Dynamics of Silicon in Soil and Plant to Establish Silicate Fertilization

Document Type

Article

Publication Date

1-1-2023

Abstract

Silicon fertilization is an agronomic practice in regions of the world with soils low in plant-available silicon and where high silicon accumulator crops are cultivated. A comprehensive understanding on the dynamics of silicon in soil and plant is fundamental for the development of decision tools for silicon fertilizer recommendation. The most relevant fraction of silicon for plant uptake is the monosilicic acid (H4SiO4), both in liquid (solution) and adsorbed phases. Thus, many of the established soil extraction procedures are formulated to capture this specific form of silicon. Given that the concentration of H4SiO4 in soil is governed by many transformation processes that vary with soil type, climate, and cropping system, the development of standardized procedure for estimating plant-available silicon for agronomic crops remains a long-term research endeavor in soil nutrient management. The absorbed H4SiO4 is immobilized once deposited in leaf epidermal cells and continues to build up with leaf age or as plant grows; therefore, the total plant silicon content can be used to estimate both plant’s silicon removal rate and requirement. The soil and plant silicon content can be used independently for deriving fertilizer recommendations but is not commonly used because of limited established critical silicon levels and interpretations. Also, those currently in use for soil are established using different testing procedures therefore are region-and crop-specific whereas for plant, such information is available for rice and sugarcane only. Currently, silicon fertilizer recommendations are decided based on (a) crop lime requirement, (b) optimal average silicon rate established from numerous studies, and (c) plant shoot silicon removal rate. Rates varies from 2 to 12 Mg ha−1 of calcium silicate, depending on soil initial pH and target pH range. Elemental silicon application rate ranged between 120 to 800 kg ha−1 based on reported optimal rates and 300 to 500 kg ha−1 based on shoot silicon removal rates. All these recommended application rates are mainly for rice (Oryza sativa) with a few for sugarcane (Saccharum spp.). For other field crops like barley (Hordeum vulgare), maize (Zea mays), and wheat (Triticum aestivum), the application rates based on shoot silicon removal rates ranged from 100 to 160 kg silicon ha−1.

Publication Source (Journal or Book title)

Benefits of Silicon in the Nutrition of Plants

First Page

57

Last Page

74

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