Micronutrients status of Florida soils under citrus production
ABSTRACT Micronutrient nutrition plays an important role in citrus production. Soil extraction techniques to measure the status of bio‐available micronutrients are extremely valuable in the diagnosis of deficient or toxic levels of micronutrients. Mehlich 3 (M3), Mehlich 1 (M1), ammonium bicarbonate‐DTPA (ABDTPA), and ammonium acetate, pH 7.0 (AA), extractants were evaluated for their ability to extract Cu, Fe, Mn, and Zn using 45 citrus grove soils, representing 20 soil series with widely varying physical and chemical characteristics and production practices. The mean concentrations of M3 extractable Fe, Mn, Cu, and Zn were 5.5‐, 2.2‐, 1.6‐, and 1.2‐fold greater, respectively, than those extracted by M1. ABDTPA was more efficient in the extraction of Fe, Cu, and Zn, as compared to the M1 extradant, by 3.3‐, 3.0‐, and 1.4‐fold, respectively. Among the four extractants, AA was extremely inefficient in extraction of all the four micronutrients. Evaluation of the data from all 45 citrus grove soils revealed significant pH effects on extractable Zn by M3, Ml, and ABDTPA extractants and Fe by M1 and ABDTPA extracts only. However, evaluation of the data from pH x Cu experiment on a Candler fine sand (0–15 cm depth soil; pH ranging from 4.5–6.9) showed a negative relationship between the Fe extracted by M3, Ml, and ABDTPA extradants and soil pH. Both extractable Mn and Zn were positively correlated to soil pH except for Mn extractable by ABDTPA. Good correlations (r > 0.52) were observed between M3 vs. Ml extractable Cu, Fe, Mn, and Zn and M3 vs. ABDTPA extractable Cu and Zn. Good correlations were generally found between M3 and AA extractable Cu, Mn, and Zn. However, poor extractability of all micronutrients by AA indicated that it is not a suitable extractant for micronutrient analysis of the soil studied. The results suggest that M3 is a suitable extractant for micronutrient analysis on sandy soils under Florida citrus production.
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HortScience: a publication of the American Society for Horticultural Science 06/2004; 39(3). · 0.86 Impact Factor
- "Therefore, fertilization and irrigation management are critical for commercial citrus production on these soils. Repeated applications of fertilizers or metals-containing pesticides often lead to elevated soil P and trace metals (Alva, 1992; Stanley et al., 1995). Phosphorus and trace metal losses in the surface and subsurface runoff from agriculture to surface waters or groundwater increase with increasing soil P and trace metal levels (Heckrath et al., 1995; Sharpley, 1995; Moore et al., 1998). "
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ABSTRACT: Afforestation in sandy soils can cause soil acidification and affect Cu and Zn release. The behaviors of Cu and Zn release from contaminated arable sandy soils were investigated in the laboratory with the methods of simulated acidification of the soils. The results showed that soil acidification could change chemical forms of Cu and Zn in the soils, impel the transformation of Cu and Zn from carbonate associated fractions to exchangeable, organic matter and oxides associated fractions, and thus increase the release potential of Cu and Zn in the soils. The effect of the acidification on Zn leaching was more significant than that of Cu. Water solubility of Cu and Zn in the soils was increased with decreasing pH, and the solubility of Cu and Zn was increased exponentially at pH 3.8–4.5, and 6.2–6.5, respectively.Journal of Forestry Research 12/2005; 16(4):289-292. DOI:10.1007/BF02858191
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ABSTRACT: Nitrogen (N) fertilizer applied in the NH4+ form results in some degree of soil acidification, which could influence nutrient availability to plants and nutrient losses through leaching. Effects of various N rates (0 – 168 kg N ha-1 yr-1) on soil acidification and nutrient availability were investigated in a Riviera fine sand with 26-year-old white Marsh grapefruit (Citrus paradisi MacFadyen) trees. Soil pH significantly decreased with increasing NH4–N rates. Application of 112 kg N ha-1 yr-1 for four years decreased the pH by 0.7 to 1.7 unit. Soil acidification was greater when the NH4+ form of N fertilizer was applied as dry soluble granular material compared to fertigation or controlled release forms. The marked effect of NH4–N fertilization on the pH of the Riviera fine sand was due to its low buffering capacity. Soil acidification increased the concentration of extractable Fe and P but decreased that of K, Zn and Mn. Soil pH was positively correlated with concentration of Ca, but negatively with concentrations of Fe, Mn and Zn in six-month-old spring flush leaves of the grapefruit trees. Leaf P concentrations, however, were poorly correlated with soil pH. This study also demonstrated an increase in leaching of P and K below the grapefruit trees rootzone with a decrease in soil pH.Plant and Soil 01/1999; 206(1):11-19. DOI:10.1023/A:1004364805789 · 3.24 Impact Factor