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McCoLLUM UNIVERSITY OF ILLINOIS AGRICULTURAL EXPERIMENT STATION Bulletin 464 CONTENTS PAGE PLAN OF EXPERIMENT 220 Cropping Scheme 220 Kinds and Amounts of Fertilizer Applied 221 Planting and Handling the Crops 221 EFFECTS OF FERTILIZER ON CUCUMBERS ' 223 Effect on Yields 223 Effect on Earliness 226 Effect on Grade 228 EFFECT OF FERTILIZER ON ONION SETS 228 RESULTS WITH SWEET CORN 230 RESULTS WITH CABBAGE 231 YIELDS AND FERTILIZER COST 233 High Cost of Nitrogen 233 Phosphorus an Important Element 234 Moderate Applications of Potash Sufficient 235 High Cost of Manure Treatment 235 SUMMARY 235 SUGGESTED TREATMENTS.. . 236 Urbana, Illinois March, 1940 Publications in the Bulletin series report the results of investigations made or sponsored by the Experiment Station Fertilizing Onion Sets, Sweet Corn, Cabbage, and Cucumbers in a Four -Year Rotation J. W. LLOYD, Chief in Horticulture, and J. P. McCoLLUM, Assistant Chief in Olericulture "TF OCAL PRODUCTION of vegetables near large consuming centers continues to be an important factor in supplying the vegetable ^ x * needs of Illinois cities. This has remained true notwithstanding the enormous development of vegetable production in favored localities at varying distances from Illinois markets and great improvement in transportation facilities for perishable products. In the vicinity of Chicago, which contains over half the population of the state and which receives vegetable supplies from all domestic producing areas and several foreign countries, local production of vegetables is still an important industry, approximately 1,800 of the 3,200 farms within the borders of Cook county producing vegetables for market. The substitution of motor vehicles for horses in the cities has pro- foundly affected the vegetable industry by greatly reducing the available supply of fresh animal manure. This situation has necessitated a search for other means of maintaining soil fertility in the vegetable-growing areas. Furthermore it is now generally known that stable manure is not a well-balanced fertilizer, and if used in sufficient quantities to furnish enough phosphorus for most vegetable crops, will supply an excess of nitrogen and potash, and cause the gardener to incur needless expense. In any program -of soil maintenance or improvement a definite rotation of crops is usually deemed advisable. Four of the most im- portant vegetable crops grown in the Chicago area are onion sets, 1 sweet corn for market, cabbage, and pickle cucumbers. Therefore, for an experiment in northeastern Illinois planned with a view to develop- ing a workable method of fertilizing vegetable crops without the use of large quantities of manure, these four crops were selected and arranged in a four-year rotation in such a way as to permit the grow- ing of at least three green-manuring crops, in addition to the four cash crops, in each four-year period. 'It has been estimated that Cook county, Illinois, produces at least 80 per- cent of the onion-set crop of the United States. 219 220 BULLETIN No. 464 [March, PLAN OF EXPERIMENT The experiment was carried on at the Cook County Branch Experi- ment Station from 1925 to 1936 inclusive, on soil consisting principally of Lisbon clay loam and silty clay loam, Saybrook silt loam, and Elliott clay loam. These soils are common in the market garden region in the northern part of Cook county and adjacent territory. Cropping Scheme Each plot consisted of %o acre from which the yield records were taken. Alleys 8 feet wide were left between plots. Plants in the alleys were cut out before the beginning of the harvest period or harvested in advance of the harvest for record. In the main series of plots (Series I) the following plan of crop- ping for the four main crops and the cover crops was carried out: Onion seed for the production of sets was sown early in the spring. The sets were harvested in August, and the land was then seeded to a mixture of rye and vetch as a cover crop which was plowed under for green manure before corn-planting time the next spring. Sweet corn was planted for an early market crop. Either at the time of the last cultivation or immediately after the green corn was harvested, the land was seeded to sweet clover. The sweet clover was plowed down for green manure before time for planting late cabbage the next season. Cabbage was transplanted to the field in June. The original plan was to seed rye after harvesting the cabbage, but in practice it was found that the cabbage matured too late to permit the starting of a cover crop, even of rye, the same fall. Therefore, no cover crop followed the cabbage. Pickle cucumbers were planted in late May or early June, after fall plowing. As soon as the harvest was completed, usually by Sep- tember 10, a cover crop of oats was sown. This cover crop was plowed under late in the fall, preparatory to the seeding of onions early the next spring, to start the next cycle of the rotation. Thus, four cash crops and three cover or green-manuring crops were grown on the same land in four years. In addition to the foregoing series of plots with cover crops, an- other small series (Series II) was planted without any cover crops, so that a comparison might be made between manure and a complete commercial fertilizer for maintaining the productivity of the soil. The various plots were replicated so that all four vegetable crops were grown every year, thus making yield records available on each 1940} FERTILIZING FOUR VEGETABLE CROPS IN ROTATION 221 crop for each of the twelve years representing the three full rota- tions, except in years of crop failure or other eventualities. Each year the various treatments for each crop were duplicated. Kinds and Amounts of Fertilizer Applied In Series I cover crops were used without manure on all plots, including the check plots, for maintaining the supply of organic matter in the soil. Different fertilizer mixtures were added to the various plots in order to test their effectiveness in producing satisfactory yields of the respective crops. Each treated plot was adjacent to an untreated check plot. All plots treated with commercial fertilizers were given an annual application at the rate of 1,000 pounds to the acre, the material being scattered broadcast over the surface of the ground and thoroly mixed with the top soil by disking and harrowing during the prepara- tion of the seedbed. The fertilized area of each plot extended to the centers of the adjacent alleys. In making up the different fertilizer mixtures, the three elements nitrogen, phosphorus, and potassium were used in varying propor- tions, representing from to 6 percent nitrogen, from to 12 percent phosphorus, and from to 6 percent potassium. In each mixture con- taining nitrogen, half the nitrogen was derived from nitrate of soda and half from ammonium sulfate. Superphosphate was used as the source of phosphorus and muriate of potash as the source of potas- sium. In Series II the applications of commercial fertilizer were made in the same amounts and in the same manner as in Series I ; the ma- nure was applied broadcast at the rate of 20 tons to the acre just before plowing. In this series all plowing was done in the fall. Applications of 1,000 pounds of commercial fertilizer or 20 tons of manure to the acre wData based on 9 years' yield records. 2 Data based on 8 years' yield records. was a definite increase in the weight of the crop, each increment in nitrogen resulting in a greater yield. The highest concentration of nitrogen (6 percent) resulted in no more heads than the 4-percent formula, but the heads were larger. Use of the fertilizer containing 6 percent of nitrogen increased the yield 68.1 percent over the adjacent checks, an increase equivalent to 6,088 pounds an acre. The need of liberal amounts of phosphorus for the production of cabbage is clearly shown by the response of this crop to increasing amounts of this element. The greatest increase in yield over the ad- jacent check was from the treatment containing the most phosphorus, each increase in the amount of phosphorus being associated with a definite increase in the weight of the crop. In number of heads, also, there was a progressive increase as the amount of phosphorus was increased. The treatment containing the most phosphorus resulted in an in- crease over the adjacent check of 6,776 pounds (more than 3 tons) an acre, or 78.17 percent. Varying the amounts of potassium in the fertilizer caused much less variation in yield than when the quantity of nitrogen or phos- phorus was varied, nearly as good yields being obtained when there was no potassium in the fertilizer as when there was the largest amount. FERTILIZING FOUR VEGETABLE CROPS ix ROTATION 233 Series II. Both treatments in Series II 20 tons of manure and 1,000 pounds of a complete commercial fertilizer (4-8-4) produced significant increases in yield over the adjacent untreated checks. This was true whether yields were measured in number of heads or in weight of trimmed cabbage. Owing to crop failures some years, data on this series are available for only eight years. As an average for the eight years, the yields were somewhat higher from the commercial- fertilizer treatment than from the manure treatment. YIELDS AND FERTILIZER COST From the market gardener's standpoint, the increases in yield ob- tained by using a given fertilizer must of course be considered in rela- tion to the cost of the fertilizer. Tables 8 and 9 throw light on this aspect of the experiments. The yields are given in terms of market units per acre. TABLE 8. COST OF FERTILIZER MATERIALS PER ACRE AND INCREASE IN YIELD OVER ADJACENT CHECK Treatment Increase in yield Material Cost per acre* Cucumbers Onion sets Sweet corn Cabbage Series I (1) 0-8-4 $ 7 37 60-lb. bags 79 4O4b. bu. 60 6 doz. ears 89 2 act. 33 4 (2) 4-8-4 12 59 81.1 67.5 100.6 48 8 (3) 6-8-4 15.21 92.1 73.5 106.2 60.9 (4) 4-0-4 . 7 27 7 7 42 5 66 3 11 9 (5) \.\.\ 9 93 43 7 62 9 130 9 39 9 (6) 4-12-4 15 25 75 9 59 6 114.2 67 8 (7) 4-8-0... 10 54 71.5 27 5 78.2 46 7 (8) 4-8-6 13 61 82.4 54.9 88.6 53.1 Series II (1) 4-8-4 12 59 71 5 65 2 147 2 62 (2) Manure 30 00 82 5 46 3 106 9 56 5 Based upon prices of the materials entering into these fertilizers, delivered at Des Plaines, Illinois, in the spring of 1939: nitrate of soda, $41 per ton; ammonium sulfate, $34.93; superphosphate (20-percent) $21.40; muriate of potash, $41.32. High Cost of Nitrogen It is true that as the amount of nitrogen in the fertilizer applied to the plots in Series I was increased from to 4 to 6 percent, the 234 BULLETIN No. 464 \March, yields of all four crops increased in relation to the check plot. But, with one exception, the cost of the fertilizer per unit of crop increase also advanced. The exception was in the cabbage crop, the cost of the 6-8-4 treatment per unit of crop increase being slightly lower than that of the 4-8-4 treatment. Under the conditions of this experiment and at the prices for ferti- lizer indicated, it would probably not pay to use nitrogen in the ferti- lizer formula for cucumbers or sweet corn. TABLE 9. COST OF FERTILIZER PER UNIT OF INCREASE IN YIELD Treatment Cucumbers Onion sets Sweet corn Cabbage Series I (1) 0-8-4 60-lb. bags 3.093 40-lb. bu. $ 122 dnz. ears J5.083 cwt. $.221 (2) 4-8-4 .155 .186 .125 .258 (3) 6-8-4 165 207 143 .250 (4) 4.0-4 . . . . (i) 171 110 .611 (5) 4.4.4 .227 158 .076 .249 (6) 4-12-4 .201 .256 .134 .225 (7) 4-8-0 . . .147 .383 .135 .226 (8) 4-8-6 . 165 248 154 .256 Series II (1) 4-8-4 . . 176 193 086 .203 (2) Manure .364 648 .281 .531 'The cucumber yield from the 4-0-4 treatment was less than the yield from the check plot. Phosphorus an Important Element Phosphorus proved an important constituent of the fertilizer mix- tures used in these tests. In fact, when it was omitted from the mix- ture, the cucumber yield was lower than it was from the adjacent check plot and the increase in cabbage yield was so small that the unit cost of the fertilizer was excessive. In the phosphorus series it was the treatment that contained the most phosphorus (4-12-4) and was the most expensive that produced increases in cabbage yields at the lowest cost per unit of crop. With onion sets and sweet corn the unit cost of the increases pro- duced on the plots where phosphorus was omitted was greater than it was from the plots where the 4-4-4 mixture was applied. The most favorable treatment for these crops in the phosphorus series, judged by the cost per unit of crop increase, was the 4-4-4 mixture. 194O] FERTILIZING FOUR VEGETABLE CROPS IN ROTATION 235 Moderate Applications of Potash Sufficient For cucumbers each additional amount of potash in the fertilizer increased slightly the cost per unit of increased yield. For onion sets, however, the greatest cost per unit of increase was with a mixture containing no potash ; consistently good results were obtained with a treatment containing 4 percent of potash. Varying the amount of potash in the fertilizer for sweet corn seemed to have no marked effect on the difference in unit cost of in- creases. Increased cabbage yields cost slightly more when potash was used in the fertilizer than when no potash was used. High Cost of Manure Treatment In Series II, where a comparison was made between the use of a 4-8-4 fertilizer and 20 tons of manure an acre, three of the crops onion sets, sweet corn, and cabbage gave larger increases in yield over the checks when the commercial fertilizer was applied (Table 8). Because of the high cost of the manure, the unit cost of the increases which the manure produced in the yields of each of these four crops was from two to three times as great as the cost of the increases from the commercial fertilizers (Table 9). SUMMARY The scarcity of animal manure, formerly used extensively as a ferti- lizer for market gardens, and recognition that it does not contain in the correct proportions the fertilizing elements needed for garden crops, have led to many studies of substitute materials. Illinois has a special interest in this problem because the production of vegetables for local markets is an important industry in the state. Since onion sets, sweet corn for market, cabbage, and pickle cu- cumbers are four vegetable crops of major importance in the market gardens of northeastern Illinois, a plan was devised for growing them in a four-year rotation. Three cover crops for green manuring were included in each four-year period, and these were supplemented by various combinations of fertilizing materials containing nitrogen, phos- phorus, and potassium. The results of these tests carried on from 1925 thru 1936 at the Cook County Branch Experiment Station, were as follows: 1. Cucumbers gave a very marked response to phosphorus treat- ment, the yields advancing progressively when phosphorus in the ferti- lizer was increased from to 4 to 8 percent. Phosphorus also pro- moted the early development of the crop. 236 BULLETIN No. 464 2. Onion sets responded definitely to nitrogen in commercial form, the highest yield and greatest increase over the adjacent check being obtained from the treatment containing the most nitrogen (6-8-4). Omitting potash from the fertilizer markedly reduced the yield of onion sets. 3. Of the four crops in this experiment, sweet corn was least re- sponsive to the fertilizer treatments used. 4. Cabbage showed very definite response to nitrogen and phos- phorus but not to potash. 5. In the series of plots where cover crops were not grown and where the object was to compare the effectiveness of manure with that of commercial fertilizer, cucumbers produced higher yields ( from ma- nure than from commercial fertilizer, while onion sets, sweet corn and cabbage gave the best results with commercial fertilizer. 6. Costs of increased yields were so high under some treatments as to render the treatments impractical. 7. Economical increases in the yields of cucumbers, onion sets, and cabbage were obtained under certain treatments ; but not one of the treatments here reported caused sufficient increase in the yield of corn to justify its use under the conditions of this experiment. 8. Unit costs of increased yields were much lower when a complete commercial fertilizer (4-8-4) was used than when manure was applied. SUGGESTED TREATMENTS Considering both the increases in yield and the costs of those in- creases, the following fertilizer treatments are suggested for the re- spective crops in this four-year rotation when grown under conditions similar to those in this experiment: 1. For cucumbers an 0-8-4 fertilizer. 1 2. For onion sets a 4-8-4 fertilizer following a cover crop plowed under in the fall. 3. For sweet corn no fertilizer following a cover crop of rye and vetch plowed under in early spring. 4. For late cabbage following a cover crop of sweet clover, a 4-12-4 fertilizer. J An 0-10-5 fertilizer, adjusted as to quantity, would doubtless have given similar results. 8,0503-4018256 UNIVERSITY OF ILLINOIS-URBANA