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Effects of Nitrogen and Potassium Fertilization on Persian Limes on Lakeland Fine Sand
| Content Provider | Semantic Scholar |
|---|---|
| Copyright Year | 2007 |
| Abstract | Mature Persian lime trees on Lakeland fine sand were fertilized for three crop years with three levels each of nitrogen and potassium in factorial combinations. Yields increased with an increase in either nitrogen or potassium up to the maximum levels, with highest yield where both elements were used at maximum levels. Juice content, soluble solids and acid increased with increased nitrogen fertilization. Increased potassium resulted in some increase in acid. Foliage color and denisty improved with increas ing nitrogen fertilization. Calcium and magnes ium levels in leaves decreased as potassium fer tilization increased, but the decrease was not sufficient to cause deficiency symptoms. Introduction While a tremendous amount of research has been devoted to citrus nutrition, little attention has been given Persian (Tahiti) limes in Flor ida. The fertilization of limes has, for the most part, followed practices used for other citrus, as modified by grower trial and error. The major portion of the lime crop is harvested during summer and fall in Florida, but some fruit can be picked every month in the year, as compared Florida Agricultural Experiment Stations Journal Series No. 2810. with a relatively short blooming and harvest season for most orange and grapefruit varie ties. Furthermore, maturity standards for limes are quite different from those for citrus such as oranges and grapefruit. This everbearing habit of limes and their particular maturity standards suggest that more effective fertiliza tion of limes might me developed through sys tematic investigation. Working with limes on Rockdale soil Goldweber et al (1) found that increased nitrogen fertilization increased the number of fruits', total yield, juice, soluble solids and acid, but had no effect on weight of individual fruits. Increasing nitrogen also resulted in increased tree growth and improved leaf color. The effect of phosphorus was inconclusive. Yields de creased where potassium was omitted from the fertilizer. Further studies with limes on Rockdale soil (3) showed that side dressings of potassium nitrate and Uramon increased yields, whereas ammonium sulphate decreased yields. In this investigation, it was found that the natural organic sources of nitrogen were not measurably better for limes than chemical sources. Fertiliza tion at intervals of 60 days was recommend for best results. It was found that limes on Rockdale soil did well on a relatively low but uniform supply of phosphorus (4). Although most of the limes grown, in Florida are produced on Rockdale soil in Dade County, there is significant production of limes on the sandy and loamy soils in warmer sections of the state. No research had been done on lime nutri tion on these sands and loams. An experiment with three rates each of nitrogen and potassium was started in a bearing lime grove near Lake Placid in 1963. This paper reports data ob tained between 1964 and 1967. 338 FLORIDA STATE HORTICULTURAL SOCIETY, 1967 Materials and Methods At the beginning of this experiment in October 1963, the trees were approximately 10 years old. They were on rough lemon root and planted at 20 by 30 feet. The soil was Lakeland fine sand. The soil pH was maintained between 6.0 and 6.7, with extractabe calcium around 600 pounds per acre six inches and magnesium around 75 pounds with annual applications of dolomite. The grove was equipped with solidset, low volume, overhead irrigation. Adequate moisture was maintained, as far as could be determined by tree condition. Although serious cold did not occur in this grove during the period this experiment was in progress, the irrigation system was used a few times for cold protection. There was no cold damage to trees, bloom or fruit. Lime bark disease, with perhaps some blotch, was found throughout the experimental block. Trees used for differential fertilizer treatments in the experiment, however, were as free of the trouble as could be ascertained by normal in spection. There also was some variation in tree size in the experimental area. In laying out the plots, a selective randomization was used so as to have trees of relatively uniform size and vigor among the plots. Three levels each of nitrogen and potash were used in factorial combination, with other fertil izer elements held constant. The four-tree plots were replicated four times in randomized blocks and completely buffered on all sides. The total nitrogen rates for the crop year were 1.5 (Nx), 3.2 (N2) and 4.9 (N3) pounds per tree; potash rates were 1.4 (Kt)f 3.1 (K2) and 4.7 (K3) pounds, with each tree receiving phosphorus and magnesium at 0.34 pound P2O3 and 0.54 pound of MgO. The low rates of nitro gen and potash, together with phosphorus and magnesium, were applied in a mixed fertilizer by distributor over the entire area. The inter mediate and high rates of nitrogen and potash were applied as supplements with ammonium nitrate and muriate of potash spread from tree to tree by hand. These applications were made in fall, winter and spring at rates so as to supply the three levels each of nitrogen and potash in approximately equal amounts each time. The initial experimental fertilization was in October 1963 and the final one in October 1966. Thus, three full crop years, with harvests from mid-spring through late winter, were in cluded well within these treatment limits. Six pickings were made on the plots each year. Yields were obtained for individual plots to the nearest one-tenth of a field box (1.25 bu.). Fruit quality studies were made in 1964, 1965, 1966 and 1967 on fruit samples taken in late spring or early summer. Leaf analyses were made in 1964, 1965 and 1966 on spring-flush leaves collected in early fall. Collections and analytical methods for fruit and leaf samples were essentially those described by Koo, et al (2). A visual rating of general tree condition, based on foliage color and density, was made in December 1966. In rating, chlorosis or sparse foliage obviously caused by lime bark disease or blotch was discounted. Two observations were made on each tree; one on the east side in the morning and one on the west side in the after noon, when light was most favorable from each direction. By late summer of 1966, several trees in the plots were out of production from lime bark disease. Several others were starting to decline noticeably from the trouble. There was no rela tionship between the decline and experimental treatments. Because of increase in rate of the decline, harvest data were not taken after the 1966 crop year, and the experiment was con cluded with collection of fruit samples in May 1967. Results Yield,—Yields for the three years are sum marized in Table 1. There was a definite trend towards increased yield with increased nitrogen and potassium fertilization in 1964 and 1965, but variations among plots under the same treatment were great and the effects were not significant. These variations decreased with time, apparently being reduced by the treatment effects. By the third year (1966) the increase in yield with an increase in nitrogen and potas sium was highly significant. Fruit Quality.—The main effects on fruit quality of the treatments are shown in Table 2. The fruits taken for quality study were all 1% inches or larger in diameter, in accordance with established size standards, and averaged about 2 inches in diameter in all treatments. There was no measurable difference in size among treat ments for the samples taken, as might have YOUNG AND KOO: FERTILIZING LIMES 339 Table 1. Main effect means of nitrogen and potassium fertilization on yield of Persian limes. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://journals.fcla.edu/fshs/article/download/100316/96284 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
