Understanding on the bioavailability of silicon (Si) in intensively cultivated agricultural ecosystem still remains a challenging topic which requires attention by the scientific community. Monosilicic acid (soluble Si) and polysilicic acid (insoluble Si) affect various physicochemical properties of the soil. Thus, quantification of plant available silicon (PAS) content is a crucial step in order to understand the Si-mass balance for a particular region. The main objectives of this study were to quantify the vertical distribution of the PAS content in soils of four different agro-climatic zones of Karnataka and to evaluate the relationship between the physico-chemical properties of soils and PAS content. Four agro-climatic zones of Karnataka namely southern dry zone (SDZ), southern transition zone (STZ), coastal zone (CZ) and central dry zone (CDZ) were chosen for this study. The PAS content extracted by 0.01 M CaCl₂ and 0.5 M CH₃COOH is referred to as dissolved silicon (DSi) and adsorbed silicon (AdSi), respectively. Irrespective of the crop, SDZ and CDZ have medium DSi content (between 20 to 40 mg kg⁻¹) and STZ and CZ have high DSi content (more than 40 mg kg⁻¹). Irrespective of the crop, lowest DSi and AdSi concentration was recorded in SDZ and CZ, respectively. The AdSi content was generally higher than DSi content. On an average, the AdSi content was 2.4 and 4 times higher than DSi in CDZ and SDZ soil profiles of rice, respectively. In case of soil profiles of sugarcane, 2.6 and 4 times higher AdSi content compared to DSi were noticed in CDZ and SDZ, respectively. The depth wise increase in either DSi or AdSi content can be substantiated by the pH effect. Correlation studies indicated that irrespective of the crop, with increase in pH the release of AdSi and DSi content to the solution significantly increased and decreased, respectively. This study also suggested that PAS is essentially released from the finer fractions of soils rather than coarser fractions. Irrespective of the crop, a positive correlation existed between DSi and total organic carbon (TOC) content, whereas TOC correlated negatively with AdSi content. This study suggested that TOC and inorganic carbon (IC) may act as the main and/or potential source of DSi and AdSi content in soil, respectively.

了解集约化农业生态系统中硅 (Si) 的生物利用度仍然是一个需要科学界关注的具有挑战性的话题。单硅酸（可溶性硅）和多硅酸（不溶性硅）影响土壤的各种理化性质。因此，量化植物有效硅 (PAS) 含量是了解特定区域的硅质量平衡的关键步骤。本研究的主要目的是量化卡纳塔克邦四个不同农业气候带土壤中 PAS 含量的垂直分布，并评估土壤理化性质与 PAS 含量之间的关系。卡纳塔克邦的四个农业气候带，即南部干旱区 (SDZ)、南部过渡区 (STZ)、本研究选择了沿海地区 (CZ) 和中部干旱地区 (CDZ)。0.01提取的PAS含量 M CaCl ₂和0.5  M CH ₃ COOH分别称为溶解硅(DSi)和吸附硅(AdSi)。不考虑作物，SDZ 和 CDZ 的 DSi 含量中等（20 到 40 mg kg ^{-1 之间}），STZ 和 CZ 的 DSi 含量高（超过 40 mg kg ^-1）。不考虑作物，分别在 SDZ 和 CZ 记录了最低 DSi 和 AdSi 浓度。AdSi 含量一般高于 DSi 含量。平均而言，在水稻 CDZ 和 SDZ 土壤剖面中，AdSi 含量分别是 DSi 的 2.4 倍和 4 倍。在甘蔗的土壤剖面中，CDZ 和 SDZ 中的 AdSi 含量分别比 DSi 高 2.6 倍和 4 倍。DSi 或 AdSi 含量的深度增加可以通过 pH 值效应来证实。相关性研究表明，无论作物如何，随着 pH 值的增加，AdSi 和 DSi 含量向溶液中的释放量分别显着增加和减少。该研究还表明，PAS 基本上是从土壤的较细部分而不是较粗部分中释放出来的。与作物无关，DSi 与总有机碳 (TOC) 含量呈正相关，而 TOC 与 AdSi 含量呈负相关。该研究表明，TOC 和无机碳 (IC) 可能分别作为土壤中 DSi 和 AdSi 含量的主要和/或潜在来源。