Soil and leaf nutrient interactions following application of calcium silicate slag to sugarcane
In certain areas of the Everglades Agricultural Area, plant and ratoon sugarcane (Saccharum L.) yields are increased by application of Si from calcium silicate slag. The greatest yield responses are obtained in the plant crop the first year after application of slag and when plant uptake of Si is increased. Magnesium deficiencies have been reported after slag application. The objective of this study was to quantify interactions of soil and leaf nutrients on sugarcane grown on a Terra Ceia muck (Euic, hyperthermic Typic Medisaprist) that had previously received calcium silicate slag. Slag was applied at five rates, and yields were evaluated from plant, first-ratoon, and second-ratoon (stubble) crops at two locations. Soil and leaf from each crop were sampled for nutrient analysis and the results were used to interpret the yield data. Although slag increased cane yield by as much as 39% and sugar yield by 50%, for each 100 mg L–1 drop in extractable soil Mg, cane yields declined by 5.3 Mg ha–1 and sugar yields by 0.9 Mg ha–1. At leaf Si concentrations exceeding 10 g kg–1, optimum cane and sugar yields were observed, while leaf Mg concentrations approached critical leaf concentrations below 1.5 g kg–1. Estimates of total leaf nutrient uptake during each crop indicated that uptake of Mg did not meet nutrient demands at high biomass production. Nutrient antagonism between Si and Mg is suggested. Low soil Mg may contribute to the marked crop responses to slag and for the decline in stubble production. Application of a magnesium fertilizer may be necessary to maintain high nutrient availability.
Available from: Neil Miles
- "lators , and under conditions of favorable Si supply, may absorb more Si than any other mineral nutrient (Snyder, Matichenkov, and Datnoff 2007). There are numerous reports of substantial yield responses following applications of Si to Si-accumulator crops when grown on Si-depleted soils (Fox et al. 1967b;Savant et al. 1999;Berthelson et al. 2003).Anderson (1991)notes that under field conditions, sugarcane requires a leaf concentration of at least 1% Si; at 0.25% Si the yield drops to about one half. Evidence that elevated plant Si levels reduce biotic and abiotic stresses has served to intensify interest in the Si nutrition of crops such as sugarcane. Beneficial effects of Si include improved l"
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ABSTRACT: Reports of sugarcane yield responses to silicon (Si), coupled with mounting evidence that elevated crop Si levels reduce both biotic and abiotic stresses, account for the interest in the Si nutrition of this crop. In terms of managing Si supplies to sugarcane in South Africa, uncertainties exist regarding, first, the reserves of plant-available Si in soils, and second, the reliability of soil-test methods for predicting Si availability. In this study, extractable Si was measured in 112 soils collected from sugarcane-producing fields in South Africa. Soils were selected on the basis of dominant soil types and included Inceptisols, Alfisols, Mollisols, Vertisols, Oxisols, Entisols, and Ultisols, varying widely in chemical properties, texture, and extent of weathering. Extractants employed were 0.01 M calcium chloride (CaCl2) and 0.02 N sulfuric acid (H2SO4). Silicon extracted with 0.02 N H2SO4 ranged from 2 to 293 mg kg−1, whereas with 0.01 M CaCl2 the range was 5 to 123 mg kg−1. With both extractants, extractable Si decreased significantly with decreasing pH, exchangeable calcium (Ca), and total cations. In soils with potassium chloride (KCl)–extractable Al+H levels of greater than 0.5 cmolcL−1, extractable Si levels were consistently low, suggesting that soluble Al is implicated in reducing plant-available Si levels. Extractable Si levels were not related to the Bache and Williams P-sorption indices of soils. In the second part of the investigation, sugarcane leaf Si concentrations from 28 sites were related to soil extractable Si levels. The CaCl2 soil test proved markedly superior to H2SO4 as a predictive test for leaf Si levels.
Available from: Lidiane C. Nunes
- "This value is appropriate for diagnosis of sugar cane leaves taking into account the critical value of 2.5 g kg −1 Si that may limit its productivity  . On the other hand, if one is looking for plant species with lower silicon concentrations, the use of the strongest Si I 288.158 nm emission line (LOD 0.02 g kg −1 Si) is recommended, under the same experimental conditions (i.e. 25 pulses, 50 J cm −2 , 750 μm spot size, 2.0 μs delay time and 4.5 μs integration time gate). "
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ABSTRACT: In spite of the importance of Si for improving the productivity of many important crops, such as those from the Poaceae family (e.g. sugar cane, maize, wheat, rice), its quantitative determination in plants is seldom carried out and restricted to few laboratories in the world. There is a survey of methods in the literature, but most of them are either laborious or difficult to validate in view of the low availability of reference materials with a certified Si mass fraction. The aim of this study is to propose a method for the direct determination of Si in pellets of plant materials by laser-induced breakdown spectroscopy (LIBS). The experimental setup was designed by using a Q-switched Nd:YAG laser at 1064 nm (5 ns, 10 Hz) and the emission signals were collected by lenses into an optical fiber coupled to an Echelle spectrometer equipped with an intensified charge-coupled device. Experiments were carried out with leaves from 24 sugar cane varieties, with mass fractions varying from ca. 2 to 10 g kg− 1 Si. Pellets prepared from cryogenically ground leaves were used as test samples for both method development and validation of the calibration model. Best results were obtained when the test samples were interrogated with laser fluence of 50 J cm− 2 (750 μm spot size) and measurements carried out at Si I 212.412 nm emission line. The results obtained by LIBS were compared with those from inductively coupled plasma optical emission spectrometry after oven-induced alkaline digestion, and no significant differences were observed after applying the Student's t-test at 95% confidence level. The trueness of the proposed LIBS method was also confirmed from the analysis of CRM GBW 07603 (Bush branches and leaves).
Available from: fcav.unesp.br
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