Micronutrients status of Florida soils under citrus production
Communications in Soil Science and Plant Analysis (Impact Factor: 0.39). 11/1992; 23(17-20):2493-2510. DOI: 10.1080/00103629209368752
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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- " Some soils in Florida (old citrus groves) contain Cu as high as 4200 mg kg −1 due to fungicide sprays (Mehlich III). A similar pattern was found for Zn and Mn.  Generally, the Vertisols of Iran are mostly developed from limestone and other parent rocks rich in calcium and magnesium, which have high potential for agricultural productions. Although substantial data are documented on properties of Vertisols, few studies are available to assess the effects of long-term continuous cultivation on the level and pattern of trace metals of the soils mainly in calcareous environments. "
ABSTRACT: Dynamics and distribution pattern of trace metals in agricultural lands are an increasing concern due to potential risks to the environment and human health. To ascertain more knowledge of this aspect, the fractions of total and available Fe, Mn, Zn, Cu, and Cd belonging to Vertisols under intensive cultivation and adjoining uncultivated soils were investigated. The order of abundance of metals in both cultivated and uncultivated soils was Fe > Mn > Cu > Zn > Cd and Fe > Mn > Zn > Cu > Cd for both available and total fraction, respectively. A relative enrichment was observed in the value of diethylene-triamine pentaacetic acid-extractable Fe (1.2–201%), Mn (2–31%), Cu (1–40%), and Cd (21–45%) as well as total fraction of Zn (3–17%), Cu (12–32%), and Cd (42–108%) after intensive cropping, which can be contributed to repeated application of agrochemical inputs and manure over long time. The values of RI (potential ecological risk) showed that cultivation caused a low potential ecological risk (33.3% of the soil samples) to moderate potential ecological risk (66.7% of the soil samples) in the study region and that cadmium made up 88%, on average, of the RI value.
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- "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). "
ABSTRACT: To evaluate effects of canopy and micro-irrigation under trees on accumulation and leaching of phosphorus (P) and heavy metals in agricultural sand soils, the horizontal and vertical variations of soil P and metals in a 408-m2 plot within a grove under grapefruit (Citrus paradisi Macf.) production near Fort Pierce, Fla., was examined. A high horizon tal variation of labile soil P and metal concentrations was observed. Across the row, the highest values of pH, EC, water-soluble P, and all metals occurred in the soils under the canopies, and the lowest values occurred in the soils near the water furrow or the midway of the inter-row. Along the grapefruit row, the highest values of many measured variables occurred along the northern side of the citrus tree and close to the emitter. The downward movement of P, Cu, and Zn in the soils was more significant in the soils in open areas (near the water furrow and midway of inter-neighboring trees) than those under the canopies. The differences in labile P and metal spatial distributions in the soils were related to the location of emitter fertigation and differences in rainfall-induced leaching in the field. The results suggest that applying fertilizers to sites under the canopy rather than the spaces between the trees can minimize leaching losses of nutrients.
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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.
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