Citrus

Citrus fertilization research during the past 80+ years confirm time after time that YaraLiva Calcium Nitrate or CN 9® liquid calcium nitrate is your best choice for increased tree size and productivity, root health, tree longevity and grower profitability. In fact, long term replicated research conducted by the University of Florida on a commercial grove confirmed that calcium nitrate increased pound solids by 12% over ammonium nitrate even at lower rates of nitrogen application.

The University of Florida also published research in 1971 that indicated that in order of importance, nitrogen > potassium > calcium. Tree size and productivity is greatly influenced by these nutrients. So, results confirming the benefits of calcium nitrate over ammonium nitrate, ammonium sulfate or urea should not be surprising. Calcium nitrate fertilizer has 2 of the three most important nutrients for citrus fertilization.

Here is what scientists report about calcium nitrate fertilization of citrus over the years:

"In a Florida experiment, in which plots of 'Valencia' on rough lemon were fertilized with calcium nitrate alone or with ammonium nitrate alone (Tarjan and O'Bannon, 1980), after four years the calcium nitrate treated trees had more foliage, greater vigor, larger diameter and heavier fruit, and more juice." Soil Crop Sci. Soc. Florida Proc. 54:60-65 (1995)

"Fruit production was directly related to tree size. --- Reduction in tree growth was observed when either P, K, Ca or Mg was omitted singly from the fertilizer [N was applied to all treatments]. --- Calcium deficiency was typified by a thin "hard" appearance of the trees. No visible leaf symptoms were found." [Smallest tree size and lowest fruit production was from the minus K treatment. Minus Ca trees, the second lowest in size and production, was slightly better]. Proc. Florida St. Hort. Soc. 84:11-16 (1971)

"The differences in yields were due to adverse soil conditions brought about by certain fertilizers [ammonium sulfate, urea, sodium nitrate] as a result of the accumulation of residues or by cumulative chemical effects. Nitrate of lime [calcium nitrate] apparently had the least effect of this nature. The yields of trees which received this fertilizer have been maintained at a relatively high level throughout the entire experimental period." [Study conducted from 1928-1949] California Ag. Experiment Station Bull. 722, (March 1951)

"The importance of Phytophthora citrophthora and P. parasitica as destroyers of fibrous feeder roots of citrus was demonstrated. Environmental factors favoring the parasitism are excess water and organic matter in the soil. Seedlings fertilized with ammonium sulfate or urea were more susceptible to attacks by these fungi than those receiving calcium nitrate."

Phytopathology 48:616-622 (1958)

" Blight tree root systems exhibit scaffold and fibrous root rot symptoms. These symptoms can be found even on apparently healthy citrus trees Both root rots are caused by the opportunistic fungus Fusarium solani. The fungus was proven to be pathogenic on citrus in 1980 by Nemec." Citrus Industry, p. 31-32 (June 1999)

"It has been reported that ammonium nitrogen can "predispose citrus roots to infection by F. solani. In this study, Fusarium spp. populations were positively correlated with ammonium nitrogen."Soil Crop Sci. Soc. Florida Proc. 56:89-93 (1997)

"Injury from ammonium nitrate used at an acceptable rate of 1.0 kg N/tree in another study (Nemec et al., 1988) caused significantly higher fibrous root rot and lower fibrous root weights compared to the control...The use of ammonium nitrogen may affect F. solani more than the host. Fusarium solani, when grown in culture media where ammonium nitrogen is the sole source of N, produces copious quantities of naphtazarin phytotoxins (Baker et al., 1982) that have been detected in citrus (Nemec et al., 1991) and can cause damage to this crop.

When grown in the presence of N as the nitrate form [calcium nitrate was the nitrate source used in the experiment], no toxins appear to be produced by F. solani (Baker et al., 1982).. This study also demonstrated that populations of Fusaria increase in the soil shortly after use of ammonium nitrate (Table 5) which is coincident with the increase in soil N after fertilization. Increased Fusarium populations may enhance disease potential." Soil Crop Sci. Soc Soc. Florida Proc. 54:60-65 (1995)

Growers should consider planting on deep, well drained soils. Building up the organic matter content of soil would be desirable and may only be possible to a limited extent with cover crops. Fusarium is present in all citrus soils and there are no fungicides available that can eradicate it. Modifying fertilizer rate and form [using calcium nitrate] as described in this article should be considered." Citrus Industry, p. 31-32 (June 1999) 

"The reduced loss of trees associated with 100% calcium nitrate fertilization is consistent with other benefits of this fertilizer form....The calcium in calcium nitrate may provide other benefits that could have accounted for less tree loss in this study. The calcium of calcium nitrate is incorporated as a structural material in calcium-pectate linkages that make plant cell walls more resistant to plant-pathogenic fungus infection (Ko and Kao, 1989). This may be associated with enhanced root mass and health." Soil Crop Sci Soc. Florida Proc. 54:60-65 (1995)

"Of particular interest from a grower's standpoint are the results in the fertilizer plots after only 2 years. Of the 340 trees in each of the nitrogen source treatments, 4.9% or 17 trees, were considered economically unproductive with the calcium nitrate treatment; 6.8% or 23 trees, with the sodium nitrate treatment; and 15.2% or 52 trees, with the ammonium nitrate treatment. Taking this into consideration, the foregoing data seem even more significant." Dr. C. P. Seymour, Chief Plant Pathologist, Florida Department of Agriculture and Consumer Services [Comments on Young Tree Decline], Citrus Industry (May 1976) 

After reviewing these direct quotations from the scientific literature from the past 3 generations of researchers, why would you choose to apply any other nitrogen fertilizer source than YaraLiva™ Calcium Nitrate to your citrus groves? Citrus tree fertilization, productivity, root health, longevity and your profitability is strongly linked. Choose Calcium Nitrate to make that link strong and profitable.