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.
"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). "
[Show abstract][Hide abstract] 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).
Spectrochimica Acta Part B Atomic Spectroscopy 05/2013; s 83–84:61–65. DOI:10.1016/j.sab.2013.02.004 · 3.18 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: region) and disserver the nutrition (Si) and amendment effect of slag when, compared whith lime. The pot trial was carried out in green house at the Ilha Solteira/UNESP, during 1997. Two sucessive harvests were done, variety RB72454, each 210 days after bud emergency. The treatment, besides the control, were constituted by two levels of lime and slag. At the of each cultivation, soil, and leaves were analized, (Ca, Mg, K and P), and the height and cane yield (dry matter) in the aerial part. The sugar cane answered the slag application. The sugar cane answered the slag application. The positive response of slag was mainly due this amendment effect. The slag increased linearly the tillering of sugar cane. INTRODUÇÃO
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