
 8 
 
 early, N late 
 
 64.3 
 
 3.58 .42 
 
 16:1 
 
 2.5 
 
 9 
 
 early, K late . 
 
 60 
 
 6.38 .45 
 
 251:1 
 
 4.4 
 
 11 
 
 K early, N late 
 
 66.8 
 
 .46 .37 
 
 <1:1 
 
 .3 
 
 12 
 
 K early, late 
 
 64.2 
 
 -2.34 .05 
 
 12:1 
 
 2.2 
 
 14 
 
 K early. Klate 
 
 66.4 
 
 .04 .99 
 
 <1:1 
 
 .0 
 
 IS 
 
 NK early, late 
 
 66.3 
 
 1.70 1.06 
 
 6:1 
 
 1.6 
 
 17 
 18 
 
 early, NKlate 
 N K early, N Klate 
 
 66.7 
 61.9 
 
 2.16 .98 
 -3.88 .92 
 
 11:1 
 192:1 
 
 2.2 
 
 4.2 
 
 
 Average of treated plots.. 
 
 64.7 
 
 
 
 
 
 Average of checks (MsP). 
 
 64 8 
 
 
 
 
 
 
 
 
 
 
286 
 
 BULLETIN No. 438 
 
 [November, 
 
 TABLE 12. SPRING CROP, BOTH VARIETIES COMBINED: YIELD OF MARKETABLE 
 
 TOMATOES 
 
 Plot 
 
 Supplementary treatment 
 
 Ounces per 
 plant 
 
 Increase over 
 adjacent check 
 
 Odds 
 
 M.D. 
 P.E. 
 
 2 
 
 (Manure alone) 
 
 158.7 
 
 4.12 2.19 
 
 7:1 
 
 1.9 
 
 3 
 
 N early, late 
 
 160.1 
 
 5.93 2.36 
 
 15:1 
 
 2.5 
 
 5 
 
 N early, N late 
 
 155.1 
 
 1.87 2.56 
 
 2:1 
 
 .7 
 
 6 
 
 N early, K late 
 
 150.1 
 
 -5.17 2.23 
 
 12:1 
 
 2.3 
 
 8 
 
 early, N late 
 
 152.3 
 
 2.91 2.62 
 
 3:1 
 
 1.1 
 
 9 
 
 early, K late 
 
 149.5 
 
 13.37 1.76 
 
 8100:1 
 
 7.6 
 
 11 
 
 K early, N late 
 
 162.5 
 
 .22 1.77 
 
 <1:1 
 
 .1 
 
 12 
 
 K early, late 
 
 162.7 
 
 .91 1.82 
 
 2:1 
 
 .5 
 
 14 
 
 K early K late 
 
 162.3 
 
 .19 1.77 
 
 <1:1 
 
 .1 
 
 15 
 
 NK early Olate . ... 
 
 166.5 
 
 .19 2.50 
 
 <1:1 
 
 .1 
 
 17 
 
 Dearly, NK late 
 
 157.3 
 
 9.50 2.79 
 
 47:1 
 
 3.4 
 
 18 
 
 NK early, NK late 
 
 154.4 
 
 - .19 2.62 
 
 <1:1 
 
 .1 
 
 
 Average of treated plots.. 
 
 155.5 
 
 
 
 
 
 Average of checks (MsP). 
 
 159.2 
 
 
 
 
 
 
 
 
 
 
 but not for Urbana Forcing. When the records of the two varieties 
 were combined 24 items entered into the calculations, instead of the 12 
 items when the two varieties were considered separately. 
 
 Eight treatments showed decreases in yield of each variety as com- 
 pared with the adjacent checks, but only in the plots mentioned above 
 were the differences significant. 
 
 In the spring crop the only significant results were negative; that 
 is, the differences in yield were significant only in those plots where 
 the yields were less than in the adjacent checks. Plot 9 in each variety 
 showed significantly decreased yields, evidently due to the potassium 
 applied late. Lloyd Forcing in Plot 6, treated with nitrogen early and 
 potassium late, and in Plot 8, treated with nitrogen late, also showed 
 significant decreases in yield. Urbana Forcing in Plot 5, treated with 
 nitrogen both early and late, also showed a significant decrease in 
 yield. When both varieties were combined (Table 12), the only signif- 
 icant differences in yield in the spring crop were in Plots 9 and 17. 
 The fertilizer treatments of both of these plots involved the application 
 of potash late in the season. 
 
 Manure Alone Proved Equal to MsP for Fall Crop 
 
 In order to obtain additional data on the effect of manure alone 
 on tomato yields, a supplementary test was made in the fall of 1936. 
 Twenty-four rows each of Urbana Forcing and Lloyd Forcing were 
 included in this test. Alternate plots of two rows each were treated 
 
1937] 
 
 FERTILIZER EXPERIMENTS WITH GREENHOUSE TOMATOES 
 
 287 
 
 TABLE 13. MANURE ALONE COMPARED WITH MANURE AND SUPERPHOSPHATE IN 
 PRODUCING MARKETABLE TOMATOES: FALL CROP, 1936 
 
 
 Urbana 
 Forcing 
 
 Lloyd 
 Forcing 
 
 Both 
 varieties 
 combined 
 
 
 60 84 
 
 75 82 
 
 68 33 
 
 
 56.37 
 
 73.26 
 
 64.81 
 
 
 4.47 
 
 2.56 
 
 3.52 
 
 Probable error 
 
 1.59 
 
 2.08 
 
 1.32 
 
 Mean difference divided by probable error 
 
 2.8 
 
 1.2 
 
 2.7 
 
 Odds 
 
 19:1 
 
 3:1 
 
 2:1 
 
 
 
 
 
 with manure alone, and with manure and superphosphate. In analyz- 
 ing the results, the yield of each row was paired with that of the near- 
 est row receiving the other treatment. The differences in the yields 
 from the two treatments proved not to be significant (Table 13). In 
 the light of these results the more limited data from the spring tests, 
 showing no significant yield differences between the manure and 
 manure-phosphate plots, are worthy of note. 
 
 (For Conclusions see next page.) 
 
 LITERATURE CITED 
 
 1. BROWN, H. D. Growing tomatoes for the canning factory. Purdue Agr. 
 
 Exp. Sta. Bui. 288. 1924. 
 
 2. HUELSEN, W. A. New wilt-resistant tomato varieties for field and green- 
 
 house. 111. Agr. Exp. Sta. Circ. 448. 1936. 
 
 3. LLOYD, J. W. Fertilizer experiments with greenhouse lettuce and tomatoes. 
 
 111. Agr. Exp. Sta. Bui. 286. 1927. 
 
 - Fertilizer experiments with truck crops in southern Illinois. 
 
 111. Agr. Exp. Sta. Bui. 319. 1929. 
 
 Fertilizing tomatoes, sweet corn, and muskmelons in a three- 
 
 4. 
 
 5. 
 
 year rotation. 111. Agr. Exp. Sta. Bui. 364. 1931. 
 
 6. - - and LEWIS, E. P. Fertilizer experiments with ten market- 
 
 garden crops in Cook county, Illinois. 111. Agr. Exp. Sta. Bui. 377. 1932. 
 
 7. LOVE, H. H. A modification of Student's table for use in interpreting 
 
 experimental results. Jour. Amer. Soc. Agron. 16, 68-73. 1924. 
 
 8. - and BRUNSON, A. M. Student's method for interpreting paired 
 
 experiments. Jour. Amer. Soc. Agron. 16, 60-68. 1924. 
 
 9. NURSERY AND MARKET GARDEN INDUSTRIES' DEVELOPMENT SOCIETY, Ltd. Ann. 
 
 Rpt. 7, Exp. and Res. Sta., Turners' Hill, Hertfordshire, England. 1921. 
 
 10. ROSA, J. T., JR. Profitable tomato fertilizers. Missouri Agr. Exp. Sta. Bui. 
 
 169. 1920. 
 
 11. STUDENT. Biometrika 6, 1-25. 1908. 
 
 12. - Biometrika 11, 414-417. 1917. 
 
NITROGEN OR POTASH, or both, used as 
 top dressings to supplement a liberal basic 
 treatment of manure and phosphorus, cannot 
 be depended upon to increase the yield of 
 greenhouse tomatoes grown in ground beds of 
 dark-colored Illinois upland prairie soil. In 
 fact, such treatments may be more detrimental 
 than beneficial. 
 
 Where ample supplies of manure are avail- 
 able, the fall crop of greenhouse tomatoes, and 
 probably the spring crop also, may advanta- 
 geously be grown on ground beds of the kind 
 of soil used in these experiments without any 
 kind of commercial fertilizer supplement. 
 
 The small fall crops of tomatoes obtained in 
 these experiments indicate that commercial 
 growers are justified in their common practice 
 of producing only the spring crop. 
 
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