Uptake of Silicon by Sugarcane from Applied Sources May Not Reflect Plant-Available Soil Silicon and Total Silicon Content of Sources

Abstract

Soils of the tropics and sub-tropics are typically acid and depleted of soluble sources of silicon (Si) due to weathering and leaching associated with high rainfall and temperatures. Together with intensive cropping, this leads to marginal or deficient plant Si levels in Si-accumulating crops such as rice and sugarcane. Although such deficiencies can be corrected with exogenous application of Si sources, there is controversy over the effectiveness of sources in relation to their total Si content, and their capacity to raise soil and plant Si concentrations. This study tested the hypothesis that the total Si content and provision of plant-available Si from six sources directly affects subsequent plant Si uptake as reflected in leaf Si concentration. Two trials with potted cane plants were established with the following Si sources as treatments: calcium silicate slag, fused magnesium (thermo) phosphate, volcanic rock dust, magnesium silicate, and granular potassium silicate. Silicon sources were applied at rates intended to achieve equivalent elemental soil Si concentrations; controls were untreated or lime-treated. Analyses were conducted to determine soil and leaf elemental concentrations. Among the sources, calcium silicate produced the highest leaf Si concentrations, yet lower plant-available soil Si concentrations than the thermophosphate. The latter, with slightly higher total Si than the slag, produced substantially greater increases in soil Si than all other products, yet did not significantly raise leaf Si above the controls. All other sources did not significantly increase soil or leaf Si concentrations, despite their high Si content. Hence, the total Si content of sources does not necessarily concur with a product's provision of soluble soil Si and subsequent plant uptake. Furthermore, even where soil pH was raised, plant uptake from thermophosphate was well below expectation, possibly due to its limited liming capacity. The ability of the calcium silicate to provide Si while simultaneously and significantly increasing soil pH, and thereby reducing reaction of Si with exchangeable Al3+, is proposed as a potential explanation for the greater Si uptake into the shoot from this source.

Effects of phytolithic rice-straw biochar, soil buffering capacity and pH on silicon bioavailability

“…The inorganic silicate fertilizer Wo had little significant effect in NI, but the largest one in CA. In the moderately weathered Cambisol CA, Wo addition alleviated mineral toxicities, as it does in other acid soils (Corrales et al 1997;Keeping 2017;Liang et al 2007) and increased plant biomass (Liang et al 2015;Liang et al 1994;Ma et al 2006;Neu et al 2017;Song et al 2014). In contrast, biochar had a marked effect on biomass in NI.…”

Combined Silicon-Phosphorus Fertilization Affects the Biomass and Phytolith Stock of Rice Plants

“…This significant increase was due to the addition of Si fertilizer that can improve the well-observed increase in plant available Si in soils ( Table 2). The DSi release from highly soluble Na 2 SiO 3 , wollastonite and other Si fertilizers (Haynes et al, 2013;Haynes, 2014;Keeping, 2017;Li et al, 2018b;Li et al, 2019) largely contributed to the pool of bioavailable Si, from which it was taken up by plant roots to accumulate around plant transpiration termini. As expected, P fertilizer supply did not change the concentration of available Si in Si 0 level ( Table 2), and thus of phytolith content, regardless of plant part (Table 4).…”

Phytolith‐rich biochar: A potential Si fertilizer in desilicated soils

“…Si fertilization indeed increases crop yields (Berthelsen, Noble, & Garside, 2001;Keller et al, 2012;Liang, Ma, Li, & Feng, 1994;Liang et al, 2015;Meyer & Keeping, 2001;Savant, Snyder, & Datnoff, 1996;Song, Wang, Strong, & Shan, 2014). It is increasingly practiced to improve crop productivity (Datnoff & Heckman, 2014;Datnoff, Snyder, & Korndörfer, 2001;Haynes, 2017;Keeping, 2017;Ma & Takahashi, 2002;Tubana, Babu, & Datnoff, 2016). To date, Si fertilizers consist mainly of silicate slag and natural silicate minerals (Berthelsen et al, 2001;Datnoff & Heckman, 2014;Gascho, 2001;Haynes, 2014;Haynes & Zhou, 2018;Keeping, 2017;Liang et al, 1994;Ma & Takahashi, 2002), as well as nano-Si foliar fertilizers (Puppe & Sommer, 2018).…”

“…It is increasingly practiced to improve crop productivity (Datnoff & Heckman, 2014;Datnoff, Snyder, & Korndörfer, 2001;Haynes, 2017;Keeping, 2017;Ma & Takahashi, 2002;Tubana, Babu, & Datnoff, 2016). To date, Si fertilizers consist mainly of silicate slag and natural silicate minerals (Berthelsen et al, 2001;Datnoff & Heckman, 2014;Gascho, 2001;Haynes, 2014;Haynes & Zhou, 2018;Keeping, 2017;Liang et al, 1994;Ma & Takahashi, 2002), as well as nano-Si foliar fertilizers (Puppe & Sommer, 2018). Although cost-effective because they derive from by-products of furnaces, silicate slags often contain only a small proportion of soluble Si (Haynes, 2014(Haynes, , 2017Liang et al, 2015;Savant et al, 1996), and may present hazardous levels of heavy metals (Belanger, 1995;Haynes, Belyaeva, & Kingston, 2013;Savant et al, 1996).…”