EFFECT OF FERTILIZER PLACEMENTS AND RATES ON

Transcription

1 168 FLORIDA STATE HORTICULTURAL SOCIETY, 1967 EFFECT OF FERTILIZER PLACEMENTS AND RATES ON WATERMELON YIELDS J. G. A. FlSKELL Soils Department, University of Florida Gainesville S. J. Locascio Vegetable Crops Department University of Florida Gainesville P. H. Everett South FloHda Field Laboratory Immokalee H. W. Lundy Suwannee Valley Station Live Oak Abstract Placement of fertilizer just prior to planting watermelons was made as three single bands on one side of the seed bands, on both sides of the seed, a broad band underneath the seed, or broadcast the width of the bed. The fertilizer used was 6-8-8, all mineral, containing either copper or frit 503. The fertilizer rates were 1,000, 2,000, and 4,000 pounds per acre. This was applied in three equal amounts for the nar row, single, and double bands, in a split for the broad band, and in two equal applications for the broadcast treatment. The experiment was conducted at four locations. In general, broadcast fertilization was superior to single and double narrow bands; the latter provided similar yields. Unfavorable response was ob tained to broad band placement at 2^ inches below the seed. This placement caused poor seedling emergence and survival unless planting were followed by rain or irrigation. Also sub sequent growth was delayed so that these melons were later maturing than the other treatments. Plastic mulch encouraged early growth but had little effect on yield. Placements had an effect on soluble salt levels in soil samples taken near the seedlings and in soil near the fertilizer. Rates were also reflected in the soluble salt levels. Nitrogen content of mature leaves at harvest increased linearly with increasing rates and N level in leaves from the broad band was higher than those from narrow bands. Rates Florida Agricultural Stations Journal Series No were reflected in leaf K values. Factors other than rates and placements, possibly soluble salt injury or other effects, accounted for most of the experimental variability. Introduction Fertilization of watermelons in Florida has not been standaradized for several reasons. These include the cost in terms of yield pro duced, cash return on the crop which is highly seasonal, type of equipment available for fer tilizer placement, and grower preference for the method with which he has experience. The trends toward uniformity in size of melons shipped and increased production costs have led to higher fertilizer rates and closer plant spac ing where supplemental irrigation is available. The purpose of the present studies was to pro vide data on the effects on watermelons of vary ing fertilizer rates in several placement patterns. Literature Review The authors have established that Cu fer tilization of flatwood soils, such as Leon and Immokalee fine sands, is of primary importance in yield response of watermelons to fertilizers (4, 8, 9, 10, 11). Correction of soil acidity by liming these soils was also necessary (3). Inter action of Cu and P fertilization was found to affect watermelon yields particularly where diammonium phosphate (DAP) was used (4, 11). Watermelon spacing and fertilizer rates from 500 to 2,000 pounds per acre of were studied by Halsey (6). He placed the fertilizer to one side and slightly below seed level prior to planting. He found close spacing at one ton of fertilizer per acre resulted in smaller but more numerous melons than at lesser fertilizer rates or wider plant spacings. Fertilizer placement studies have been con ducted for a number of vegetables in Florida. Work of Cummings et al. with snap beans was in agreement with several vegetables studied by (1) Nettles (12), and Nettles and Hulbert (13), since single band and double bands of fertilizer were usually adequate when properly placed in the plant bed. However, on unlimed soil, Fiskell and Robertson (5) found that fertilizer mixed throughout the bed after broadcast appli-

2 FISKELL, LOCASCIO, EVERETT, LUNDY: WATERMELONS 169 cation produced much superior potato yields than did banded fertilizer. They noted that in limed soil yield differences were not obtained for broadcast fertilization compared with banded placement. Locascio (7) reported that the mar ketable yield of strawberries under plastic was the same whether the fertilizer was broadcast or banded. According to the DeWit theory of placement of fertilizers (2), at high fertilization rates, broadcast applications of fertilizer might be expected to give higher yields. al Procedure Four experiments were conducted which were generally similar in. character but differed in enough details to warrant their description. Ex periments I, II, and III used all mineral fertilizer. To provide four pounds of copper per acre 0.4, 0.2, or 0.1% Cu as sulfate was mixed with fertilizer to be used at rates of 1,000, 2,000 or 4,000 pounds per acre, respec tively. Four fertilizer placements were tested at the fertilizer rates mentioned. In experiment I on Immokalee fine sand, a single band was placed on the false bed three inches to the side and below the seed site; two more applications at the same rate were applied, one at the thin ning stage and the other at the bed shoulder at layby. This fertilization was termed single band. Another placement, termed double band, was applied similarly except that both sides of the bed were used for the three applications. Another placement, termed broad band, was made by spreading 80% of the fertilizer 10- inches wide on the false bed at a depth of 2Y2 inches below the seed. One-half of the broad cast fertilizer was applied at planting in the bed area and 50% on the remainder of the bed at layby. Three beds each 15-feet long were used per treatment and replicated three times. Plant tissue samples and soil samples were taken at thinning and harvest stages. In experiment II on Leon fine sand, the plant ing bed was opened on both sides and one-third the fertilizer was placed in the single band ap proximately three inches to one side and below the fertilizer for the banded treatments. The second fertilization was made when the beds were reformed at the early growth stage and placement was 12 inches to the other side and at the base of first bed. The third fertilization was banded on the opposite side at layby. The broad band of fertilizer was placed 10-inches wide using 80% of the fertilizer in the center of the bed after the soil was removed to 2Vz inches below the seeding depth used for the bands and then the planting bed was reformed. The remainder of the fertilizer was applied as a band at layby. The broadcast fertilizer was spread over approximately four feet, using 50% of the fertilizer and disced into the soil, after which the bed was reformed. The remaining 50% of the fertilizer was banded 14 inches from the seed at layby. All three rates were done in the same manner. In experiment III on Lakeland fine sand, placement was similar to that in II except that the second application of banded fertilizer was applied two feet from the center of the bed. In experiment IV, the fertilizer con tained frit 503 to supply 45 pounds of this micronutrient source per acre. As before, the fertilizer rates were 1,000, 2,000, and 4,000 pounds per acre. The placement of the single band was alternated from one side to the other for three equal applications. The double bands were also made in three equal applications. The broad band 10-inches wide with 80% of the fertilizer and the bed reformed so that seed placement was 2% inches above the fertilizer; 20% of the fertilizer was applied at either side of the bed at the time the second band applica tion was made. The broadcast treatment re ceived one-half the fertilizer just before plantin and one-half was broadcast at layby on the remainder of the 9-foot plot width. In addition to the regular treatments, fertilization made at the 2,000 pound rate was also covered with plas tic using the above four placement patterns. All the experiments were irrigated and sub jected to normal management for the area. Results and Discussion The watermelon yields from the four experi ments are reported in Table 1. The main fea ture of these data is the reduced yield where the broad band placement of fertilizer was em ployed. The major reason for this effect was the poorer stand and often no seed emergence or seedling mortality that occurred. In this treat ment those plants that survived eventually de veloped fully but fruit set was retarded to such an extent that these melons matured two to three weeks after those in the rest of the ex periment. fertilization was usually superior in melon production to banded fertili zer. Since new land was used in these experi-

3 170 FLORIDA STATE HORTICULTURAL SOCIETY, 1967 Table 1. Effects of fertilizer rate and placemert on yield of Charleston Gray watermelons from four experimentso Fertilizer placement 1 Applications 2 3 % > fert. applied 1000 Fertilizer, lb/a 2000 l a marketable melons tons/a - yield I 80, o ,0 18.U h U I j II III 33o3 8O U * II4..6 ll+.o 6«,U *0 20o IV (plastic) Combined Oii k data U.8 Hi.3 xu a See text for plastic mulch fertilizer placement.

4 FISKELL, LOCASCIO, EVERETT, LUNDY: WATERMELONS 171 ments, the broadcast fertilizer was not observed to increase weed growth seriously over banded fertilizer but this is a factor to consider in use of this placement on old land. It is worthy of note that there was no response to the 4,000 pounds of fertilizer over the 2,000-pound rate which was, however, more effective than the 1,000-pound rate. It was interesting to note also that single band and double band place ments were, with few exceptions, of equivalent efficiency for yield production. This suggested that the watermelon roots were rather tolerant to high soluble salt conditions. However, the decline in yields at the highest rate of broad band fertilization was a result of salt injury which reduced the early stand. Where adequate moisture was present during the early growth such as with experiment I, the young plants survived under this treatment but were reduced to nearly one-half the size of those in other treatments. The broad bands also delayed maturity. This delay in fruit development re sulted in higher yields from these plots at the second and third harvests than for most of the other treatments. The differences in soluble salt levels of soils sampled from each plot and averaged, Table 3, showed both placement and rate effects were present. Since the tolerance of watermelon roots to these soluble salt levels could be judged to some extent by the resultant effect on yields, it must be assumed that injury did exist. This was supported by the fact that the broadcast treatments which had the lowest Table 2. Statistical significance of fertilizer rate and placements on viatermelon yield. Pooled I II III IV Placement 6.8lm* 6.73** 5H5-1O.5CHH5- Rates F values - 6.2$*?:- 7.80** Placement x Rates NoS. ** Significant at the 1% level. For pooled data, broadcast was highest and broad band placement lowest. For experiment I, broadcast was highest over the other three placements and the response was linear to rates. For experiment III, broad cast placement was highest over the other three placements and there was a linear yield decrease with increasing fertilizer rates. For experiment IV, yields of the broad band treatment were highly significantly lower than the two narrow band treatments and less than the broadcast treatment. This also applied for number of marketable melons in this experiment. Single and double bands were alike for production of melons. Total number of fruit was similar for all treatments. soluble salt levels produced the highest yields. Certainly, within these experiments, most of the variability was attributable to some unknown factors other than treatment effects. Since land preparation, liming, cultivation, and disease con trol were uniform in each experiment, soluble salt effects must be suspected to affect water melon growth. This could not be evaluated thoroughly in these experiments because soil moisture levels and rapid root development were uncontrolled variables. The effect of treatments on leaf N and K at harvest is shown in Table 3. Most of the N changes were due to fertilizer rates rather than placement, with the higher broad band treat ments being the exception. The response to rates was linear. Whereas, 2% K or higher K content of young watermelon tissue has been found by the authors, the mature leaves were often much lower than this. Fertilizer place ment showed little effect on leaf K but there was a nearly linear response to rates. Not shown was a very highly significant linear increase in leaf Fe with increasing fertilizer levels. Plastic mulch appeared to encourage lower leaf N and K but this must be considered in light of the earlier plant growth and yields and the fact that the soil was drier under the plastic than in the surrounding overhead irrigated soil. Where seepage irrigation is used, soil remains moist under plastic mulch and this might be a factor useful in study of leaf composition changes during watermelon growth. From these experiments, we conclude that broad band placement under the seed is a hazar dous practice. The reasons are that the young seedlings cannot avoid the fertilizer salt barrier and risk of injury is therefore favored. Single band and double band fertilization when cor rectly placed appear to be equal in effectiveness for melon production. fertilization was best from these few experiments and should be favored where weeds are not a problem. The response to fertilization rates over 1,000 pounds per acre was generally not significant and at this rate there was little evidence that band placement, either broad or narrow, was more effective than broadcast application. LITERATURE CITED 1. Cummings, G. A., A. L. Sharp, J. J. Skinner, G. M. Bahrt, and G. H. Serviss Machine placement of fertilizer for snap beans in Florida. U.S.D.A. Cir DeWit, C. T A physical theory on placement of fertilizers. Versl. Landbouwk. Onderboek. No Everett, P. H., S. J. Locascio, and J. G. A. Fiskell.

5 172 FLORIDA STATE HORTICULTURAL SOCIETY, 1967 Table 3. Effect of fertilizer placement and rate on average soluble salt levels and certain plant properties. Fertilizer placement Fertilizer rates, Ib/A 1,000 2,000 2,000L Soluble salts center of bed 3 months after planting (Exp. I), ppm 1,630 1,530 5,030 1,650 1,930 1,330 5,560 2, Soluble salts remaining in bed after harvest (Exp. I), ppm O ,500 1,330 1, ,200 Soluble salts remaining in initial fertilized area after 63 days (Exp. IV), ppm 1,U80 1,U50 1,560 U50 1,21*0 3,690 1,370 2, ,990 6,370 U,2Uo U,2Uo 1,390 l+,060 1,160 2,060 3, ,800 3,180 2,280 2, ,270 Mature leaf N at harvest (Exp. IV), % k U U.02 U U.UO U.89 3.UU U U U3 Mature leaf K at, harvest (Exp. IV), % U

6 LOCASCIO AND SAXENA: STRAWBERRIES Factors involved in liming soils for watermelon pro duction. Fla. Sta. Hort. Soc. Proc. 78: Everett, P. H., S. J. Locascio, and J. G. A. Fiskell Phosphorus and copper effects on growth and yield of watermelons. Fla. Sta. Hort. Soc. Proc. 79: Fiskell, J. G. A. and W. K. Robertson Com parison of broadcast and row fertilization for potatoes on Kanapaha fine sand. Fla. Sta. Hort. Soc. Proc. 70: Halsey, L. H Watermelon spacing and ferti lization. Fla. Sta. Hort. Soc. Proc. 72: Locascio, S. J Effects of fertilizer placement, organic nitrogen and time of mulching on strawberry yield. Fla. Sta. Hort. Soc. Proc. 77: Locascio, S. J., P. H. Everett, and J. G. A. Fiskell Copper as a factor in watermelon fertilization. Fla. Sta. Hort. Soc. Proc. 77: Locascio, S. J. and J. G. A. Fiskell Copper requirements of watermelons. Amer. Soc. Hort. Sci. Proc. 88 : Locascio, S. J., J. G. A. Fiskell, P. H. Everett, and J. M. Crall Watermelon response to copper and a complete micronutrient source. Fla. Sta. Hort. Soc. Proc. 79: Locascio, S. J., J. G. A. Fiskell, and P. H. Everett. Effect of copper rates and phosphorus sources and rates on watermelons. Amer. Soc. Hort. Sci. Proc. 89: (In press). 12. Nettles, V. F Results from three methods of applying fertilizer to certain vegetables. Amer. Soc. Hort. Sci. Proc. 36: Nettles, V. F. and W. C. Hulburt Effect of placements and levels of fertilizer on the yield of vegetables. Fla. Sta. Hort. Soc. Proc. 79: EFFECTS OF POTASSIUM SOURCE AND RATE AND NITROGEN RATE ON STRAWBERRY TISSUE COMPOSITION AND FRUIT YIELD S. J. Locascio and G. K. Saxena Vegetable Crops Department Institute of Food and Agricultural Sciences University of Florida Gainesville Abstract Strawberries were grown during three sea sons on Ona and Kanapaha fine sands to evalu ate their response to N and K rates and sources of K. Fruit yields were not significantly influ enced by N rates from 46 to 180 lb/acre. In creased rates of K, from 35 to 180 lb/acre had no significant effect on total yield during two seasons. In the third season, a significant reduc tion in total yield occurred as the rate of applied K was increased from 0 to 130 lb/acre. This yield reduction was associated possibly with a K-Mg antagonism. The N and K composition of leaf tissue was increased by increased rates of applied N and K respectively. Sulfate, chloride and nitrate sources of K produced the same leaf tissue composition and total fruit yields. Introduction A number of workers have studied the re sponse of strawberries to N and K rates. Posi tive yield responses to increased rates of N to 100 lb/acre have been reported (8, 12, 14) while Florida Agricultural Stations Journal Series No other workers obtained no yield response (2, 3, 5, 8). In some experiments fertilization with K has also resulted in yield increases (11, 13, 15) but had no effect in others (8, 13, 14). Gener ally, N and K content of the leaf tissue was increased by application of the respective ele ment and yield responses occurred on soils low in available N and K. Most of the above re ported work was done using the matted row system of production or before the introduction of polyethylene as a mulch. s reported here were conducted to evaluate the effect of N and K rates, and three K sources on yield and tissue composition of strawberries. al Procedure Fertility experiments were conducted on Kanapaha fine sands during and and on an Ona fine sand in These soils had been in use for production of other vege tables. From soil test data, the soil ph ranged from 5.8 to 6.1, Ca from 328 to 1,000 lb/acre, Mg from 63 to 95 lb/acre and K from 73 to 89 lb/acre. Treatments were factorial combinations of two or three K sources, three K rates and three N rates. Treatments were arranged in randomized block design and replicated three times. Potassium sources studied were the sul fate, chloride and nitrate. In the sea son, the study did not include the nitrate source. Rates of K and N used are shown in Table 1. The P level applied was a uniform application at the rate of 70 lb/acre from superphosphate.